#treemap | Explore Tumblr posts and blogs

praveennareshit · 1 month ago

Text

📚 Comparing Java Collections: Which Data Structure Should You Use?

If you're diving into Core Java, one thing you'll definitely bump into is the Java Collections Framework. From storing a list of names to mapping users with IDs, collections are everywhere. But with all the options like List, Set, Map, and Queue—how do you know which one to pick? 🤯

Don’t worry, I’ve got you covered. Let’s break it down in simple terms, so you can make smart choices for your next Java project.

🔍 What Are Java Collections, Anyway?

The Java Collection Framework is like a big toolbox. Each tool (or data structure) helps you organize and manage your data in a specific way.

Here's the quick lowdown:

List – Ordered, allows duplicates

Set – Unordered, no duplicates

Map – Key-value pairs, keys are unique

Queue – First-In-First-Out (FIFO), or by priority

📌 When to Use What? Let’s Compare!

📝 List – Perfect for Ordered Data

Wanna keep things in order and allow duplicates? Go with a List.

Popular Types:

ArrayList – Fast for reading, not so much for deleting/inserting

LinkedList – Good for frequent insert/delete

Vector – Thread-safe but kinda slow

Stack – Classic LIFO (Last In, First Out)

Use it when:

You want to access elements by index

Duplicates are allowed

Order matters

Code Snippet:

java

🚫 Set – When You Want Only Unique Stuff

No duplicates allowed here! A Set is your go-to when you want clean, unique data.

Popular Types:

HashSet – Super fast, no order

LinkedHashSet – Keeps order

TreeSet – Sorted, but a bit slower

Use it when:

You care about uniqueness

You don’t mind the order (unless using LinkedHashSet)

You want to avoid duplication issues

Code Snippet:

java

🧭 Map – Key-Value Power Couple

Think of a Map like a dictionary. You look up values by their unique keys.

Popular Types:

HashMap – Fastest, not ordered

LinkedHashMap – Keeps insertion order

TreeMap – Sorted keys

ConcurrentHashMap – Thread-safe (great for multi-threaded apps)

Use it when:

You need to pair keys with values

You want fast data retrieval by key

Each key should be unique

Code Snippet:

java

⏳ Queue – For First-Come-First-Serve Vibes

Need to process tasks or requests in order? Use a Queue. It follows FIFO, unless you're working with priorities.

Popular Types:

LinkedList (as Queue) – Classic FIFO

PriorityQueue – Sorted based on priority

ArrayDeque – No capacity limit, faster than LinkedList

ConcurrentLinkedQueue – Thread-safe version

Use it when:

You’re dealing with task scheduling

You want elements processed in the order they come

You need to simulate real-life queues (like print jobs or tasks)

Code Snippet:

java

🧠 Cheat Sheet: Pick Your Collection Wisely

⚙️ Performance Talk: Behind the Scenes

💡 Real-Life Use Cases

Use ArrayList for menu options or dynamic lists.

Use HashSet for email lists to avoid duplicates.

Use HashMap for storing user profiles with IDs.

Use Queue for task managers or background jobs.

🚀 Final Thoughts: Choose Smart, Code Smarter

When you're working with Java Collections, there’s no one-size-fits-all. Pick your structure based on:

What kind of data you’re working with

Whether duplicates or order matter

Performance needs

The better you match the collection to your use case, the cleaner and faster your code will be. Simple as that. 💥

Got questions? Or maybe a favorite Java collection of your own? Drop a comment or reblog and let’s chat! ☕💻

If you'd like me to write a follow-up on concurrent collections, sorting algorithms, or Java 21 updates, just say the word!

✌️ Keep coding, keep learning! For More Info : Core Java Training in KPHB For UpComing Batches : https://linktr.ee/NIT_Training

0 notes

processes · 2 months ago

Text

Small multiple treemaps showing "for the United States and for each state, with distinction of sex, the ratio between the total population over 10 years of age and the number of persons reported as engaged in each principal class of gainful occupations and also as attending school, compiled from the returns of population at the Ninth Census 1870." From Statistical Atlas Of The United States based on the results of the Ninth Census 1870, as reproduced in Fraser's Federal Reserve Archive.

