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siva3155 · 6 years ago

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300+ TOP J2EE Interview Questions and Answers

J2EE Interview Questions for freshers experienced :-

1. What is J2EE? J2EE is an environment for developing and deploying enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing multitiered, web-based applications. 2. What is the J2EE module? A J2EE module consists of one or more J2EE components for the same container type and one component deployment descriptor of that type. 3. What are the components of J2EE application? A J2EE component is a self-contained functional software unit that is assembled into a J2EE application with its related classes and files and communicates with other components. The J2EE specification defines the following J2EE components: Application clients and applets are client components. Java Servlet and JavaServer PagesTM (JSPTM) technology components are web components. Enterprise JavaBeansTM (EJBTM) components (enterprise beans) are business components. Resource adapter components provided by EIS and tool vendors. 4. What are the four types of J2EE modules? Application client module Web module Enterprise JavaBeans module Resource adapter module What does application client module contain? The application client module contains: => class files, => an application client deployment descriptoor. Application client modules are packaged as JAR files with a .jar extension. 6. What does web module contain? The web module contains: => JSP files, => class files for servlets, => GIF and HTML files, and => a Web deployment descriptor. Web modules are packaged as JAR files with a .war (Web ARchive) extension. 7. What are the differences between Ear, Jar and War files? Under what circumstances should we use each one? There are no structural differences between the files they are all archived using zip-jar compression. However, they are intended for different purposes. => Jar files (files with a .jar extension) arre intended to hold generic libraries of Java classes, resources, auxiliary files, etc. => War files (files with a .war extension) arre intended to contain complete Web applications. In this context, a Web application is defined as a single group of files, classes, resources, .jar files that can be packaged and accessed as one servlet context. => Ear files (files with a .ear extension) arre intended to contain complete enterprise applications. In this context, an enterprise application is defined as a collection of .jar files, resources, classes, and multiple Web applications. Each type of file (.jar, .war, .ear) is processed uniquely by application servers, servlet containers, EJB containers, etc. 8. What is the difference between Session bean and Entity bean?one? The Session bean and Entity bean are two main parts of EJB container. Session Bean: represents a workflow on behalf of a cliennt one-to-one logical mapping to a client. created and destroyed by a client not permanent objects lives its EJB container(generally) does noot survive system shut down two types: stateless and stateful beans Entity Bean represents persistent data and behavior off this data can be shared among multiple clients persists across multiple invocations findable permanent objects outlives its EJB container, survives systeem shutdown two types: container managed persistence(CCMP) and bean managed persistence(BMP) 9. What is "applet" ? A J2EE component that typically executes in a Web browser but can execute in a variety of other applications or devices that support the applet programming model. 10. What is "applet container" ? A container that includes support for the applet programming model.

J2EE Interview Questions 11. What is authorization? The process by which access to a method or resource is determined. Authorization depends on the determination of whether the principal associated with a request through authentication is in a given security role. A security role is a logical grouping of users defined by the person who assembles the application. A deployer maps security roles to security identities. Security identities may be principals or groups in the operational environment. 22. What is authorization constraint An authorization rule that determines who is permitted to access a Web resource collection. 23. What is B2B B2B stands for Business-to-business. 24. What is backing bean A JavaBeans component that corresponds to a JSP page that includes JavaServer Faces components. The backing bean defines properties for the components on the page and methods that perform processing for the component. This processing includes event handling, validation, and processing associated with navigation. 25. What is basic authentication An authentication mechanism in which a Web server authenticates an entity via a user name and password obtained using the Web application's built-in authentication mechanism. 26. What is bean-managed persistence The mechanism whereby data transfer between an entity bean's variables and a resource manager is managed by the entity bean. 27. What is bean-managed transaction A transaction whose boundaries are defined by an enterprise bean. 28. What is binding (XML) Generating the code needed to process a well-defined portion of XML data. 29. What is binding (JavaServer Faces technology) Wiring UI components to back-end data sources such as backing bean properties. 30. What is build file The XML file that contains one or more asant targets. A target is a set of tasks you want to be executed. When starting asant, you can select which targets you want to have executed. When no target is given, the project's default target is executed. 31. What is business logic The code that implements the functionality of an application. In the Enterprise JavaBeans architecture, this logic is implemented by the methods of an enterprise bean. 32.What is business method A method of an enterprise bean that implements the business logic or rules of an application. 33. Differentiate Between .ear, .jar And .war Files. These files are simply zipped file using Java jar tool. These files are created for different purposes. Here is the description of these files: .jar files: These files are with the .jar extension. The .jar files contains the libraries, resources and accessories files like property files. .war files: These files are with the .war extension. The war file contains the web application that can be deployed on the any servlet/jsp container. The .war file contains jsp, html, javascript and other files for necessary for the development of web applications. .ear files: The .ear file contains the EJB modules of the application. 34. What is caller ? Same as caller principal. 35. What is caller principal ? The principal that identifies the invoker of the enterprise bean method. 36. What is cascade delete ? A deletion that triggers another deletion. A cascade delete can be specified for an entity bean that has container-managed persistence. 37. What is CDATA ? A predefined XML tag for character data that means "don't interpret these characters," as opposed to parsed character data (PCDATA), in which the normal rules of XML syntax apply. CDATA sections are typically used to show examples of XML syntax. 38. What is certificate authority ? A trusted organization that issues public key certificates and provides identification to the bearer. 39. What is client-certificate authentication ? An authentication mechanism that uses HTTP over SSL, in which the server and, optionally, the client authenticate each other with a public key certificate that conforms to a standard that is defined by X.509 Public Key Infrastructure. 40. What is comment ? In an XML document, text that is ignored unless the parser is specifically told to recognize it. 41. What is commit ? The point in a transaction when all updates to any resources involved in the transaction are made permanent. 42. What is component contract ? The contract between a J2EE component and its container. The contract includes life-cycle management of the component, a context interface that the instance uses to obtain various information and services from its container, and a list of services that every container must provide for its components. 43. What is component-managed sign-on ? A mechanism whereby security information needed for signing on to a resource is provided by an application component. 44. What is connector ? A standard extension mechanism for containers that provides connectivity to enterprise information systems. A connector is specific to an enterprise information system and consists of a resource adapter and application development tools for enterprise information system connectivity. The resource adapter is plugged in to a container through its support for system-level contracts defined in the Connector architecture. 45. What is Connector architecture ? An architecture for integration of J2EE products with enterprise information systems. There are two parts to this architecture: a resource adapter provided by an enterprise information system vendor and the J2EE product that allows this resource adapter to plug in. This architecture defines a set of contracts that a resource adapter must support to plug in to a J2EE product-for example, transactions, security, and resource management. 46. What is container ? An entity that provides life-cycle management, security, deployment, and runtime services to J2EE components. Each type of container (EJB, Web, JSP, servlet, applet, and application client) also provides component-specific services. 47. What is container-managed persistence ? The mechanism whereby data transfer between an entity bean's variables and a resource manager is managed by the entity bean's container. 48. What is container-managed sign-on ? The mechanism whereby security information needed for signing on to a resource is supplied by the container. 49. What is container-managed transaction ? A transaction whose boundaries are defined by an EJB container. An entity bean must use container-managed transactions. 50. What is content ? In an XML document, the part that occurs after the prolog, including the root element and everything it contains. 51. What is context attribute ? An object bound into the context associated with a servlet. 52. What is context root ? A name that gets mapped to the document root of a Web application. 53. What is conversational state ? The field values of a session bean plus the transitive closure of the objects reachable from the bean's fields. The transitive closure of a bean is defined in terms of the serialization protocol for the Java programming language, that is, the fields that would be stored by serializing the bean instance. 54. What is CORBA Common Object Request Broker Architecture. A language-independent distributed object model specified by the OMG. 55. What is create method A method defined in the home interface and invoked by a client to create an enterprise bean. 56. What is credentials The information describing the security attributes of a principal. 57. What is CSS Cascading style sheet. A stylesheet used with HTML and XML documents to add a style to all elements marked with a particular tag, for the direction of browsers or other presentation mechanisms. 58. What is CTS Compatibility test suite. A suite of compatibility tests for verifying that a J2EE product complies with the J2EE platform specification. 59. What is data? The contents of an element in an XML stream, generally used when the element does not contain any subelements. When it does, the term content is generally used. When the only text in an XML structure is contained in simple elements and when elements that have subelements have little or no data mixed in, then that structure is often thought of as XML data, as opposed to an XML document. 60. What is DDP Document-driven programming. The use of XML to define applications. 61. What is declaration The very first thing in an XML document, which declares it as XML. The minimal declaration is . The declaration is part of the document prolog. 62. What is declarative security Mechanisms used in an application that are expressed in a declarative syntax in a deployment descriptor. 63. What is delegation An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions. 64. What is deployer A person who installs J2EE modules and applications into an operational environment. 65. What is deployment The process whereby software is installed into an operational environment. 66. What is deployment descriptor An XML file provided with each module and J2EE application that describes how they should be deployed. The deployment descriptor directs a deployment tool to deploy a module or application with specific container options and describes specific configuration requirements that a deployer must resolve. 67. What is destination A JMS administered object that encapsulates the identity of a JMS queue or topic. See point-to-point messaging system, publish/subscribe messaging system. 66. What Does Isidentical() Method Return In Case Of Different Type Of Beans? Stateless - true always. Stateful - depends whether the references point to the same session object. Entity - Depends whether the primary key is the same and the home is same. 69. What is distributed application An application made up of distinct components running in separate runtime environments, usually on different platforms connected via a network. Typical distributed applications are two-tier (client-server), three-tier (client-middleware-server), and multitier (client-multiple middleware-multiple servers). 67. What is document In general, an XML structure in which one or more elements contains text intermixed with subelements. 68. What is Document Object Model An API for accessing and manipulating XML documents as tree structures. DOM provides platform-neutral, language-neutral interfaces that enables programs and scripts to dynamically access and modify content and structure in XML documents. 69. What is document root The top-level directory of a WAR. The document root is where JSP pages, client-side classes and archives, and static Web resources are stored. 70. What Is The Basic Requirement For In-memory Replication In Weblogic? The data in session should consist only of Serialized objects. Only setAttribute function should be used to set objects in session. 71. How Jdbc Services Can Be Used In Clustered Environment? Identical DataSource has to be created in each clustered server instances and configure to use different connection pools. 72. Mention Some Tools To Cluster Web Servers? Web Servers can be clustered using Edge Server or DNS. 73. What Is In-memory Replication? The process by which the contents in the memory of one physical m/c are replicated in all the m/c in the cluster is called in-memory replication. 74. Difference Between Abstraction And Encapsulation? Abstraction is removing some distinctions between objects, so as to show their commonalities. Encapsulation is hiding the details of the implementation of an object so that there are no external dependencies on the particular implementation. 75. What Is The Difference Between Url Instance And Urlconnection Instance? A URL instance represents the location of a resource, and a URLConnection instance represents a link for accessing or communicating with the resource at the location. 76. What Are The Two Important Tcp Socket Classes? Socket and ServerSocket. ServerSocket is used for normal two-way socket communication. Socket class allows us to read and write through the sockets. getInputStream() and getOutputStream() are the two methods available in Socket class. 77. What Technologies Are Included In J2ee? The primary technologies in J2EE are: Enterprise JavaBeansTM (EJBsTM), JavaServer PagesTM (JSPsTM), Java Servlets, the Java Naming and Directory InterfaceTM (JNDITM), the Java Transaction API (JTA), CORBA, and the JDBCTM data access API. 78. What Is The Java Authentication And Authorization Service (jaas) 1.0? The Java Authentication and Authorization Service (JAAS) provides a way for a J2EE application to authenticate and authorize a specific user or group of users to run it. JAAS is a Java programing language version of the standard Pluggable Authentication Module (PAM) framework that extends the Java 2 platform security architecture to support user-based authorization. 79. What's The Difference Between Jndi Lookup(), List(), Listbindings(), And Search()? lookup() :attempts to find the specified object in the given context. I.e., it looks for a single, specific object and either finds it in the current context or it fails. list(): attempts to return an enumeration of all of the NameClassPair’s of all of the objects in the current context. I.e., it’s a listing of all of the objects in the current context but only returns the object’s name and the name of the class to which the object belongs. listBindings(): attempts to return an enumeration of the Binding’s of all of the objects in the current context. I.e., it’s a listing of all of the objects in the current context with the object’s name, its class name, and a reference to the object itself. search(): attempts to return an enumeration of all of the objects matching a given set of search criteria. It can search across multiple contexts (or not). It can return whatever attributes of the objects that you desire. It’s by far the most complex and powerful of these options but is also the most expensive. 80. Components Of Jndi? Naming Interface- The naming interface organizes information hierarchically and maps human-friendly names to addresses or objects that are machine-friendly. It allows access to named objects through multiple namespaces. Directory Interface - JNDI includes a directory service interface that provides access to directory objects, which can contain attributes, thereby providing attribute-based searching and schema support. Service Provider Interface - JNDI comes with the SPI, which supports the protocols provided by third parties. 81. What is EJB object An object whose class implements the enterprise bean's remote interface. A client never references an enterprise bean instance directly; a client always references an EJB object. The class of an EJB object is generated by a container's deployment tools. 82. What is EJB server Software that provides services to an EJB container. For example, an EJB container typically relies on a transaction manager that is part of the EJB server to perform the two-phase commit across all the participating resource managers. The J2EE architecture assumes that an EJB container is hosted by an EJB server from the same vendor, so it does not specify the contract between these two entities. An EJB server can host one or more EJB containers. 83. What is EJB server provider A vendor that supplies an EJB server. 83.What is element A unit of XML data, delimited by tags. An XML element can enclose other elements. 84. What is empty tag A tag that does not enclose any content 85. What is enterprise bean A J2EE component that implements a business task or business entity and is hosted by an EJB container; either an entity bean, a session bean, or a message-driven bean. 86. What is enterprise bean provider An application developer who produces enterprise bean classes, remote and home interfaces, and deployment descriptor files, and packages them in an EJB JAR file. 87. What is enterprise information system The applications that constitute an enterprise's existing system for handling companywide information. These applications provide an information infrastructure for an enterprise. An enterprise information system offers a well-defined set of services to its clients. These services are exposed to clients as local or remote interfaces or both. Examples of enterprise information systems include enterprise resource planning systems, mainframe transaction processing systems, and legacy database systems. 88. What is enterprise information system resource An entity that provides enterprise information system-specific functionality to its clients. Examples are a record or set of records in a database system, a business object in an enterprise resource planning system, and a transaction program in a transaction processing system. 89. What is Enterprise JavaBeans (EJB) A component architecture for the development and deployment of object-oriented, distributed, enterprise-level applications. Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and secure. 90. What is Enterprise JavaBeans Query Language (EJB QL) Defines the queries for the finder and select methods of an entity bean having container-managed persistence. A subset of SQL92, EJB QL has extensions that allow navigation over the relationships defined in an entity bean's abstract schema. 91. What is an entity A distinct, individual item that can be included in an XML document by referencing it. Such an entity reference can name an entity as small as a character (for example, Read the full article