Francis A. Walker

0 notes

visual-sculptors · 3 months ago

Text

Comparing Treemaps and Mekko Charts: Choosing the Right Visualization for Your Data

Data Visualization: Frequently Asked Inquiries Explained

1.What is a Mekko chart format?

A Mekko chart, also known as a Marimekko chart, is a visual representation that displays categorical data with varying widths and heights. It combines features of a bar chart and a stacked column chart, allowing for the comparison of different categories and subcategories in terms of size and proportion. This format effectively illustrates market share, revenue, or other metrics.

2. How to make mekko chart in PPT?

To create a Mekko chart in PowerPoint, follow these steps:

1. Insert a blank slide.

2. Use the "Insert" tab, select "SmartArt," and choose a suitable layout.

3. Manually adjust the sizes of rectangles to represent data proportions.

4. Add text and labels to each section.

5. Customize colors and styles as needed for clarity and presentation.

3. What are the benefits of a Mekko chart?

A Mekko chart visually represents data across two dimensions, allowing for easy comparison of categories and subcategories. It effectively displays market share and growth potential, helping identify opportunities and trends. Its clear layout aids in decision-making and presentations, making complex data more accessible and understandable for stakeholders.

4. What is the difference between Tree map and Mekko chart?

A Tree map displays hierarchical data using nested rectangles, showing proportions through size and color. In contrast, a Mekko chart (or Marimekko chart) combines bar and area charts to represent categorical data with variable width bars and varying heights, illustrating both market share and category size. Essentially, Tree maps focus on hierarchy, while Mekko charts emphasize categorical comparisons.

5. How do you add a second Y axis in Mekko Graphics?

To add a second Y axis in Mekko Graphics, select your chart, go to the “Format” menu, and choose “Axes.” Then, enable the secondary Y axis option. You can customize its scale and labels as needed. This allows you to display two different data series with distinct Y axes for better comparison and analysis.

Visit: VS Website See: VS Portfolio

#MekkoChart #DataVisualization #PowerPointTips #BusinessAnalysis

0 notes

programming-tips · 3 months ago

Text

I have posted an article for Chinese.

#programming #java

0 notes

datarep · 2 years ago

Photo

Hispanic Heritage Hues: Treemap of color distribution of Latin American flags

by u/Metalytiq

#data #dataviz #Metalytiq

14 notes · View notes

excelrsolutionshyderabad · 3 months ago

Text

Data Analyst Course and Storytelling: Creating Impactful Dashboards and Charts Using Tools Like Tableau and Power BI

In the modern data-driven world, raw data is only as valuable as the insights derived from it. For businesses, conveying these insights in an impactful and comprehensible way is critical for decision-making. This is where the art of storytelling in data analysis comes into play. A dedicated module on data visualisation and storytelling in a Data Analyst Course in Nagpur equips professionals to create impactful dashboards and charts using industry-leading tools like Tableau and Power BI.

The Role of Storytelling in Data Analysis

Storytelling in data analysis involves transforming complex datasets into visually compelling narratives that resonate with stakeholders. It bridges the gap that creeps in between data insights and actionable business strategies. Key components of effective data storytelling include:

Clarity: Simplifying complex information for easy comprehension.

Context: Providing relevant background to make data meaningful.

Engagement: Using visuals to capture and hold attention.

Actionability: Delivering insights that lead to informed decisions.

Why Focus on Dashboards and Charts?

Dashboards and charts serve as the backbone of data storytelling. They provide an interactive and visual medium to:

Monitor key performance indicators (KPIs).

Track trends and patterns over time.

Highlight anomalies and areas requiring attention.

Support data-driven decision-making with clarity and precision.

Key Features of Tableau and Power BI

Tableau:

Renowned for its user-friendly interface and powerful visualisation capabilities.

Allows integration with multiple sources of data for comprehensive analysis.

Offers advanced features like drag-and-drop functionality, real-time data updates, and storytelling dashboards.

Supports interactive visualisations like heatmaps, treemaps, and scatter plots.

Power BI:

A robust Microsoft tool that integrates seamlessly with Office 365 and other Microsoft products.

Provides AI-driven insights and natural language querying.

Offers a wide range of visual templates and customisation options.

Ideal for creating enterprise-grade reports and dashboards.

Course Highlights: Mastering Visualisation Tools

A Data Analyst Course focusing on storytelling and visualisation covers the following key areas:

Data Preparation and Cleaning:

Importing, cleaning, and organising datasets for visualisation.

Handling large and disparate data sources.

Designing Dashboards:

Principles of effective dashboard design: layout, colour theory, and usability.

Building interactive and dynamic dashboards in Tableau and Power BI.

Charting Techniques:

Selecting the right chart type for the data and audience.

Creating advanced visualisations like histograms, box plots, and waterfall charts.

Storytelling Frameworks:

Structuring narratives around visualisations.

Using annotations, highlights, and sequences to guide the audience.

Real-World Projects:

Hands-on experience with industry-relevant datasets.

Creating end-to-end dashboards addressing business scenarios.

Benefits of Mastering Data Storytelling

Professionals trained in data storytelling with tools like Tableau and Power BI can:

Communicate insights effectively and efficiently to both technical and non-technical audiences.

Drive strategic decisions with data-backed narratives.

Enhance their employability in industries prioritising data-driven approaches.

Build visually engaging reports that foster collaboration and understanding.

Conclusion

A Data Analyst Course in Nagpur emphasising storytelling and visualisation is essential for anyone aiming to excel in today’s data-centric roles. By mastering tools like Tableau and Power BI, participants can create dashboards and charts that not only inform but inspire action. This skillset ensures that data analysis evolves from mere number crunching to impactful decision-making support.

0 notes

subb01 · 6 months ago

Text

Top Java Interview Questions You Should Know

Preparing for a Java interview can be daunting, especially when you're unsure of what to expect. Mastering common Java questions is crucial for making a lasting impression. This blog covers the top Java interview questions you should know and provides tips for answering them effectively. For a more interactive learning experience, check out this Java interview preparation video, which breaks down key concepts and interview strategies.

1. What is Java?

Answer: Java is a high-level, object-oriented programming language developed by Sun Microsystems (now owned by Oracle). It is designed to have as few implementation dependencies as possible, allowing developers to write code that runs on all platforms supporting Java without the need for recompilation.

Pro Tip: Mention the "write once, run anywhere" (WORA) principle during your interview to emphasize your understanding of Java’s cross-platform capabilities.

2. What is the Difference Between JDK, JRE, and JVM?

Answer:

JDK (Java Development Kit): Contains tools for developing Java applications, including the JRE and compilers.

JRE (Java Runtime Environment): A subset of JDK, containing libraries and components required to run Java applications.

JVM (Java Virtual Machine): The part of the JRE responsible for executing Java bytecode on different platforms.

Pro Tip: Explain how these components interact to demonstrate a deeper understanding of Java's execution process.

3. Explain OOP Principles in Java

Answer: Java is based on four main principles of Object-Oriented Programming (OOP):

Encapsulation: Bundling data and methods that operate on the data within one unit (class).

Inheritance: Creating a new class from an existing class to promote code reuse.

Polymorphism: The ability of a method or function to behave differently based on the object calling it.

Abstraction: Hiding complex implementation details and showing only the necessary features.

Pro Tip: Use a real-world example to illustrate these principles for better impact.

4. What are Constructors in Java?

Answer: Constructors are special methods used to initialize objects in Java. They have the same name as the class and do not have a return type. There are two types:

Default Constructor: Automatically created if no other constructors are defined.

Parameterized Constructor: Accepts arguments to initialize an object with specific values.

Pro Tip: Highlight the differences between constructors and regular methods, and explain constructor overloading.

5. What is the Difference Between == and .equals() in Java?

Answer:

==: Used to compare primitive data types or check if two object references point to the same memory location.

.equals(): Used to compare the content within objects. This method should be overridden for custom comparison logic in classes.

Pro Tip: Demonstrating this concept with code snippets can be a game-changer in your interview.

6. What are Java Collections?

Answer: The Java Collections Framework (JCF) provides a set of classes and interfaces to handle collections of objects. Commonly used collections include:

List (e.g., ArrayList, LinkedList)

Set (e.g., HashSet, TreeSet)

Map (e.g., HashMap, TreeMap)

Pro Tip: Be prepared to discuss the performance differences between various collections and when to use each.