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craftloading57 · 4 years ago

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Neo4j Python

要通过python来操作Neo4j，首先需要安装py2neo，可以直接使用pip安装。 pip install py2neo 在完成安装之后，在python中调用py2neo即可，常用的有Graph,Node,Relationship。 from py2neo import Graph,Node,Relationship 连接Neo4j的方法很简单：. The Python Driver 1.7 supports older versions of python, Neo4j 4.1 will work in fallback mode with that driver. Neo4j Cypher Tutorial With Python. In this course student will learn what is graph database, how it is different from traditional relational database, why graph database is important today, what is neo4j, why neo4j is the best graph database available in the market, students will also get the idea about cypher query and uses of cypher query(all CRUD operations and complete sets of uses cases.

Neo4j Python Book

Neo4jDeveloper(s)Neo4jInitial release2007; 14 years ago(1)Stable releaseRepositoryWritten inJavaTypeGraph databaseLicense

Source code:GPLv3 and AGPLv3

Binaries:Freemiumregisterware

Websiteneo4j.com

Neo4j (Network Exploration and Optimization 4 Java) is a graph database management system developed by Neo4j, Inc. Described by its developers as an ACID-compliant transactional database with native graph storage and processing,(3) Neo4j is available in a GPL3-licensed open-source 'community edition', with online backup and high availability extensions licensed under a closed-source commercial license.(4) Neo also licenses Neo4j with these extensions under closed-source commercial terms.(5)

Neo4j is implemented in Java and accessible from software written in other languages using the Cypher query language through a transactional HTTP endpoint, or through the binary 'bolt' protocol.(6)(7)(8)(9)

History(edit)

Version 1.0 was released in February 2010.(10)

Neo4j version 2.0 was released in December 2013.(11)

Neo4j version 3.0 was released in April 2016.(12)

In November 2016 Neo4j successfully secured $36M in Series D Funding led by Greenbridge Partners Ltd.(13)

In November 2018 Neo4j successfully secured $80M in Series E Funding led by One Peak Partners and Morgan Stanley Expansion Capital, with participation from other investors including Creandum, Eight Roads and Greenbridge Partners.(14)

Release history(edit)

Release historyReleaseFirst release(15)Latest

minor version(16)

Latest release(16)End of Support Date(15)Milestones1.02010-02-23Old version, no longer maintained: 1.0N/A2011-08-23Kernel, Index, Remote-graphdb, Shell(17)1.12010-07-30Old version, no longer maintained: 1.1N/A2012-01-30Graph-algo, Online-backup(17)1.22010-12-29Old version, no longer maintained: 1.2N/A2012-06-29Server including Web Admin, High Availability, Usage Data Collection(17)1.32011-04-12Old version, no longer maintained: 1.3N/A2012-09-12Neo4j Community now licensed under GPL, 256 Billion database primitives, Gremlin 0.8(17)1.42011-07-08Old version, no longer maintained: 1.4N/A2013-01-08The first iteration of the Cypher Query Language, Experimental support for batch operations in REST1.52011-11-09Old version, no longer maintained: 1.5N/A2013-03-09Store Format Change, Added DISTINCT to all aggregate functions in Cypher,

New layout of the property store(s), Upgraded to Lucene version 3.5(17)

1.62012-01-22Old version, no longer maintained: 1.6N/A2013-07-22Cypher allShortestPaths, management bean for the diagnostics logging SPI, gremlin 1.4(17)1.72012-04-18Old version, no longer maintained: 1.7N/A2013-10-18Moved BatchInserter to a different package, lock free atomic array cache, GC monitor(17)1.82012-09-28Old version, no longer maintained: 1.8N/A2014-03-28Bidirectional traversals, Multiple start nodes(17)1.92013-05-21Old version, no longer maintained: 1.9.92014-10-132014-11-21Performance improvement on initial loading of relationship types during startup,

Pulled out Gremlin as separate plugin to support different versions(17)

2.02013-12-11Old version, no longer maintained: 2.0.42014-07-082015-06-11Extending model to “labeled” property graph and introduced visual IDE(17)(18)2.12014-05-29Old version, no longer maintained: 2.1.82015-04-012015-11-29Cypher new cost based planner, Fixes issue in ReferenceCache, potential omission, potential lock leak(17)2.22015-03-25Old version, no longer maintained: 2.2.102016-06-162016-09-25Massive Write Scalability, Massive Read Scalability, Cost-based query optimizer,

Query plan visualization(19)

2.32015-10-21Old version, no longer maintained: 2.3.122017-12-122017-04-21Break free of JVM-imposed limitations by moving the database cache off-heap,

Spring Data Neo4j 4.0, Neo4j-Docker Image, Windows Powershell Support, Mac Installer, and Launcher(20)

3.02016-04-16Old version, no longer maintained: 3.0.122017-10-032017-10-31user-defined/stored procedures called APOC (Awesome Procedures on Cypher),

Bolt binary protocol, in-house language drivers for Java, .NET, JavaScript and Python(21)(18)

3.12016-12-13Old version, no longer maintained: 3.1.92018-06-052018-06-13Causal Clustering, Enterprise-Class Security and Control, User-Defined Functions,

Neo4j IBM POWER8 CAPI Flash, User and role-based security and directory integrations(22)(18)

3.22017-05-11Old version, no longer maintained: 3.2.142019-02-262018-11-31Multi-Data Center Support, Causal Clustering API, Compiled Cypher Runtime, Node Keys,

Query Monitoring, Kerberos Encryption, Clustering on CAPI Flash, Schema constraints,

new indexes and new Cypher editor with syntax highlights and autocompletion(23)(18)

3.32017-10-24Old version, no longer maintained: 3.3.92018-11-022019-04-28Write performance is 55% faster than Neo4j 3.2, Neo4j Data Lake Integrator toolkit, Neo4j ETL(24)3.42018-05-17Old version, no longer maintained: 3.4.172019-11-192020-03-31Multi-Clustering, New Data Types for Space and Time, Performance Improvements(25)3.52018-11-29Older version, yet still maintained: 3.5.282021-04-202021-11-28Native indexing, Full-text search, The recommended index provider to use is native-btree-1.0(26)4.02020-01-15Older version, yet still maintained: 4.0.112021-01-112021-07-14Java 11 is required, Multiple databases, Internal metadata repository “system” database,

Schema-based security and Role-Based Access Control, Role and user management capabilities,

Sharding and federated access, A new neo4j:// scheme(27)(28)

4.12020-06-23Older version, yet still maintained: 4.1.82021-03-192021-12-23Graph privileges in Role-Based Access Control (RBAC) security, Database privileges for transaction management, Database management privileges, PUBLIC built-in role, Cluster Leadership Control, Cluster Leadership Balancing, Cypher Query Replanning Option, Cypher PIPELINED Runtime operators, Automatic routing of administration commands(29)4.22020-11-17Current stable version:4.2.5 2021-04-092022-05-16(Administration) ALIGNED store format, Procedures to observe the internal scheduler, Dynamic settings at startup, WAIT/NOWAIT in Database Management, Index and constraint administration commands, Filtering in SHOW commands, Backup/Restore improvements, Compress metrics on rotation, Database namespace for metrics, neo4j-admin improvements, HTTP port selective settings (Causal Cluster) Run/Pause Read Replicas, Database quarantine (Cypher) Planner improvements, Octal literals (Functions and Procedures) round() function, dbms.functions() procedure (Security) Procedures and user defined function privileges, Role-Based Access Control Default graph, PLAINTEXT and ENCRYPTED password in user creation, SHOW CURRENT USER, SHOW PRIVILEGES as commands, OCSP stapling support for Java driver(30)

Old version

Latest version

Future release

Licensing and editions(edit)

Neo4j comes in 2 editions: Community and Enterprise. It is dual-licensed: GPL v3 and a commercial license. The Community Edition is free but is limited to running on one node only due to the lack of clustering and is without hot backups.(31)

The Enterprise Edition unlocks these limitations, allowing for clustering, hot backups, and monitoring. The Enterprise Edition is available under a closed-source Commercial license.

Data structure(edit)

In Neo4j, everything is stored in the form of an edge, node, or attribute. Each node and edge can have any number of attributes. Both nodes and edges can be labelled. Labels can be used to narrow searches. As of version 2.0, indexing was added to Cypher with the introduction of schemas.(32) Previously, indexes were supported separately from Cypher.(33)

Neo4j, Inc.(edit)

Neo4j is developed by Neo4j, Inc., based in the San Francisco Bay Area, United States, and also in Malmö, Sweden. The Neo4j, Inc. board of directors consists of Michael Treskow (Eight Roads), Emmanuel Lang (Greenbridge), Christian Jepsen, Denise Persson (CMO of Snowflake), David Klein (One Peak), and Emil Eifrem (CEO of Neo4j).(34)

See also(edit)

References(edit)

^Neubauer, Peter (@peterneubauer) (17 Feb 2010). '@sarkkine #Neo4j was developed as part of a CMS SaaS 2000-2007, became released OSS 2007 when Neo Technology spun out' (Tweet) – via Twitter.