7. What is Exception Handling in Java?

Answer: Exception handling in Java involves managing runtime errors to maintain normal program flow. The main keywords used are:

try: Block to wrap code that might throw an exception.

catch: Block to handle the exception.

finally: Block that always executes, used for cleanup code.

throw and throws: Used to manually throw an exception and indicate that a method may throw an exception, respectively.

Pro Tip: Discuss custom exceptions and when it is appropriate to create them for better code design.

8. What is Multithreading in Java?

Answer: Multithreading is a feature in Java that allows concurrent execution of two or more threads. It is useful for performing multiple tasks simultaneously within a program.

Pro Tip: Familiarize yourself with the Thread class and Runnable interface. Highlight synchronization and thread-safe practices to show advanced understanding.

9. What are Lambda Expressions in Java?

Answer: Introduced in Java 8, lambda expressions provide a concise way to implement functional interfaces. They enable writing cleaner, more readable code for single-method interfaces (e.g., using a lambda to sort a list).

Example:

java

Copy code

List<String> list = Arrays.asList("apple", "banana", "cherry");

list.sort((a, b) -> a.compareTo(b));

Pro Tip: Mention how lambda expressions contribute to functional programming in Java.

10. What is the Significance of the final Keyword?

Answer: The final keyword can be used with variables, methods, and classes to restrict their usage:

Variables: Makes the variable constant.

Methods: Prevents method overriding.

Classes: Prevents inheritance.

Pro Tip: Explain how using final can improve security and design integrity in your applications.

Conclusion

Reviewing these questions and understanding their answers can prepare you for technical interviews. For additional explanations and examples, check out this detailed Java interview preparation video.

youtube

#Youtube

0 notes

1stepgrow · 6 months ago

Text

This video will help you to understand what is Treemap and Gauge Chart in power bi, how to use Treemap and Gauge Chart, formatting Treemap and Gauge Chart for Power BI report.

#powerbi

0 notes

vatt-world · 6 months ago

Text

hi--

public class EmployeeStore { public static void main(String[] args) { // TreeMap with salary as the key and Employee as the value TreeMap employeeMap = new TreeMap<>(); // Adding employees to the TreeMap employeeMap.put(50000, new Employee("Alice", 50000)); employeeMap.put(70000, new Employee("Bob", 70000)); employeeMap.put(60000, new Employee("Charlie", 60000)); employeeMap.put(80000, new Employee("David", 80000)); // Displaying employees sorted by salary for (Map.Entry<Integer, Employee> entry : employeeMap.entrySet()) { System.out.println(entry.getValue()); } }

/// public class EmployeeStore { public static void main(String[] args) { // TreeMap with custom comparator to sort by salary, then by id TreeMap employeeMap = new TreeMap<>(); // Adding employees to the TreeMap employeeMap.put(new EmployeeKey(50000, 1), new Employee(1, "Alice", 50000)); employeeMap.put(new EmployeeKey(70000, 2), new Employee(2, "Bob", 70000)); employeeMap.put(new EmployeeKey(60000, 3), new Employee(3, "Charlie", 60000)); employeeMap.put(new EmployeeKey(50000, 4), new Employee(4, "David", 50000)); // Displaying employees sorted by salary, then by id for (Map.Entry<EmployeeKey, Employee> entry : employeeMap.entrySet()) { System.out.println(entry.getValue()); } }

}

// Helper class to represent a composite key of salary and id class EmployeeKey implements Comparable { private int salary; private int id;public EmployeeKey(int salary, int id) { this.salary = salary; this.id = id; } @Override public int compareTo(EmployeeKey other) { if (this.salary != other.salary) { return Integer.compare(this.salary, other.salary); } else { return Integer.compare(this.id, other.id); } }

}

///

public class EmployeeStreamExample { public static void main(String[] args) { // Creating a list of employees List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000)); employees.add(new Employee(2, "Bob", 70000)); employees.add(new Employee(3, "Charlie", 60000)); employees.add(new Employee(4, "David", 50000)); // Using Stream API to sort by salary, then by id if salaries are equal List<Employee> sortedEmployees = employees.stream() .sorted(Comparator.comparingInt(Employee::getSalary) .thenComparingInt(Employee::getId)) .collect(Collectors.toList()); // Displaying the sorted employees sortedEmployees.forEach(System.out::println); }