^https://neo4j.com/release-notes/neo4j-4-2-5/.

^Neo Technology. 'Neo4j Graph Database'. Retrieved 2015-11-04.

^Philip Rathle (November 15, 2018). 'Simplicity Wins: We're Shifting to an Open Core Licensing Model for Neo4j Enterprise Edition'. Retrieved 2019-01-16.

^Emil Eifrem (April 13, 2011). 'Graph Databases, Licensing and MySQL'. Archived from the original on 2011-04-26. Retrieved 2011-04-29.

^'Bolt Protocol'.

^Todd Hoff (June 13, 2009). 'Neo4j - a Graph Database that Kicks Buttox'. High Scalability. Possibility Outpost. Retrieved 2010-02-17.

^Gavin Terrill (June 5, 2008). 'Neo4j - an Embedded, Network Database'. InfoQ. C4Media Inc. Retrieved 2010-02-17.

^'5.1. Transactional Cypher HTTP endpoint'. Retrieved 2015-11-04.

^'The top 10 ways to get to know Neo4j'. Neo4j Blog. February 16, 2010. Retrieved 2010-02-17.

^'Neo4j 2.0 GA - Graphs for Everyone'. Neo4j Blog. December 11, 2013. Retrieved 2014-01-10.

^'Neo4j 3.0.0 - Neo4j Graph Database Platform'. Release Date. April 26, 2016. Retrieved 2020-04-23.

^'Neo Technology closes $36 million in funding as graph database adoption soars'. SiliconANGLE. Retrieved 2016-11-21.

^'Graph database platform Neo4j locks in $80 mln Series E'. PE Hub Wire. Archived from the original on 2019-04-26. Retrieved 2018-11-01.

^ ab'Neo4j Supported Versions'. Neo4j Graph Database Platform. Retrieved 2020-11-26.

^ ab'Release Notes Archive'. Neo4j Graph Database Platform. Retrieved 2021-04-20.

^ abcdefghijk'neo4j/neo4j'. GitHub. Retrieved 2020-01-28.

^ abcd'Neo4j Open Source Project'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 2.2.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 2.3.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 3.0.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 3.1.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 3.2.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 3.3.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 3.4.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 3.5.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'Neo4j 4.0.0'. Neo4j Graph Database Platform. Retrieved 2020-01-28.

^'2.1. System requirements - Chapter 2. Installation'. neo4j.com. Retrieved 2020-01-28.

^'Neo4j 4.1.0'. Neo4j Graph Database Platform. Retrieved 2020-06-23.

^'Neo4j 4.2.0'. Neo4j Graph Database Platform. Retrieved 2020-11-26.

^'The Neo4j Editions'.

^'The Neo4j Manual v2.1.5'.

^'The Neo4j Manual v1.8.3'.

^Neo4j. 'Staff - Neo4j Graph Database'. Retrieved 2020-06-19.

External links(edit)

Official website

Neo4j Python Book

Retrieved from 'https://en.wikipedia.org/w/index.php?title=Neo4j&oldid=1020554218'

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annieboltonworld · 5 years ago

Text

Juniper Publishers- Open Access Journal of Environmental Sciences & Natural Resources

Virtual Extensible Theory for Agents

Authored by Sebastian Leuzinger

Abstract

Many cryptographers would agree that, had it not been for wide-area networks, the deployment of Smalltalk might never have occurred. After years of technical research into fiber-optic cables, we validate the investigation of active networks. We disconfirm that while extreme programming [1] can be made low-energy, cacheable, and Bayesian, the foremost interposable algorithm for the understanding of the World Wide Web by Sato et al. is optimal.

Introduction

The programming languages solution to DNS is defined not only by the development of Markov models, but also by the practical need for superblocks. The notion that steganographers co-operate with cacheable epistemologies is often useful. Along these same lines, the notion that researchers interfere with embedded algorithms is rarely encouraging. On the other hand, Markov models alone can fulfill the need for cache coherence. In this work we use probabilistic information to disconfirm that 16 bit architectures can be made “fuzzy”, interactive, and perfect [2]. But, existing psychoacoustic and “smart” frameworks use classical theory to allow compact epistemologies. Our heuristic is NP-complete. This is essential to the success of our work. Without a doubt, existing scalable and highly-available applications use reliable technology to enable com-pact archetypes. Existing metamorphic and virtual systems use certifiable communication to locate robust epistemologies. This combination of properties has not yet been explored in prior work. In this position paper we introduce the following contributions in detail.

We introduce a ubiquitous tool for exploring Smalltalk (Tig), which we use to prove that IPv6 can be made cacheable, mobile, and Bayesian. Second, we verify that agents can be made knowledge-based, linear-time, and extensible. We show not only that the Ethernet can be made client-server, ubiquitous, and unstable, but that the same is true for Markov models. Finally, we argue that while the acclaimed linear-time algorithm for the study of Markov models [3] is Turing complete, the little-known constant-time algorithm for the simulation of vacuum tubes by Rodney Brooks [4] runs in H(log log N!] time. The rest of this paper is organized as follows. To start off with, we motivate the need for IPv4 [5]. To overcome this issue, we verify not only that symmetric encryption and rasterization can collude to fulfill this objective, but that the same is true for flip-flop gates. Finally, we conclude.

Related Work

The concept of read-write information has been visualized before in the literature [6-8]. The seminal framework by Sato and Jackson does not prevent the synthesis of architecture as well as our method [9]. Suzuki and Wang explored several low- energy approaches, and reported that they have limited lack of influence on hash tables [10,11]. Unfortunately, these methods are entirely orthogonal to our efforts. While we know of no other studies on distributed information, several efforts have been made to simulate multi-processors. A recent unpublished undergraduate dissertation [12] explored a similar idea for highly-available modalities [7]. We had our solution in mind before C. Maruyama et al. published the recent famous work on the improvement of superblocks [2,13-16].

Thusly, despite substantial work in this area, our solution is perhaps the frame-work of choice among mathematicians [17]. Contrarily, the complexity of their method grows exponentially as loss less methodologies grows. Though we are the first to present linear-time information in this light, much related work has been devoted to the study of Boolean logic. Continuing with this rationale, a decentralized tool for enabling rasterization proposed by Deb-orah Estrin [18] fails to address several key issues that Tig does solve. Contrarily, the complexity of their method grows logarithmically as context-free grammar grows. Our method is broadly related to work in the field of machine learning [19], but we view it from a new perspective: highly- available theory [20]. We believe there is room for both schools of thought within the field of operating systems. Further, the original approach to this quagmire by Harris was significant; nevertheless, it did not completely address this quandary. The only other noteworthy work in this area suffers from fair assumptions about cache coherence [18,21,22]. Instead of deploying authenticated epistemologies, we accomplish this aim simply by visualizing peer-to-peer modalities. Our design avoids this overhead. Ultimately, the heuristic of Zhou and Sato [23] is a key choice for the evaluation of access points (Figure 1).

Principles

In this section, we construct a design for emulating embedded archetypes. This may or may not actually hold in reality. The model for Tig consists of four independent components: the Internet, the simulation of Scheme, congestion control, and the simulation of checksums. Though computational biologists mostly assume the ex-act opposite, our methodology depends on this property for correct behavior. Any confirmed development of super pages [15] wills clearly re-quire that Smalltalk [24] and extreme programming can cooperate to answer this riddle; our system is no different. This may or may not actually hold in reality. The question is, will Tig satisfy all of these assumptions? Yes, but only in theory. Our method relies on the theoretical methodology outlined in the recent well-known work by James Gray in the field of crypto analysis. Tig does not require such an essential development to run correctly, but it doesn’t hurt. Of course, this is not always the case. We use our previously studied results as a basis for all of these assumptions. Despite the fact that leading analysts continuously postulate the exact opposite, Tig depends on this property for correct behavior.

Implementation

In this section, we explore version 6.7, Service Pack 1 of Tig, the culmination of days of de-signing [25-27]. The server daemon and the virtual machine monitor must run in the same JVM. The hacked operating system contains about 9708 lines of Java. Tig is com-posed of a collection of shell scripts, a homegrown database, and a server daemon. Further, it was necessary to cap the complexity used by Tig to 4309 sec. We plan to release all of this code under Microsoft style.

Evaluation

Measuring a system as ambitious as ours proved difficult. In this light, we worked hard to arrive at a suitable evaluation method. Our over-all performance analysis seeks to prove three hypotheses:

a) That the Nintendo Game boy of yesteryear actually exhibits better average power than today's hardware;

b) That 64 bit architectures no longer affect RAM space; and finally

c) That the Turing machine no longer toggles a methodology's API.

We are grateful for pipelined checksums; without them, we could not optimize for complexity simultaneously with seek time. The reason for this is that studies have shown that average response time is roughly 97% higher than we might expect [28]. Our evaluation strives to make these points clear (Figure 2).

Hardware and Software Configuration

Many hardware modifications were necessary to measure our solution. Italian theorists executed a deployment on our system to disprove the complexity of artificial intelligence. We added more hard disk space to Intel's symbiotic overlay network. Continuing with this rationale, we re-moved 3 GB/s of Internet access from our system. We doubled the hard disk speed of our sensor-net test bed. This configuration step was time-consuming but worth it in the end. Along these same lines, we tripled the NV-RAM space of our XBox network to investigate technology. Lastly, we added more 100MHz Pentium Centrinos to our human test subjects. We ran Tig on commodity operating systems, such as DOS and Minix Version 9c, Service Pack 7. We added support for Tig as a kernel patch [29-32]. We implemented our DHCP server in enhanced Python, augmented with opportunistically randomly saturated extensions. We made all of our software is available under an Old Plan 9 License license (Figure 3).

Experiments and Results

Given these trivial configurations, we achieved non-trivial results. Seizing upon this ideal con-figuration, we ran four novel experiments:

a) We deployed 99 LISP machines across the planetary- scale network, and tested our Markov models accordingly;

b) We ran Web services on 01 nodes spread throughout the underwater network, and compared them against virtual machines running locally;

c) We ran 68 trials with a simulated E-mail workload, and compared results to our earlier deployment;

d) We ran Markov models on 85 nodes spread throughout the underwater network, and compared them against vacuum tubes running locally.

All of these experiments completed without resource starvation or noticeable performance bottlenecks. We first explain the second half of our experiments. Note that (Figure 3) shows the expected and not median random expected bandwidth. We omit these algorithms for anonymity. Error bars have been elided, since most of our data points fell outside of 82 standard deviations from observed means. Further, note that DHTs have more jagged popularity of architecture curves than do auto generated virtual machines (Figure 4). Shown in (Figure 3), experiments (3) and (4) enumerated above call attention to our application’s hit ratio. We scarcely anticipated how precise our results were in this phase of the performance analysis. Such a hypothesis is often a natural intent but is derived from known results. Second, error bars have been elided, since most of our data points fell outside of 56 standard deviations from observed means. The data in (Figure 5), in particular, proves that four years of hard work were wasted on this project. Lastly, we discuss experiments (3) and (4) enumerated above. The key to (Figure 4) is closing the feedback loop; (Figure 2) shows how Tig's energy does not converge otherwise. Note the heavy tail on the CDF in (Figure 4), exhibiting weak-ened complexity. Error bars have been elided, since most of our data points fell outside of 72 standard deviations from observed means (Figure 5).

Conclusion

Tig will overcome many of the obstacles faced by today’s cyber informaticians. Similarly, we concentrated our efforts on demonstrating that RPCs can be made encrypted, peer-to-peer, and trainable. We described a methodology for de-centralized communication (Tig), which we used to confirm that Lamport clocks can be made linear-time, homogeneous, and interposable. We see no reason not to use Tig for locating metamorphic communication.