}

/// public class EmployeeStreamExample { public static void main(String[] args) { // Creating a list of employees List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000)); employees.add(new Employee(2, "Bob", 70000)); employees.add(new Employee(3, "Charlie", 60000)); employees.add(new Employee(4, "David", 50000)); // Getting an employee by id int searchId = 3; Optional<Employee> employee = employees.stream() .filter(e -> e.getId() == searchId) .findFirst(); // Checking if an employee was found and displaying the result if (employee.isPresent()) { System.out.println("Employee found: " + employee.get()); } else { System.out.println("Employee with id " + searchId + " not found."); } }

}

///

public class EmployeeStreamExample { public static void main(String[] args) { // Creating a list of employees List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000.0)); employees.add(new Employee(2, "Bob", 70000.0)); employees.add(new Employee(3, "Charlie", 60000.0)); employees.add(new Employee(4, "David", 50000.0)); // Converting to a Map with name as the key and salary as the value Map<String, Double> employeeSalaryMap = employees.stream() .collect(Collectors.toMap(Employee::getName, Employee::getSalary)); // Displaying the map employeeSalaryMap.forEach((name, salary) -> System.out.println("Name: " + name + ", Salary: " + salary)); }

}

/ Creating a list of employees List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000)); employees.add(new Employee(2, "Bob", 70000)); employees.add(new Employee(3, "Charlie", 60000)); employees.add(new Employee(4, "David", 50000)); // Using Stream API to sort by salary, then by id if salaries are equal List<Employee> sortedEmployees = employees.stream() .sorted(Comparator.comparingInt(Employee::getSalary) .thenComparingInt(Employee::getId)) .collect(Collectors.toList()); // Displaying the sorted employees sortedEmployees.forEach(System.out::println); }

//////

public static void main(String[] args) { // Creating a list of employees List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000)); employees.add(new Employee(2, "Bob", 70000)); employees.add(new Employee(3, "Charlie", 60000)); employees.add(new Employee(4, "David", 50000)); // Getting an employee by id int searchId = 3; Optional<Employee> employee = employees.stream() .filter(e -> e.getId() == searchId) .findFirst(); // Checking if an employee was found and displaying the result if (employee.isPresent()) { System.out.println("Employee found: " + employee.get()); } else { System.out.println("Employee with id " + searchId + " not found."); }

filter(e -> e.getId() == searchId) filters the stream to find employees with an id matching searchId. findFirst() returns an Optional, containing the first employee that matches the criteria, if any. ////////////////

List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000.0)); employees.add(new Employee(2, "Bob", 70000.0)); employees.add(new Employee(3, "Charlie", 60000.0)); employees.add(new Employee(4, "David", 50000.0)); // Converting to a Map with name as the key and salary as the value Map<String, Double> employeeSalaryMap = employees.stream() .collect(Collectors.toMap(Employee::getName, Employee::getSalary)); // Displaying the map employeeSalaryMap.forEach((name, salary) -> System.out.println("Name: " + name + ", Salary: " + salary)); }

employees.stream() creates a stream from the list of employees. collect(Collectors.toMap(Employee::getName, Employee::getSalary)) collects the stream into a Map where: Employee::getName is used as the key (employee’s name). Employee::getSalary is used as the value (employee’s salary). ////////////// If employee names are not unique, you can handle duplicates by specifying a merge function when using Collectors.toMap

List employees = new ArrayList<>(); employees.add(new Employee(1, "Alice", 50000.0)); employees.add(new Employee(2, "Bob", 70000.0)); employees.add(new Employee(3, "Charlie", 60000.0)); employees.add(new Employee(4, "Alice", 55000.0)); // Duplicate name "Alice" with different salary // Converting to a Map with name as the key and salary as the value, keeping the higher salary for duplicates Map<String, Double> employeeSalaryMap = employees.stream() .collect(Collectors.toMap( Employee::getName, Employee::getSalary, Double::max // Merge function to keep the higher salary for duplicate names )); // Displaying the map employeeSalaryMap.forEach((name, salary) -> System.out.println("Name: " + name + ", Salary: " + salary)); }

Merge Function: In Collectors.toMap, the third argument is a merge function (Double::max), which is used to resolve duplicate keys (in this case, duplicate employee names). Double::max ensures that if two employees have the same name, the one with the higher salary is kept. Alternatively, you could use Double::min to keep the lower salary or (s1, s2) -> s1 + s2 to sum the salaries. //////////////

Spring Boot 3 Java 17 as the Minimum Requirement:

Spring Boot 3 requires Java 17 or later, taking advantage of new language features and performance improvements available in recent Java versions. Native Image Support with GraalVM: //////////////

Spring Data JPA is a part of the Spring Data framework that simplifies the implementation of JPA (Java Persistence API) repositories. It provides abstractions over JPA and simplifies the database access layer, making it easier to perform CRUD operations, pagination, sorting, and more without writing boilerplate code.