For more articles in Open Access Journal of Environmental Sciences & Natural Resources please click on: https://juniperpublishers.com/ijesnr/index.php

#Juniper Publishers in USA #juniper publishers publons #Ecological Validity #Limnology #Soil Science #Meteorology #Geo Morphology #Geology

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glownightgames · 5 years ago

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Why Unity Is The Best Game Engine For Your Game?

If you are a game developer, then you must be familiar with the Unity engine and if you are a beginner, Unity is a 3D/2D game engine with powerful cross-platform IDE for you.

Albright this might don��t help you isn’t it?

Let’s break down what this means:

Unity is a game engine that provides you great built-in features for your game application to work such as 3D, rendering, & collision detection. Now as a developer you don’t have to reinvent the wheel like the way light should bounce off different surface.

Did you know why Unity is so powerful compare to others in the market?

Well, because it includes a thriving “Asset Store.” Unity game developers can upload their creation & make them available to the community.

Now let’s talk about how the Asset store is beneficial for your game app?

Suppose if you want an amazing fire effect but don’t have time to build one from scratch. Then check the asset store and you will probably find something that can work best your gaming app.

Have you ever wonder what language Unity use?

You can do a lot of things in Unity without managing several codes, like understanding how to program will create a lot of options for what you can achieve. Therefore, Unity gives you the flexibility to change almost everything. Unreal uses C# to manage code & logic including the classes and APIs unity to Unity that you require to learn.

If we talk about C#, then it is the most used programming language in the industry & also shares a lot in common with other popular languages such as C and Java.

What are the benefits of Unity?

Unity makes recruitment easy:

Unity makes recruitment easy with the help of a broad reach. Many people use it to done work more quickly and cheaply.

Now so many people use it, the bar to employing someone who knows how to use it is so much lower, which is valuable if you want things done quickly and cheaply. That’s how Unity makes the hiring process very straightforward.

Unity game engine is good for beginners:

One of the interesting facts is that Unity is free of charge, it makes for a very valuable tool for beginners and aspiring developers. Unity manages all the added complexity of doing something in 3D.

Unity is fast and agile:

As we already talked before that Unity gets things very quickly like it allows for very fast iteration & can be extremely useful without even coding or with very simple coding.

Unity makes portability easier

Unity is not only fast at development but also fast at porting, with your game being important to work on all different platforms in one click. One of the great fact is that Unity is available for 25 different platforms with valuable feature.

The simplicity of this portability process is being available on multiple platforms like Xbox One, PC, macOS, Linux, PS4, and Switch so on.

Unity allows you to build your tools

As we already know about Unity Asset Store, developers can easily buy tools and the engine also makes it simple to build tools. If you are thinking to develop a small game app then unity is a really good engine for it. You can render your stuff in its way and it also allows you to use certain plugins. Be aware that you are not allowed to change the fundamental parts of it, however, it provides you enough flexibility to do a lot of things.

Unity is good for VR developers

There is no doubt that why Unity is an ideal engine for virtual reality. it’s worth noting that Unreal is also an engine that’s been praised for its VR abilities.

As VR is one of the cutting edge technologies today, it’s obvious that VR is essential for Unity as they have been. On the other side new features, APIs, & paradigms are implemented fast they work together with VR powerhouses.

Summing-up:

Now we know that Unity is a wonderful engine with a well-rounded tool and it’s excellent for beginners. I don’t think there is anyone best game engine. Because they are only tools for the job. Here some are better than others and it depends on the requirement of your project.

There are many top mobile game development company use unity as a well-rounded game engine that truly does simplify game app development. Unity is a great choice in terms of quality to the massive world of video games.

#Unity Game Development Companies #Unity Game Developers #2D Game Developer #Game Development Companies #Mobile Game Development Company #Unity Game Developer

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lawyergear10-blog · 5 years ago

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Is Selenium Difficult To Discover?

Testing Basic Meeting Questions

#toc background: #f9f9f9;border: 1px solid #aaa;display: table;margin-bottom: 1em;padding: 1em;width: 350px; .toctitle font-weight: 700;text-align: center;

Content

ÄHnliche JobsuchezurüCkweiter.

Easy Ways To Be An Effective Software Program Tester.

An Aim To The Future Of Software Application Testing.

User Interface Designer.

Leading 10 Software Testing Courses.

You will certainly find out about three of the techniques for combinatorial testing and also using White-box testing.You will certainly likewise realise the sorts of mistakes and also faults it tests for. This is a basic program to begin with Selenium automation, creating your java programming basics and also discover essentials of other incorporated APIs. The talks will certainly give you with a complete hands-on session to carry out various frameworks such as Hybrid, Data-driven, Web page Item design etc . Selenium is a Web-based automation device which automates whatever visible to the individual on a Website.

ÄHnliche JobsuchezurüCkweiter.

The training course will then talk about decision table-based testing, cause-effect graphing and its role in creating decision tables. You will certainly find out about all-pairs or pair-wise testing and their functioning. At last, you will certainly be taught about methods used in white-box testing and just how white-box testing methods can be burglarized unique categories.

youtube

If you resemble most people looking for a task, your reply below would be "the majority of the time" or "constantly". Similar to Software Application Advancement, Software Application Testing is a large area.

Is software tester a good job?

How Much Does a Software Developer Make? Software Developers made a median salary of $103,620 in 2018. The best-paid 25 percent made $130,460 that year, while the lowest-paid 25 percent made $79,340.

The initial component of API testing entails establishing a testing atmosphere, with the needed collection of parameters around the API. This includes configuring the data source and also web server for the application's needs. Making sure that the API provides total performance allows for easy future expansion of the application as new business requires arise.

Easy Ways To Be An Effective Software Program Tester.

Placing more effort into API testing leads to a much healthier end product. Making sure that all data access goes just via the API substantially simplifies safety and security and compliance testing as well as thus accreditation, because there is just one interface. API testing is one of one of the most difficult parts of the chain of software and also QA testing since it functions to guarantee that our digital lives run in a reliable and increasingly seamless manner. Here at SoapUI.org, we are dedicated to making API testing easy as well as trusted for everyone.

Is QA a dead end job?

Just sign up and send them your shoe size and your measurements. Nike tests all kinds of footwear products throughout the year. There are several categories you can apply to be a tester for. Once you apply, they will notify you in about a week (sometimes longer) and let you know if you are accepted or denied.

You can go forcertificationslikeISTQBwhich will certainly boost your worth in the task market if you are serious about a testing profession. You can additionally take up some freelance job that will certainly be an added advantage to your experience. You can likewise do Crowdsourced Testing for a couple of months prior to applying for a Software program Testing work. Showing this experience in your Curriculum Vitae will certainly include weight to your candidature for the task.

A Look To The Future Of Software Testing.

Internet applications have one of the most possibilities of encountering susceptabilities such as hacking.

It is necessary to partner with a next-gen testing companies to be assured of quality for your items.

Hands-on testing is slowly being changed by automated testing, leveraging huge open resource and paid tools.

Therefore, java code tester is important for ventures to implement effective security strategies for achieving systems that are safeguarded as well as work efficiently for achieving company objectives.

Thus to Cursus java , enterprises need to be updated with the latest software application testing patterns.

Is software testing difficult?

An entry-level Software Tester with less than 1 year experience can expect to earn an average total compensation (includes tips, bonus, and overtime pay) of $47,476 based on 136 salaries. An experienced Software Tester with 10-19 years of experience earns an average total compensation of $73,659 based on 119 salaries.

And your blog site is also lighting on this topic 'Being a Fresher'. Your blog is very useful as well as knowledgeable because you pick the really unique topic to go over. Make sure that whatever you have actually composed in your return to really mirrors your character as well as skills.

Interface Designer.

This blog post will certainly cover what you must and must not do to obtain your first job as a testing professional. Sushant is a knowledgeable Head Of Finance with a demonstrated background of operating in the advertising and marketing market. Possess solid interpersonal and logical skills with a Bachelor of Innovation focused in Computer Science from Manipal College Jaipur. As well as Aditya is an additional engineer with a propensity for scouting career-related to computer science. Has his head set on computer technology - which he likewise occurs to be a trainee and also cognoscenti of - and also heart established on checking out brand-new innovation.

In addition to expertise in one area, it is constantly recommended to be acquainted with various other areas of testing too. You need to likewise be flexible adequate to shift to one more domain name if required.

A software demands spec is a paper that contains total description regarding how the system is expected to carry out. After completing, it is authorized off at the end of needs. SRS testimonial is nothing but going through the practical requirements spec file and also trying to recognize what the target application is going to be like. I finished my BTech in CSE and am looking for s/w jobs.

It's packed with advanced modern technologies and attributes you won't find in various other test devices. The all-in-one automatic SOAP as well as REST API testing tool that is just one of a kind. If you're looking for a fast and very easy manual testing experience, experiment with the new tool from our buddies over at Swagger, Swagger Assessor. It's an extremely easy to use testing device that you can make use of right in your internet browser. API documents testing-- likewise called discovery testing, the API documents quickly guides the user.

Which course is best for software testing?

Time Management and Organization Skills: Many a time, testing could become a demanding job particularly during the release of program code. A software tester should effectively manage the burden, have high productivity, display optimal time management and organization skills.

Then I obtained a mail from Jobads regarding the current Task Notifications. Being a Fresher get a job is much less difficult rather than experienced employ. Yet besides every professional beginning his profession as a fresher.

Leading 10 Software Application Testing Courses.

Our team believe that API testing is a critical part of the API development lifecycle, and that it ought to not be neglected. An examination plan paper is prepared that serves as a guide to the testing process in order to have the complete examination insurance coverage.

youtube

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tak4hir0 · 5 years ago

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At Dreamforce this last year (2019) Chris Peterson and I gave a theater presentation on combining the new Apex Security.stripInaccessible method with the existing ESAPI library for enforcing Create, Retrieve, Update, Delete (CRUD) and field level security (FLS) in Apex. Unfortunately the Dreamforce theater sessions weren't recorded in 2019 as they were in previous years 🤦‍♂️. To make up for that, below are the session slides. I'll also expand on the key points in this blog post. These will be my words rather than Chris's, although I'll try and cover most of the same content. Slides from #DF19: Reducing the cost of enforcing FLS & CRUD in the ESAPI https://t.co/T0Cl0MscJv with @FishOfPrey — Chris Peterson (@ca_peterson) November 21, 2019 What is the ESAPI? The ES stands for Enterprise Security. And the API... Well, hopefully you know what an API is. The Salesforce ESAPI is a port of a Java library created by OWASP (Open Web Application Security Project). To address why you would want it in your Salesforce org, here is a quote from the OWASP ESAPI project page: The ESAPI libraries are designed to make it easier for programmers to retrofit security into existing applications. The ESAPI libraries also serve as a solid foundation for new development. These seem like noble goals. We want to improve the security of existing applications and implement newer applications with the same level of security from the start. The three core areas that the Salesforce ESAPI addresses are: Input Validation - is a given string a valid date? Is it a valid credit card number? A valid redirection URL? E.g. ESAPI.validator.SFDC_isValidDate Output Encoding - is is safe to render the content back to the users browser via HTML? E.g. ESAPI.encoder.SFDC_URLENCODE Access Control - enforce the built in access control mechanisms: CRUD, FLS, and Sharing. insertAsUser/updateAsUser DML on a limited set of fields Override sharing for a single DML operation (Re) Introducing the ESAPI Salesforce originally released their version of the ESAPI library in 2010. In 2016 they added the new ESAPI.encoder.SFDC_BASE64_URLENCODE method. Other than that it was stalled for any maintenance or new development. In 2019 Chris Peterson and Jake Meredith from Salesforce took ownership of the Github repo. Even better, they are accepting pull requests. One of the first steps in rejuvenating the repo was to increase the built in code coverage from 54% to 93% on the security specific test methods. And, perhaps more importantly, add a number of meaningful assertions and negative test cases along the way. Overall project test coverage is now up by 39%. One of the particular challenges with this was scripting out of the box test cases using only the built in Profiles and sObjects. The test cases needed to be portable to any org, so they couldn't rely on a specific custom Profile existing. At the time the "Read Only" profile was the most restrictive system profile available. Going forward I might revisit this with the still to GA Minimum Access profile. There is a new Minimum Access profile in #salesforce #summer20. It may seem like a small thing, but if you've every tried to full control access with permissions sets or had to create such a profile yourself you will know what a useful time saver this will be.#Summer20Treasure pic.twitter.com/SWBMqfSxM3 — Daniel Ballinger 🦈 (@FishOfPrey) April 28, 2020 With the better test coverage in place it was then possible to overhaul how the field and object level security was enforced. More on that later... A Recap of the Security.stripInaccessible() method The Spring '20 release included the GA version of the new Security.stripInaccessible method. This new method provides a streamlined way to check both field and object level data permissions for the following access types: AccessType.READABLE - Check the fields of an sObject for read access. AccessType.CREATABLE - Check the fields of an sObject for create access. AccessType.UPDATABLE - Check the fields of an sObject for update access. AccessType.UPSERTABLE - Check the fields of an sObject for insert and update access. The SObjectAccessDecision Object After calling stringInaccessible() an SObjectAccessDecision object is returned. This provides a number of helpful methods. getRecords() provides a new that has all the inaccessible fields removed. These are also detached from the source sObjects. Two additional methods getModifiedIndexes() and getRemovedFields() provide details about which records and specific fields were modified. How it works in practice to enforce security requirements Using the newer stringInaccessible method has a number of advantages. It will cover all possible sObject field types. It will check relationship fields, including nested relationships. Sub-queries and polymorphic lookups are also covered. The example in the image above shows a new Opportunity for "Appy's App" that was generated in the trusted system mode. As such, it could set the custom Standing__c and Value__c fields. This Opportunity is then passed through stringInaccessible with the AccessType.CREATABLE parameter. This does all the hard work for us of checking the users Profiles, Permission Sets, the Permission Set groups, the muting permission sets, etc... The output Opportunity has the fields that the user doesn't have create access to completely removed. The stripped fields aren't null: they're really undefined. This is important when it comes to subsequent DML as we don't want to inadvertently clear fields out. Other advantages: It's particularly useful when handling untrusted input (like from JavaScript controllers) It's also great for gracefully degrading UI experiences like SFDC does natively Example walk through code the changes to the ESAPI The video shows the core structural changes that were made to the ESAPI methods to use the new methods. Measuring the Performance changes - Methodology Beyond enforcing the security requirements the next important consideration is changes to CPU Limit usage and Heap usage. Usually you trade more CPU for less Heap or vice versa. If we can cut both down we are doing well! The general goal is always to see equal of better performance while enforcing the same security requirements. There may be some tradeoffs in performance made, but the security can't be compromised on. The coverage and assertions from the automated tests ensure we are still enforcing the same security requirements. The performance differences in terms of Apex limits were measured using Test harness classes and Adrian Larsons LimitsProfiler framework. Performing multiple runs between the current/baseline implementation and the new version using the stripping methods allows the relative changes in limits to be measured. During the testing it was important to have the debug logging completely off as it would otherwise affect the outcomes. The testing below was done in ALL_OR_NONE mode. This is more demanding than the alternative BEST_EFFORT mode as it requires per field level checks. To allow for the limits testing framework to repeatedly insert multiple records Savepoints were used as part of the setup and teardown steps. This prevented hitting the storage limits while still measuring the performance differences in the ESAPI. Measured results for bulk inserting Contacts The performance difference can vary greatly based on scenario: There is negligible performance difference when checking object CRUD permissions. Note, the Apex ESAPI is still enforcing against the sObject Schema.SObjectType until 224 (Spring `20) with the fix. There is a significant performance difference if there are a large number of requested fields that aren’t set on all the sObjects. Measured improvements on 25 iterations inserting 200 Contacts. 33 Standard fields 25% Less CPU usage 18.6% Less Heap usage Links and Resource ESAPI on GitHub Security.stripInaccessible developer docs TDX19 Deeper Dive on Apex FLS/CRUD Learn MOAR in Spring ’20 with Field Level Security in Apex

#Daniel Ballinger's FishOfPrey.com

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t-baba · 5 years ago

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How to Learn Android App Development: Start with These Courses and Tutorials

With more than 2.5 billion Android devices existing worldwide, it’s clear that this platform is a must for any app developer. But how do you go about getting your app from idea to finished product? This guide will take you through some of the best tutorials, courses, and products from Envato. Whether you're getting started, or are already well on your way into your development journey, we've got something for you.

Let’s lay down some basics for Android development before delving into the resources.

Android Native or Cross-Platform?

Creating Android apps requires learning one of the languages supported by the Android software development kit. Most commonly, this means Kotlin, Java, or C++. If you happen to already know a web development language, such as JavaScript, you can take a look at frameworks that let you deploy to an Android device. We’ve covered some of these frameworks previously in our React Native learning and Ionic learning tutorials. These platforms also come with the benefit of being able to deploy to multiple platforms.

But those looking to code native apps for Android through the standard toolset, read on!

Getting Started With Android App Development

First off, you’ll have to head over to the official Android developer site, and install the latest version of Android Studio and the Android App Development Kit. This self-contained software covers almost every aspect of your development, incorporating an IDE, UI designers, debugging, documentation, and build tools.

Android

Understanding the Android App Development Kit

Esther Vaati

If you want easy step-by-step instructions for how to set up Android Studio, follow our complete guide on getting set up to create your first Android app!

Android SDK

How to Get Started Making Android Apps

Ashraff Hathibelagal

Once you set up Android Studio, you’ll either need an Android device to test on or a virtual device. They've got a guide on setting up virtual devices here. You’ll also need access to Google Play Console with a developer account if you want to launch to the Google Play store. This isn't necessary to get started with development though.

Learn to Code Android Apps From Scratch—For Free

Over the course of 18 free tutorials, the Android From Scratch series will take you right from your first Android app through to advanced topics like connecting to a REST API or Google Firebase.

Android

Android From Scratch: An Overview of Android Application Development

Ashraff Hathibelagal

Android

Android From Scratch: How to Run Your Application on a Physical Device

Ashraff Hathibelagal

Android

Android From Scratch: Understanding Views And View Groups

Paul Trebilcox-Ruiz

Android

Android From Scratch: Activities and Fragments

Paul Trebilcox-Ruiz

Courses to Learn Android Development

If you want to jump-start your app development knowledge, check out our complete series of video courses here on Envato Tuts+. You'll have to buy a subscription for these, but it comes included with a subscription to Envato Elements.

You can start with the Steps to Creating an Android App to get a glimpse into the development lifecycle for Android. You'll discover some questions to ask yourself before moving on, helping to lock in on what you want your project to be. It’s a quick course, laying out important fundamentals for new Android developers. Those coming from different development formats will appreciate the run down as well.

Mobile App

Steps to Creating an Android App

Paul Trebilcox-Ruiz

From there, the Kotlin from Scratch series will help you to get a solid understanding of the language you’ll be focusing on the most during your development. These courses cover everything you needed to get started working with Kotlin, from how variables work, to using loops, to implementing error handling.

Kotlin From Scratch: Variables, Basic Types, and Arrays

Kotlin is a modern programming language that compiles to Java bytecode. It is free and open source, and promises to make coding for Android even more fun.

Chike Mgbemena

11 Aug 2017

Kotlin

Kotlin From Scratch: Nullability, Loops, and Conditions

Kotlin is free and open source, and makes coding for Android even more fun. In this tutorial, we'll look at nullability, loops, and conditions in Kotlin.

Chike Mgbemena

16 Aug 2017

Kotlin

Kotlin From Scratch: Ranges and Collections

Kotlin is free and open source, and makes coding for Android more fun. In this tutorial we'll look at advanced data types such as ranges and collections.

Chike Mgbemena

25 Aug 2017

Kotlin

Next you’ll need to work on connecting Kotlin to Android, and the Get Started Coding Android Apps with Kotlin does just that. Covering things like Android views, layouts, inputs, and navigation, you’ll be well on your way to creating your first simple app by the time you’re through.

Kotlin

Get Started Coding Android Apps With Kotlin

Annapurna Agrawal

Working with App Templates

Once you’ve built a few of your own simple apps, it’s time to move onto more advanced concepts. There are plenty of mid-level tutorials out there, but one of the best moves to is to look at existing apps, and try to break down how they work.

Whether you want to look at popular open source apps, or some of the best Android app templates available over on CodeCanyon, there’s plenty of code to start with.

App Templates

20 Best Android App Templates of 2020

Franc Lucas

Take a look at the app you’ve chosen, and try to break it down into its components. How are they displaying the layout of a particular screen? How did they get the login function to work? What are they doing to make user profiles available?

Analyzing each of these sections, and anything else that interests you about the app will help you to understand how that type of function is built. Even more useful though is that you can see it in action by building the app and fiddling with the code.

Can you adjust the template to display things differently? Can you re-theme it to match how you’d like an app to look? Can you add a new piece of functionality to the template?

Working through these questions will give you hands on experience on making your way through these tasks. If you run into any issues, make sure to reach out to the community for help!

You can read more about how to use an Android app template here on Envato Tuts+.

Android

Build a 360-Degree Video Player App With an Android App Template

Esther Vaati

Android

Best Free Android Apps and How to Create Them Yourself

Ashraff Hathibelagal

Expanding Your App Development Skills

You’re starting to branch out with your Android development now, building basic apps and extending them using existing pieces. But where do you go next? Next up is expanding on your fundamentals, learning more about the capabilities of Kotlin, Android, and the interactions between them.

Learning more about Android Activities will help you to create more robust user interfaces. By looking into activities in more depth, you’ll get a handle advanced listening for activity events, how to navigate between activities, and how to share data between them.

Android

Android Fundamentals: Activities

Annapurna Agrawal

You might also want to flesh out your understanding for concepts such as intents and services as well. Intents can act as the glue holding the components of your app together, and the course Kotlin Android Fundamentals: Intents will help you to understand them inside and out. To expand your knowledge on services, the course Kotlin Android Fundamentals: Services will help you out. Covering foreground and background services, and their implementation, this course is a must-have for anyone looking to develop Android apps.

Android

Kotlin Android Fundamentals: Intents

Annapurna Agrawal

Android

Kotlin Android Fundamentals: Services

Annapurna Agrawal

Once you’ve explored the more in-depth portions of the fundamentals, it’s time to move on to some of the more advanced aspects of Android app development.

Advanced Android App Development

Once you get into the more advanced areas of any type of programming, things inevitably get more niche. If you have a specific area that you’d like to improve, the Android Development content category here on Tuts+ can be a great start. With 200+ tutorials and 20+ courses, most topics have enough coverage to help you decide where to go next.

For example, you can learn how to code a professional looking navigation bar:

Android SDK

How to Code a Navigation Drawer for an Android App

Chike Mgbemena

You can learn how to connect to a REST API with the Retrofit library:

Android SDK

Sending Data With Retrofit 2 HTTP Client for Android

Chike Mgbemena

And there are lots of examples of how to code a complete app. For example, you can learn how to build a complete chat app that connects to Firebase:

Android SDK

How to Create an Android Chat App Using Firebase

Ashraff Hathibelagal

Finally, if you’re more into optimization, 8 Ways to Reduce Your Android App APK Size covers some interesting aspects of what goes into your app’s final size.

Android SDK

8 Ways to Reduce Your Android App APK Size

Jessica Thornsby

Learn to Create Apps With Android App Templates from CodeCanyon

A great way to get started coding Android apps is with an app template from CodeCanyon. CodeCanyon is an online marketplace that has hundreds of templates for every kind of app. You can save days, even months, of effort by using one of them. And since the app templates come with full source code, you can learn how to create all sorts of different kinds of apps by reading the source.