//////////////

public interface EmployeeRepository extends JpaRepository { List findByName(String name); // Derived query@Query("SELECT e FROM Employee e WHERE e.salary > :salary") List<Employee> findEmployeesWithSalaryGreaterThan(@Param("salary") double salary);

}

findByName(String name): Spring Data JPA automatically interprets this method name and generates the query to find employees by name. findEmployeesWithSalaryGreaterThan(double salary): This custom query uses the @Query annotation with JPQL (Java Persistence Query Language) to find employees with a salary greater than a specified amount.

……..

It defines annotations (like @Entity, @Table, @Id, etc.) and APIs (like EntityManager) for managing the lifecycle of entities and querying the database. ////

o find the employee with the maximum salary in a Spring Data JPA repository, you have several options. Here’s how to do it using different approaches.

@Query("SELECT e FROM Employee e WHERE e.salary = (SELECT MAX(e2.salary) FROM Employee e2)") Optional findEmployeeWithMaxSalary();

//////

public interface EmployeeRepository extends JpaRepository { Optional findTopByOrderBySalaryDesc(); } …………

public Optional getEmployeeWithMaxSalary() { return employeeRepository.findAll() .stream() .max(Comparator.comparingDouble(Employee::getSalary)); } ………………

public interface EmployeeRepository extends JpaRepository {@Query("SELECT e FROM Employee e WHERE e.salary > :salary") List<Employee> findEmployeesWithSalaryGreaterThan(@Param("salary") double salary);

} …………………. ublic interface EmployeeRepository extends JpaRepository {@Query("SELECT e.id FROM Employee e WHERE e.salary > :salary") List<Long> findEmployeeIdsWithSalaryGreaterThan(@Param("salary") double salary);

}

/////////////////

public interface EmployeeRepository extends JpaRepository {@Query("SELECT e.id AS id, e.name AS name FROM Employee e WHERE e.salary > :salary") List<EmployeeIdNameProjection> findEmployeeIdAndNameWithSalaryGreaterThan(@Param("salary") double salary);

}

///////////////// Ensure @SpringBootApplication is on the Main Class The @SpringBootApplication annotation is crucial, as it enables component scanning, autoconfiguration, and configuration properties. Make sure it’s present on your main class:

@Query("SELECT new com.example.demo.EmployeeIdName(e.id, e.name) FROM Employee e WHERE e.salary > :salary") List findEmployeeIdAndNameWith

//………….

Annotate Classes with @Component, @Service, @Repository, etc. Spring Boot requires beans to be annotated with @Component or a stereotype annotation like @Service, @Repository, or @Controller so that they’re detected by component scanning. Ensure your classes are annotated properly:

//………….

In Maven, a BOM (Bill of Materials) is a special type of dependency that manages dependency versions across multiple modules or dependencies. It’s commonly used to ensure consistent versions of libraries, especially in Spring Boot projects. The BOM prevents version conflicts by specifying a set of compatible dependencies.

//…………. How Works Centralized Version Control: You declare versions of dependencies in the parent POM without specifying them in the child POMs. Inheritance: Child POMs inherit these dependencies and can add them without specifying the version, as the version is inherited from in the parent POM. Scope Control: You can set the scope for dependencies centrally, and child modules will use these settings.

//…………. Singleton: Ensures a class has only one instance and provides a global point of access to it. Useful for resources like databases, configuration managers, and logging.

Factory Method: Provides an interface for creating objects but allows subclasses to alter the type of objects created. Useful when the exact type of object isn’t known until runtime.

Facade: Provides a simplified interface to a complex subsystem, making it easier to use.

Flyweight: Shares objects to support large numbers of fine-grained objects efficiently. Useful for objects that are costly to create.