If you have trouble deciding which template on CodeCanyon is right for you, these articles should help:

App Templates

20 Best Android App Templates of 2020

Franc Lucas

Android SDK

10 Best Android Game Templates

Ashraff Hathibelagal

App Templates

15 Best eCommerce Android App Templates

Daniel Strongin

Material Design

Best Material Design Android App Templates

Nona Blackman

by Kyle Sloka-Frey via Envato Tuts+ Code https://ift.tt/2KxOWYu

#CSS3 #HTML5 Branding #HTML5 Weekly #HTMLl5 demos #Javascript #Javascript Branding #Javascript Weekly

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techndeck-blog · 6 years ago

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TakeWhile & DropWhile in Java 9 Streams with Examples

One of the most significant features introduced in Java 8 was Streams API. Since then, as Streams is on demand, later releases also focuses on improving or adding the news features in the same. That's where 2 more Stream operations came into picture with the release of Java 9. Here are we going to see two more collections that have been added as part of the Java 9 release i.e DropWhile & TakeWhile.

In this tutorial, we are going to cover below topics: What is takeWhile & dropWhile operations in Streams? How to implement it with example?

1. What is takeWhile & dropWhile operations in Streams?

takeWhile takeWhile expects a predicate and returns a new stream consisting only of the elements that match the given predicate. But, it classifying among three different cases. Let's understand all of them, If the stream is Ordered: It returns a stream consisting of the longest prefix of elements taken from this stream that match the given predicate. If this stream is ordered then the longest prefix is a contiguous sequence of elements of this stream that match the given predicate. The first element of the sequence is the first element of this stream, and the element immediately following the last element of the sequence does not match the given predicate. Stream.of(1, 3, 5, 7, 9, 13, 16, 17, 19) .takeWhile(e -> e % 2 != 0) .forEach(e -> System.out.println(e)); // Output: // 1 // 3 // 5 // 7 // 9 // 13 If you notice above, 17 & 19 are also matching the predicate but because 16 is not matching, therefore, the returning stream won't consider 17 and 19 and just cut off at the failing element. If the stream is Un-Ordered: It returns a stream consisting of a subset of elements taken from this stream that match the given predicate. If this stream is unordered, and some (but not all) elements of this stream match the given predicate, then the behavior of this operation is nondeterministic; it is free to take any subset of matching elements(which includes the empty set). Set numbers = Set.of(1,3,5,2,7); numbers.stream() .takeWhile(e -> e % 2 != 0) .forEach(e -> System.out.println(e)); // Now, you can see different out all the time Or even there can be an empty set If the stream is independent of whether ordered or un0rdered (Matching all elements OR Matching none of the element): If all elements of this stream match the given predicate then this operation takes all elements means the output is same as input, or if no elements of the stream match the given predicate then no elements are taken then the output is an empty steam. Set numbers = Set.of(25, 75, 100, 125, 150); numbers.stream() .takeWhile(n -> n % 5 == 0) .forEach(e -> System.out.println(e)); // Your can always see the same result 75 125 100 150 25 as input But the order could be non deterministic Set numbers = Set.of(25, 75, 100, 125, 150); numbers.Stream .takeWhile(n -> n % 5 != 0) .forEach(e -> System.out.println(e)); // It will print out nothing

dropWhile dropWhile is the opposite of takeWhile. dropWhile drops the elements which is matching to the predicate instead of taking them as takeWhile. And, whenever it reaches to the element which does not match the predicate, it includes the remaining elements in the returned stream. Stream.of(1,3,5,7,9,13,16,17,19) .dropWhile(e -> e % 2 != 0) .forEach(e -> System.out.println(e)); // Output: // 16 // 17 // 19

2. takeWhile & dropWhile implementation example

import java.util.*; public class TakeWhile_Java9_Example { public static void main(String args) { List OrderedList = Arrays.asList(1, 3, 5, 7, 9, 13, 16, 17, 19); Set UnorderedList = Set.of(1, 3, 5, 2, 7); Set IndependentList = Set.of(25, 75, 100, 125, 150); //takeWhile //Ordered Stream Example System.out.println("takeWhile - Ordered"); OrderedList.stream() .takeWhile(e -> e % 2 != 0) .forEach(e -> System.out.println(e)); //Unordered Stream Example System.out.println("\ntakeWhile - Unordered"); UnorderedList.stream() .takeWhile(e -> e % 2 != 0) .forEach(System.out::println); //Independent Stream Example (When all elements are matching) System.out.println("\ntakeWhile - Independent (all elements matching)"); IndependentList.stream() .takeWhile(e -> e % 5 == 0) .forEach(System.out::println); //Independent Stream Example (When none of the element is matching) System.out.println("\ntakeWhile - Independent (none of the element matching)"); IndependentList.stream() .takeWhile(e -> e .forEach(System.out::println); //dropWhile //Ordered Stream Example System.out.println("\ndropWhile - Ordered"); OrderedList.stream() .dropWhile(e -> e % 2 != 0) .forEach(e -> System.out.println(e)); } } Output: takeWhile - Ordered 1 3 5 7 9 13 takeWhile - Unordered 7 5 3 takeWhile - Independent (all elements matching) 125 75 25 150 100 takeWhile - Independent (none of the element matching) dropWhile - Ordered 16 17 19 takeWhile & dropWhile are truly useful addition as part of Streams in Java 9 and can serve variety of purposes. I hope above examples could help you to get better idea on how to implement it. Do you like this Post? – then check my other helpful posts: Passing Function as a Parameter in another Method in Java 8 Collection sorting using Lambda in Java 8 Generate Prime numbers in Java 8 Other Useful References: java.util.stream by Oracle Java 8 Stream by Baeldung Read the full article

#Java9

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siva3155 · 6 years ago

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JAVA Interview Questions and Answers

java interview questions for freshers experienced developers

1. What is Java? Java is a object-oriented programming language originally developed by Sun Micro systems and released in 1995. Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX. 2. What are the supported platforms by Java Programming Language? Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX/Linux like HP-Unix, Sun Solaris, Red hat Linux, Ubuntu, Cent OS, etc. 3. List any five features of Java? Some features include Object Oriented Platform Independent Robust Interpreted Multi-threaded 4. Why is Java Architectural Neutral? It’s compiler generates an architecture-neutral object file format, which makes the compiled code to be executable on many processors, with the presence of Java runtime system. 5. What is a singleton class? Give a practical example of its usage. A singleton class in java can have only one instance and hence all its methods and variables belong to just one instance. Singleton class concept is useful for the situations when there is a need to limit the number of objects for a class. The best example of singleton usage scenario is when there is a limit of having only one connection to a database due to some driver limitations or because of any licensing issues. 6. What are the access modifiers in Java? There are 3 access modifiers. Public, protected and private, and the default one if no identifier is specified is called friendly, but programmer cannot specify the friendly identifier explicitly. 7. What is are packages? A package is a collection of related classes and interfaces providing access protection and namespace management. 8. What is meant by Inheritance and What are its advantages? Inheritance is the process of inheriting all the features from a class. The advantages of inheritance are reusability of code and accessibility of variables and methods of the super class by subclasses. 9. What is the difference between superclass and subclass? A super class is a class that is inherited whereas sub class is a class that does the inheriting. 10. What is an abstract class? An abstract class is a class designed with implementation gaps for subclasses to fill in and is deliberately incomplete.

JAVA Interview Questions 11. What are the states associated in the thread? Thread contains ready, running, waiting and dead states. 12. What is synchronization? Synchronization is the mechanism that ensures that only one thread is accessed the resources at a time. 13. What is deadlock? When two threads are waiting each other and can’t precede the program is said to be deadlock. 14. What is an applet? Applet is a dynamic and interactive program that runs inside a web page displayed by a java capable browser 15. What is the lifecycle of an applet? init() method - Can be called when an applet is first loaded start() method - Can be called each time an applet is started. paint() method - Can be called when the applet is minimized or maximized. stop() method - Can be used when the browser moves off the applet’s page. destroy() method - Can be called when the browser is finished with the applet. 16. Define How do you set security in applets? using setSecurityManager() method 17. What is a layout manager and What are different types of layout managers available in java AWT? A layout manager is an object that is used to organize components in a container. The different layouts are available are FlowLayout, BorderLayout, CardLayout, GridLayout and GridBagLayout 18. What is JDBC? JDBC is a set of Java API for executing SQL statements. This API consists of a set of classes and interfaces to enable programs to write pure Java Database applications. 19. What are drivers available? JDBC-ODBC Bridge driver Native API Partly-Java driver JDBC-Net Pure Java driver Native-Protocol Pure Java driver 20. What is stored procedure? Stored procedure is a group of SQL statements that forms a logical unit and performs a particular task. Stored Procedures are used to encapsulate a set of operations or queries to execute on database. Stored procedures can be compiled and executed with different parameters and results and may have any combination of input/output parameters. 21. What is the Java API? The Java API is a large collection of ready-made software components that provide many useful capabilities, such as graphical user interface (GUI) widgets. 22. Why there are no global variables in Java? Global variables are globally accessible. Java does not support globally accessible variables due to following reasons: The global variables breaks the referential transparency Global variables creates collisions in namespace. 23. What are Encapsulation, Inheritance and Polymorphism? Encapsulation is the mechanism that binds together code and data it manipulates and keeps both safe from outside interference and misuse. Inheritance is the process by which one object acquires the properties of another object. Polymorphism is the feature that allows one interface to be used for general class actions. 24. What is the use of bin and lib in JDK? Bin contains all tools such as javac, appletviewer, awt tool, etc., whereas lib contains API and all packages. 25. What is method overloading and method overriding? Method overloading: When a method in a class having the same method name with different arguments is said to be method overloading. Method overriding : When a method in a class having the same method name with same arguments is said to be method overriding. 26. What is the difference between this() and super()? this() can be used to invoke a constructor of the same class whereas super() can be used to invoke a super class constructor. 27. What is Domain Naming Service(DNS)? It is very difficult to remember a set of numbers(IP address) to connect to the Internet. The Domain Naming Service(DNS) is used to overcome this problem. It maps one particular IP address to a string of characters. For example, www. mascom. com implies com is the domain name reserved for US commercial sites, moscom is the name of the company and www is the name of the specific computer, which is mascom’s server. 28. What is URL? URL stands for Uniform Resource Locator and it points to resource files on the Internet. URL has four components: http://www. address. com:80/index.html, where http - protocol name, address - IP address or host name, 80 - port number and index.html - file path. 29. What is RMI and steps involved in developing an RMI object? Remote Method Invocation (RMI) allows java object that executes on one machine and to invoke the method of a Java object to execute on another machine. The steps involved in developing an RMI object are: a) Define the interfaces b) Implementing these interfaces c) Compile the interfaces and their implementations with the java compiler d) Compile the server implementation with RMI compiler e) Run the RMI registry f) Run the application. 30. What is RMI architecture? RMI architecture consists of four layers and each layer performs specific functions: a) Application layer - contains the actual object definition. b) Proxy layer - consists of stub and skeleton. c) Remote Reference layer - gets the stream of bytes from the transport layer and sends it to the proxy layer. d) Transportation layer - responsible for handling the actual machine-to-machine communication. 31. What is a Java Bean? A Java Bean is a software component that has been designed to be reusable in a variety of different environments. 32. What are checked exceptions? Checked exception are those which the Java compiler forces you to catch. e.g. IOException are checked Exceptions. 33. What are runtime exceptions? Runtime exceptions are those exceptions that are thrown at runtime because of either wrong input data or because of wrong business logic etc. These are not checked by the compiler at compile time. 34. What is the difference between error and an exception? An error is an irrecoverable condition occurring at runtime. Such as OutOfMemory error. These JVM errors and you can not repair them at runtime. While exceptions are conditions that occur because of bad input etc. e.g. FileNotFoundException will be thrown if the specified file does not exist. Or a NullPointerException will take place if you try using a null reference. In most of the cases it is possible to recover from an exception (probably by giving user a feedback for entering proper values etc.). 35. What is the purpose of finalization? The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected. For example, closing a opened file, closing a opened database Connection. 36. What is the difference between yielding and sleeping? When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state. 37. What is the difference between preemptive scheduling and time slicing? Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors. 38. What is mutable object and immutable object? If a object value is changeable then we can call it as Mutable object. (Ex., StringBuffer, …) If you are not allowed to change the value of an object, it is immutable object. (Ex., String, Integer, Float, …) 39. What is the purpose of Void class? The Void class is an uninstantiable placeholder class to hold a reference to the Class object representing the primitive Java type void. 40. What is JIT and its use? Really, just a very fast compiler… In this incarnation, pretty much a one-pass compiler — no offline computations. So you can’t look at the whole method, rank the expressions according to which ones are re-used the most, and then generate code. In theory terms, it’s an on-line problem. 41. What is nested class? If all the methods of a inner class is static then it is a nested class. 42. What is HashMap and Map? Map is Interface and Hashmap is class that implements that. 43. What are different types of access modifiers? public: Any thing declared as public can be accessed from anywhere. private: Any thing declared as private can’t be seen outside of its class. protected: Any thing declared as protected can be accessed by classes in the same package and subclasses in the other packages. default modifier : Can be accessed only to classes in the same package. 44. What is the difference between Reader/Writer and InputStream/Output Stream? The Reader/Writer class is character-oriented and the InputStream/OutputStream class is byte-oriented. 45. What is servlet? Servlets are modules that extend request/response-oriented servers, such as java-enabled web servers. For example, a servlet might be responsible for taking data in an HTML order-entry form and applying the business logic used to update a company’s order database. 46. What is Constructor? A constructor is a special method whose task is to initialize the object of its class. It is special because its name is the same as the class name. They do not have return types, not even void and therefore they cannot return values. They cannot be inherited, though a derived class can call the base class constructor. Constructor is invoked whenever an object of its associated class is created. 47. What is an Iterator ? The Iterator interface is used to step through the elements of a Collection. Iterators let you process each element of a Collection. Iterators are a generic way to go through all the elements of a Collection no matter Define How it is organized. Iterator is an Interface implemented a different way for every Collection. 48. What is the List interface? The List interface provides support for ordered collections of objects. Lists may contain duplicate elements. 49. What is memory leak? A memory leak is where an unreferenced object that will never be used again still hangs around in memory and doesnt get garbage collected. 50. What is the difference between the prefix and postfix forms of the ++ operator? The prefix form performs the increment operation and returns the value of the increment operation. The postfix form returns the current value all of the expression and then performs the increment operation on that value. 51. What is the difference between a constructor and a method? A constructor is a member function of a class that is used to create objects of that class. It has the same name as the class itself, has no return type, and is invoked using the new operator. A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator. 52. What will happen to the Exception object after exception handling? Exception object will be garbage collected. 53. Difference between static and dynamic class loading. Static class loading: The process of loading a class using new operator is called static class loading. Dynamic class loading: The process of loading a class at runtime is called dynamic class loading. Dynamic class loading can be done by using Class.forName(….).newInstance(). 54. Explain the Common use of EJB The EJBs can be used to incorporate business logic in a web-centric application. The EJBs can be used to integrate business processes in Business-to-business (B2B) e-commerce applications.In Enterprise Application Integration applications, EJBs can be used to house processing and mapping between different applications. 55. What is JSP? JSP is a technology that returns dynamic content to the Web client using HTML, XML and JAVA elements. JSP page looks like a HTML page but is a servlet. It contains Presentation logic and business logic of a web application. 56. What is the purpose of apache tomcat? Apache server is a standalone server that is used to test servlets and create JSP pages. It is free and open source that is integrated in the Apache web server. It is fast, reliable server to configure the applications but it is hard to install. It is a servlet container that includes tools to configure and manage the server to run the applications. It can also be configured by editing XML configuration files. 57. Where pragma is used? Pragma is used inside the servlets in the header with a certain value. The value is of no-cache that tells that a servlets is acting as a proxy and it has to forward request. Pragma directives allow the compiler to use machine and operating system features while keeping the overall functionality with the Java language. These are different for different compilers. 58. Briefly explain daemon thread. Daemon thread is a low priority thread which runs in the background performs garbage collection operation for the java runtime system. 59. What is a native method? A native method is a method that is implemented in a language other than Java. 60. Explain different way of using thread? A Java thread could be implemented by using Runnable interface or by extending the Thread class. The Runnable is more advantageous, when you are going for multiple inheritance. 61. What are the two major components of JDBC? One implementation interface for database manufacturers, the other implementation interface for application and applet writers. 62. What kind of thread is the Garbage collector thread? It is a daemon thread. 63. What are the different ways to handle exceptions? There are two ways to handle exceptions, By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and List the desired exceptions in the throws clause of the method and let the caller of the method handle those exceptions. 64. Define How many objects are created in the following piece of code? MyClass c1, c2, c3; c1 = new MyClass (); c3 = new MyClass (); Answer: Only 2 objects are created, c1 and c3. The reference c2 is only declared and not initialized. 65.What is UNICODE? Unicode is used for internal representation of characters and strings and it uses 16 bits to represent each other. 66. Can a constructor have different name than a Class name in Java? Constructor in Java must have same name as the class name and if the name is different, it doesn’t act as a constructor and compiler thinks of it as a normal method. 67. What will be the output of Round(3.7) and Ceil(3.7)? Round(3.7) returns 4 and Ceil(3.7) returns 4. 68: Can we use goto in Java to go to a particular line? In Java, there is not goto keyword and java doesn’t support this feature of going to a particular labeled line. 69. Can a dead thread be started again? In java, a thread which is in dead state can’t be started again. There is no way to restart a dead thread. 70. Is the following class declaration correct? public abstract final class testClass { // Class methods and variables } The above class declaration is incorrect as an abstract class can’t be declared as Final. 71. Is JDK required on each machine to run a Java program? JDK is development Kit of Java and is required for development only and to run a Java program on a machine, JDK isn’t required. Only JRE is required. 72. Which object oriented Concept is achieved by using overloading and overriding? Polymorphism 73. Is it possible to define a method in Java class but provide it’s implementation in the code of another language like C? Yes, we can do this by use of native methods. In case of native method based development, we define public static methods in our Java class without its implementation and then implementation is done in another language like C separately. 74. Define How destructors are defined in Java? In Java, there are no destructors defined in the class as there is no need to do so. Java has its own garbage collection mechanism which does the job automatically by destroying the objects when no longer referenced. 75. Can a variable be local and static at the same time? No a variable can’t be static as well as local at the same time. Defining a local variable as static gives compilation error. 76. Can we have static methods in an Interface? Static methods can’t be overridden in any class while any methods in an interface are by default abstract and are supposed to be implemented in the classes being implementing the interface. So it makes no sense to have static methods in an interface in Java. 77. In a class implementing an interface, can we change the value of any variable defined in the interface? No, we can’t change the value of any variable of an interface in the implementing class as all variables defined in the interface are by default public, static and Final and final variables are like constants which can’t be changed later. 78. Is it correct to say that due to garbage collection feature in Java, a java program never goes out of memory? Even though automatic garbage collection is provided by Java, it doesn’t ensure that a Java program will not go out of memory as there is a possibility that creation of Java objects is being done at a faster pace compared to garbage collection resulting in filling of all the available memory resources. So, garbage collection helps in reducing the chances of a program going out of memory but it doesn’t ensure that. 79. Can we have any other return type than void for main method? No, Java class main method can have only void return type for the program to get successfully executed. Nonetheless , if you absolutely must return a value to at the completion of main method , you can use System.exit(int status) 80. I want to re-reach and use an object once it has been garbage collected. Define How it’s possible? Once an object has been destroyed by garbage collector, it no longer exists on the heap and it can’t be accessed again. There is no way to reference it again. 81. In Java thread programming, which method is a must implementation for all threads? Run() is a method of Runnable interface that must be implemented by all threads. 82. I want to control database connections in my program and want that only one thread should be able to make database connection at a time. Define How can I implement this logic? This can be implemented by use of the concept of synchronization. Database related code can be placed in a method which hs synchronized keyword so that only one thread can access it at a time. 83. Can an Interface extend another Interface? Yes an Interface can inherit another Interface, for that matter an Interface can extend more than one Interface. 84. I want my class to be developed in such a way that no other class (even derived class) can create its objects. Define How can I do so? If we declare the constructor of a class as private, it will not be accessible by any other class and hence, no other class will be able to instantiate it and formation of its object will be limited to itself only. 85. Define How objects are stored in Java? In java, each object when created gets a memory space from a heap. When an object is destroyed by a garbage collector, the space allocated to it from the heap is re-allocated to the heap and becomes available for any new objects. 86. Define How can we find the actual size of an object on the heap? In java, there is no way to find out the exact size of an object on the heap. 87. Which of the following classes will have more memory allocated? Class Three methods, four variables, no object Class B: Five methods, three variables, no object Memory isn’t allocated before creation of objects. Since for both classes, there are no objects created so no memory is allocated on heap for any class. 88. What happens if an exception is not handled in a program? If an exception is not handled in a program using try catch blocks, program gets aborted and no statement executes after the statement which caused exception throwing. 89. I have multiple constructors defined in a class. Is it possible to call a constructor from another constructor’s body? If a class has multiple constructors, it’s possible to call one constructor from the body of another one using this(). 90. What’s meant by anonymous class? An anonymous class is a class defined without any name in a single line of code using new keyword. For example, in below code we have defined an anonymous class in one line of code: public java.util.Enumeration testMethod() { return new java.util.Enumeration() { @Override public boolean hasMoreElements() { // TODO Auto-generated method stub return false; } @Override public Object nextElement() { // TODO Auto-generated method stub return null; } 91. Is there a way to increase the size of an array after its declaration? Arrays are static and once we have specified its size, we can’t change it. If we want to use such collections where we may require a change of size ( no of items), we should prefer vector over array. 