Proxy: Provides a surrogate or placeholder to control access to another object, useful for lazy initialization, access control, logging, etc.

State: Allows an object to alter its behavior when its internal state changes, appearing to change its class.

Strategy: Defines a family of algorithms and makes them interchangeable, allowing the algorithm to vary independently from the clients.''

////////////

Singleton Pattern Usage in Spring: By default, Spring beans are singletons. This means a single instance of each bean is created and shared across the application context.

Purpose: Ensures that only one instance of a bean is created per Spring container, promoting memory efficiency and shared resource usage. ……………

Factory Method Pattern Usage in Spring: Spring uses the Factory Method pattern to create bean instances. The BeanFactory and ApplicationContext containers in Spring serve as factories for creating and managing beans.

Example: The FactoryBean interface allows you to define a factory for creating specific bean instances. ……………….. Dependency Injection (DI) / Inversion of Control (IoC) Usage in Spring: Dependency Injection is a fundamental pattern in Spring, where the framework manages the dependencies of objects rather than the objects creating their own dependencies.

Example: Using @Autowired or constructor injection to inject dependencies …………………….

Spring provides several other scopes for beans:

Prototype: A new instance is created every time the bean is requested.

java Copy code @Scope("prototype") @Component public class MyPrototypeService { } Request (Web Application): A new bean instance is created for each HTTP request.

java Copy code @Scope("request") @Component public class MyRequestScopedService { } Session (Web Application): A new bean instance is created for each HTTP session.

java Copy code @Scope("session") @Component public class MySessionScopedService { } Application (Web Application): A single instance is created for the lifecycle of the ServletContext.

////////////////////////////

How to Specify Bean Scope To specify a different scope for a bean, use the @Scope annotation along with @Component, @Service, @Repository, or @Controller:

java Copy code import org.springframework.context.annotation.Scope; import org.springframework.stereotype.Service;

@Service @Scope("prototype") // Change scope to prototype public class MyService {

///////////

microservices architecture, managing session scope across distributed services requires a different approach from traditional monolithic applications. Since each microservice is independently deployed and has its own memory space, session data cannot be stored in the memory of a single service instance. Here are some best practices and solutions for managing session scope in a microservices environment:

Stateless Microservices with Token-Based Authentication The recommended approach in a microservices architecture is to make services stateless, meaning each request should contain all the information required to process it, and no session data should be stored on the server.

JWT (JSON Web Tokens): Instead of storing session data on the server, you can use JWTs to encode user information. The token is then passed along with each request, allowing the microservices to authenticate and authorize the user without storing session data. OAuth2/OpenID Connect: Use OAuth2 or OpenID Connect with a central identity provider (such as Keycloak, Okta, or Auth0) for managing authentication and authorization. These protocols often use access tokens or ID tokens that services can verify without storing session data.

/////////////////

Spring Session for Distributed Session Management Spring Session is a project that provides support for managing session data in a distributed environment, such as Redis, JDBC, or Hazelcast. It decouples session management from the container (e.g., Tomcat) and centralizes it in a shared data store.

Example of Spring Session with Redis:

Add Dependencies: Add the Spring Session and Redis dependencies in your pom.xml.

////////////

Open/Closed Principle (OCP) Definition: Software entities (classes, modules, functions) should be open for extension but closed for modification.

Explanation: You should be able to add new functionality to a class without modifying its existing code. This is typically achieved using inheritance, interfaces, or polymorphism.

Single Responsibility Principle: Each class should have one responsibility. Open/Closed Principle: Classes should be open to extension but closed to modification. Liskov Substitution Principle: Subclasses should be replaceable for their base classes. Interface Segregation Principle: Avoid forcing clients to implement interfaces they don’t use. Dependency Inversion Principle: Depend on abstractions, not on conc

In a microservices architecture, managing session scope across distributed services requires a different approach from traditional monolithic applications. Since each microservice is independently deployed and has its own memory space, session data cannot be stored in the memory of a single service instance. Here are some best practices and solutions for managing session scope in a microservices environment:

OAuth2/OpenID Connect: Use OAuth2 or OpenID Connect with a central identity provider (such as Keycloak, Okta, or Auth0) for managing authentication and authorization. These protocols often use access tokens or ID tokens that services can verify without storing session data.

0 notes