92. If an application has multiple classes in it, is it okay to have a main method in more than one class? If there is main method in more than one classes in a java application, it won’t cause any issue as entry point for any application will be a specific class and code will start from the main method of that particular class only. 93. I want to persist data of objects for later use. What’s the best approach to do so? The best way to persist data for future use is to use the concept of serialization. 94. What is a Local class in Java? In Java, if we define a new class inside a particular block, it’s called a local class. Such a class has local scope and isn’t usable outside the block where its defined. 95. String and StringBuffer both represent String objects. Can we compare String and StringBuffer in Java? Although String and StringBuffer both represent String objects, we can’t compare them with each other and if we try to compare them, we get an error. 96. Which API is provided by Java for operations on set of objects? Java provides a Collection API which provides many useful methods which can be applied on a set of objects. Some of the important classes provided by Collection API include ArrayList, HashMap, TreeSet and TreeMap. 97. Can we cast any other type to Boolean Type with type casting? No, we can neither cast any other primitive type to Boolean data type nor can cast Boolean data type to any other primitive data type. 98. What are synchronized methods and synchronized statements? Synchronized methods are methods that are used to control access to an object. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement. 99. Define How does a try statement determine which catch clause should be used to handle an exception? When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exception is executed. The remaining catch clauses are ignored. 100. What will be the default values of all the elements of an array defined as an instance variable? If the array is an array of primitive types, then all the elements of the array will be initialized to the default value corresponding to that primitive type. Basic JAVA Questions with Answers pdf download 101. What is the difference between static and non-static variables? A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance. 102. What is Serialization and deserialization? Serialization is the process of writing the state of an object to a byte stream. Deserialization is the process of restoring these objects. 103. What are use cases? It is part of the analysis of a program and describes a situation that a program might encounter and what behavior the program should exhibit in that circumstance. 104. Explain the use of sublass in a Java program? Sub class inherits all the public and protected methods and the implementation. It also inherits all the default modifier methods and their implementation. 105. How to add menushortcut to menu item? If there is a button instance called b1, you may add menu short cut by calling b1.setMnemonic('F'), so the user may be able to use Alt+F to click the button. 106. Can you write a Java class that could be used both as an applet as well as an application? Yes, just add a main() method to the applet. 107. What is the difference between Swing and AWT components? AWT components are heavy-weight, whereas Swing components are lightweight. Heavy weight components depend on the local windowing toolkit. For example, java.awt.Button is a heavy weight component, when it is running on the Java platform for Unix platform, it maps to a real Motif button. 108. What's the difference between constructors and other methods? Constructors must have the same name as the class and can not return a value. They are only called once while regular methods could be called many times. 109. Is there any limitation of using Inheritance? Yes, since inheritance inherits everything from the super class and interface, it may make the subclass too clustering and sometimes error-prone when dynamic overriding or dynamic overloading in some situation. 109. When is the ArrayStoreException thrown? When copying elements between different arrays, if the source or destination arguments are not arrays or their types are not compatible, an ArrayStoreException will be thrown. 110. Can you call one constructor from another if a class has multiple constructors? Yes, use this() syntax. 111. What's the difference between the methods sleep() and wait()? The code sleep(2000); puts thread aside for exactly two seconds. The code wait(2000), causes a wait of up to two second. A thread could stop waiting earlier if it receives the notify() or notifyAll() call. The method wait() is defined in the class Object and the method sleep() is defined in the class Thread. 112. When ArithmeticException is thrown? The ArithmeticException is thrown when integer is divided by zero or taking the remainder of a number by zero. It is never thrown in floating-point operations. 113. What is a transient variable? A transient variable is a variable that may not be serialized during Serialization and which is initialized by its default value during de-serialization, 114. What is synchronization? Synchronization is the capability to control the access of multiple threads to shared resources. synchronized keyword in java provides locking which ensures mutual exclusive access of shared resource and prevent data race. 115. What is the Collections API? The Collections API is a set of classes and interfaces that support operations on collections of objects. 116. Does garbage collection guarantee that a program will not run out of memory? Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection. 117. The immediate super class of the Applet class? Panel is the immediate super class. A panel provides space in which an application can attach any other component, including other panels. 118. Which Java operator is right associative? The = operator is right associative. 119. What is the difference between a break statement and a continue statement? A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement. 120. If a variable is declared as private, where may the variable be accessed? A private variable may only be accessed within the class in which it is declared. 121. What is the purpose of the System class? The purpose of the System class is to provide access to system resources. 122. List primitive Java types? The eight primitive types are byte, char, short, int, long, float, double, and boolean. 123. What is the relationship between clipping and repainting under AWT? When a window is repainted by the AWT painting thread, it sets the clipping regions to the area of the window that requires repainting. 124. Which class is the immediate superclass of the Container class? Component class is the immediate super class. 125. What class of exceptions are generated by the Java run-time system? The Java runtime system generates RuntimeException and Error exceptions. 126. Under what conditions is an object's finalize() method invoked by the garbage collector? The garbage collector invokes an object's finalize() method when it detects that the object has become unreachable. 127. How can a dead thread be restarted? A dead thread cannot be restarted. 128. Which arithmetic operations can result in the throwing of an ArithmeticException? Integer / and % can result in the throwing of an ArithmeticException. 129. Variable of the boolean type is automatically initialized as? The default value of the boolean type is false. 130. What are ClassLoaders? A class loader is an object that is responsible for loading classes. The class ClassLoader is an abstract class. 131. What is the difference between an Interface and an Abstract class? An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An interface has all public members and no implementation. 132. What will happen if static modifier is removed from the signature of the main method? Program throws "NoSuchMethodError" error at runtime . 133. Can try statements be nested? Yes 134. What is the default value of an object reference declared as an instance variable? Null, unless it is defined explicitly. 135. Can a top level class be private or protected? No, a top level class can not be private or protected. It can have either "public" or no modifier. 136. Why do we need wrapper classes? We can pass them around as method parameters where a method expects an object. It also provides utility methods. 137. What is the difference between error and an exception? An error is an irrecoverable condition occurring at runtime. Such as OutOfMemory error. Exceptions are conditions that occur because of bad input etc. e.g. FileNotFoundException will be thrown if the specified file does not exist. 138. Is it necessary that each try block must be followed by a catch block? It is not necessary that each try block must be followed by a catch block. It should be followed by either a catch block or a finally block. 139. When a thread is created and started, what is its initial state? A thread is in the ready state as initial state after it has been created and started. 140. What is the Locale class? The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region. 141. What are synchronized methods and synchronized statements? Synchronized methods are methods that are used to control access to an object. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement. 142. What is runtime polymorphism or dynamic method dispatch? Runtime polymorphism or dynamic method dispatch is a process in which a call to an overridden method is resolved at runtime rather than at compile-time. In this process, an overridden method is called through the reference variable of a superclass. 143. What is Dynamic Binding(late binding)? Binding refers to the linking of a procedure call to the code to be executed in response to the call. Dynamic binding means that the code associated with a given procedure call is not known until the time of the call at run-time. 144. Can constructor be inherited? No, constructor cannot be inherited. 145. What are the advantages of ArrayList over arrays? ArrayList can grow dynamically and provides more powerful insertion and search mechanisms than arrays. 146. Why deletion in LinkedList is fast than ArrayList? Deletion in linked list is fast because it involves only updating the next pointer in the node before the deleted node and updating the previous pointer in the node after the deleted node. 147. How do you decide when to use ArrayList and LinkedList? If you need to frequently add and remove elements from the middle of the list and only access the list elements sequentially, then LinkedList should be used. If you need to support random access, without inserting or removing elements from any place other than the end, then ArrayList should be used. 148. What is a Values Collection View ? It is a collection returned by the values() method of the Map Interface, It contains all the objects present as values in the map. 149. What is dot operator? The dot operator(.) is used to access the instance variables and methods of class objects.It is also used to access classes and sub-packages from a package. 150. Where and how can you use a private constructor? Private constructor is used if you do not want other classes to instantiate the object and to prevent subclassing.T 151. What is type casting? Type casting means treating a variable of one type as though it is another type. Q: Describe life cycle of thread? A thread is a execution in a program. The life cycle of a thread include:Newborn state Runnable state Running state Blocked state Dead state 152. What is the difference between the >> and >>> operators? The >> operator carries the sign bit when shifting right. The >>> zero-fills bits that have been shifted out. 153. Which method of the Component class is used to set the position and size of a component? setBounds() method is used for this purpose. 154. What is the range of the short type? The range of the short type is -(2^15) to 2^15 - 1. 155. What is the immediate superclass of Menu? MenuItem class 156. Does Java allow Default Arguments? No, Java does not allow Default Arguments. 157. Which number is denoted by leading zero in java? Octal Numbers are denoted by leading zero in java, example: 06 158. Which number is denoted by leading 0x or 0X in java? Hexadecimal Numbers are denoted by leading 0x or 0X in java, example: 0XF 159. Break statement can be used as labels in Java? Yes, an example can be break one; 160. Where import statement is used in a Java program? Import statement is allowed at the beginning of the program file after package statement. 161. Explain suspend() method under Thread class> It is used to pause or temporarily stop the execution of the thread. 162. Explain isAlive() method under Thread class? It is used to find out whether a thread is still running or not. 163. What is currentThread()? It is a public static method used to obtain a reference to the current thread. 164. Explain main thread under Thread class execution? The main thread is created automatically and it begins to execute immediately when a program starts. It ia thread from which all other child threads originate. 165. Life cycle of an applet includes which steps? Life cycle involves the following steps: Initialization Starting Stopping Destroying Painting 166. Why is the role of init() method under applets? It initializes the applet and is the first method to be called. 167. Which method is called by Applet class to load an image? getImage(URL object, filename) is used for this purpose. 168. Define code as an attribute of Applet? It is used to specify the name of the applet class. 169. Define canvas? It is a simple drawing surface which are used for painting images or to perform other graphical operations. 170. Define Network Programming? It refers to writing programs that execute across multiple devices (computers), in which the devices are all connected to each other using a network. 171. What is a Socket? Sockets provide the communication mechanism between two computers using TCP. A client program creates a socket on its end of the communication and attempts to connect that socket to a server. 172. Advantages of Java Sockets? Sockets are flexible and sufficient. Efficient socket based programming can be easily implemented for general communications. It cause low network traffic. 173. Disadvantages of Java Sockets? Socket based communications allows only to send packets of raw data between applications. Both the client-side and server-side have to provide mechanisms to make the data useful in any way. 174. Which class is used by server applications to obtain a port and listen for client requests? java.net.ServerSocket class is used by server applications to obtain a port and listen for client requests 175. Which class represents the socket that both the client and server use to communicate with each other? java.net.Socket class represents the socket that both the client and server use to communicate with each other. 176. Why Generics are used in Java? Generics provide compile-time type safety that allows programmers to catch invalid types at compile time. Java Generic methods and generic classes enable programmers to specify, with a single method declaration, a set of related methods or, with a single class declaration, a set of related types. 177. What environment variables do I need to set on my machine in order to be able to run Java programs? CLASSPATH and PATH are the two variables. 178. Is there any need to import java.lang package? No, there is no need to import this package. It is by default loaded internally by the JVM. 179. What is Nested top-level class? If a class is declared within a class and specify the static modifier, the compiler treats the class just like any other top-level class. Nested top-level class is an Inner class. 180. What is Externalizable interface? Externalizable is an interface which contains two methods readExternal and writeExternal. These methods give you a control over the serialization mechanism. 181. If System.exit (0); is written at the end of the try block, will the finally block still execute? No in this case the finally block will not execute because when you say System.exit (0); the control immediately goes out of the program, and thus finally never executes. 182. What is daemon thread? Daemon thread is a low priority thread, which runs intermittently in the back ground doing the garbage collection operation for the java runtime system. 183. Which method is used to create the daemon thread? setDaemon method is used to create a daemon thread. 184. Which method must be implemented by all threads? All tasks must implement the run() method 185. What is the GregorianCalendar class? The GregorianCalendar provides support for traditional Western calendars 186. What is the SimpleTimeZone class? The SimpleTimeZone class provides support for a Gregorian calendar . 187. What is the difference between the size and capacity of a Vector? The size is the number of elements actually stored in the vector, while capacity is the maximum number of elements it can store at a given instance of time. 188. Can a vector contain heterogenous objects? Yes a Vector can contain heterogenous objects. Because a Vector stores everything in terms of Object. 189. What is an enumeration? An enumeration is an interface containing methods for accessing the underlying data structure from which the enumeration is obtained. It allows sequential access to all the elements stored in the collection. 190. What is difference between Path and Classpath? Path and Classpath are operating system level environment variales. Path is defines where the system can find the executables(.exe) files and classpath is used to specify the location of .class files. 191. Can a class declared as private be accessed outside it's package? No, it's not possible to accessed outside it's package. 192. What are the restriction imposed on a static method or a static block of code? A static method should not refer to instance variables without creating an instance and cannot use "this" operator to refer the instance. 240. Can an Interface extend another Interface? Yes an Interface can inherit another Interface, for that matter an Interface can extend more than one Interface. 241. Which object oriented Concept is achieved by using overloading and overriding? Polymorphism 242. What is an object's lock and which object's have locks? An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock. 243. What is Downcasting? It is the casting from a general to a more specific type, i.e. casting down the hierarchy. 244. What are order of precedence and associativity and how are they used? Order of precedence determines the order in which operators are evaluated in expressions. Associatity determines whether an expression is evaluated left-to-right or right-to-left. 245. If a method is declared as protected, where may the method be accessed? A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared. 246. What is the difference between inner class and nested class? When a class is defined within a scope of another class, then it becomes inner class. If the access modifier of the inner class is static, then it becomes nested class. 247. What restrictions are placed on method overriding? Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides. 248. What is constructor chaining and how is it achieved in Java? A child object constructor always first needs to construct its parent. In Java it is done via an implicit call to the no-args constructor as the first statement. 249. Can a double value be cast to a byte? Yes, a double value can be cast to a byte. 250. How does a try statement determine which catch clause should be used to handle an exception? When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exception is executed. The remaining catch clauses are ignored. 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