#current date using localdatetime

[holytheoristtastemaker]

When you develop some software you may not think about timezones at first. Unless you live in a country which has to deal with multiple time zones, such as the United States or Russia. I recently came across an issue involving timezones. There were some unit tests making assertions about dates that used to work at my office in France but weren't working in Morocco for new members on our team. Here is the unit test working in France but not in Morocco ‌This was an opportunity for me to learn how to correctly handle dates and times for international software. In this article, I’ll introduce time zone issues and share some rules to follow. Quick introduction to time zones As the earth is kind of a sphere, the sun is rising in Japan while it's setting in America. If everyone used global time, let’s say 09:00 would be sunrise in Japan, but for Americans it would be sunset. Not very handy. To make sure the time is coordinated with the sun for everyone, it’s necessary to shift from global time according to your location. As a result, the globe gets split into time zones and each gets an offset. This offset is a number of minutes to add to the global time to get your time zone time. It can be either positive or negative. Standard world time zones — Illustration by Hellerick from Wikimedia Commons Global time is called UTC, it stands for Coordinated Universal Time. You may also heard about GMT which is a time zone without any offset. For instance, when it’s 10:50 at UTC, it’s also  03:50 in San Francisco with a -0700 offset and 18:50 in Beijing with a +0800 offset. Yet, the shift isn’t only in whole hours: Nepal's offset is +0545. You can check it out on Wikipedia. In addition of this offset, which comes with the time zone, some countries also shift clocks twice a year. DST or summer time adds one hour to the time zone offset before summer. Then, the clock is reset to the time zone time in winter. The goal is to make the daytime longer. The most common way to figure out a time zone is by using the IANA Time Zone Database. You end up with a string such as Europe/Paris following the Area/City pattern. Besides, Microsoft maintains its own Microsoft Time Zone Database used on its operating systems. But this can cause issues when running cross-platform .NET Core apps. IANA is still the go-to. The Microsoft database isn't updated often, it contains less history, fairly curious time zone names (eg: Romantic Standard Time) and is error prone. For example, try to not mix up Arab , Arabic and Arabian Standard Time. For more details on each database and their differences, check out this article. One last thing: there are plenty of ways to write a date. Fortunately, the ISO 8601 specification sets a common rule for date formatting. November 11, 2018 at 12:51:43 AM (in a time zone at UTC+00:00) 2018-11-05T12:51:43Z

http://damianfallon.blogspot.com/2020/04/how-to-handle-timezones-and-synchronize_63.html

[tutorialspointexamples]

Java executor

Interfaces. Executor is a simple standardized interface for defining custom thread-like subsystems, including thread pools, asynchronous I/O, and lightweight task frameworks. Depending on which concrete Executor class is being used, tasks may execute in a newly created thread, an existing task-execution thread, or the thread calling execute, and may execute sequentially or concurrently. ExecutorService provides a more complete asynchronous task execution framework. An ExecutorService manages queuing and scheduling of tasks, and allows controlled shutdown. The ScheduledExecutorService subinterface and associated interfaces add support for delayed and periodic task execution. ExecutorServices provide methods arranging asynchronous execution of any function expressed as Callable, the result-bearing analog of Runnable. A Future returns the results of a function, allows determination of whether execution has completed, and provides a means to cancel execution. A RunnableFuture is a Future that possesses a run method that upon execution, sets its results. How to get sublist from arraylist in java? How to sort arraylist using comparator in java? How to reverse contents of arraylist java? How to shuffle elements in an arraylist in java? How to swap two elements in an arraylist java? how to read all elements in linkedlist by using iterator in java? How to copy or clone linked list in java? How to add all elements of a list to linkedlist in java? How to remove all elements from a linked list java? How to convert linked list to array in java? How to sort linkedlist using comparator in java? How to reverse linked list in java? How to shuffle elements in linked list in java? How to swap two elements in a linked list java? How to add an element at first and last position of linked list? How to get first element in linked list in java? How to get last element in linked list in java? How to iterate through linked list in reverse order? 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Numeric literals with underscore. Java catch multiple exceptions.

[t-baba]

Arrow for Better Date and Time in Python

Manipulating date and time is a common scenario in any programming language. Without the help of a handy library, it can become a tedious job requiring sufficient effort. Let's have a look at the Arrow library, which is heavily inspired by popularly used Python libraries Moment.js and Requests. Arrow provides a friendly approach for handling date and time manipulation, creation, etc. 

From the official documentation:

Arrow is a Python library that offers a sensible, human-friendly approach to creating, manipulating, formatting and converting dates, times, and timestamps. It implements and updates the datetime type, plugging gaps in functionality, and provides an intelligent module API that supports many common creation scenarios.

Getting Started With Arrow

To get started with the Arrow library, you need to have Python installed on your system. Also make sure you have pip, Python package manager, installed in your environment.

Now install Arrow using pip.

pip install arrow

You'll learn how to use Arrow in your web application development project for date and time manipulation, creation, etc. So let's start by creating a web application using Python Flask.

Using pip, install Python Flask, if it's not already installed.

pip install Flask

Create a file called app.py which would be the Python application file. Add the following code to app.py:

from flask import Flask app = Flask(__name__) @app.route("/") def hello(): return "Welcome to Arrow Library" if __name__ == '__main__': app.run()

Save the above changes and run the application using python app.py, and you should have the application running on http://localhost:5000/.

Local Time to UTC Time & Vice Versa

One of the most common scenarios that you face in a web application development project is fetching the local time, converting the local time to UTC (Coordinated Universal Time) time and then converting UTC time to local time for display in a web application based on time zone. 

To use Arrow in your Python Flask project, you need to import the library in app.py.

import arrow

Once it's imported, you can straight away use the arrow object for date and time manipulation and creation.

Let's create a route and method to fetch the local time. Add a route called getLocalTime and its corresponding method. Arrow provides a method called now to get the current local time. Use the now method to get the local time, and to return the date you need to convert it into ISO format. Here is how the code looks:

@app.route("/getLocalTime") def getLocalTime(): local = arrow.now() return local.isoformat()

Save the above changes and restart the server. Point your browser to http://localhost:5000/getLocalTime and you should be able to view the local time.

Normally, you tend to save the date and time in UTC format in databases and display the local time by converting the UTC time to local time. So let's have a look at how to convert the local time to UTC time for database storage. 

Create a route and method called getCurrentUtcTime. In order to get the current UTC time, arrow provides a method called utcnow. You can use it to get the current UTC time as shown:

@app.route("/getCurrentUtcTime") def getCurrentUtcTime(): utc = arrow.utcnow() return utc.isoformat()

The above method gets the current UTC time. If you already have a date and time for which you want to get the UTC, arrow provides a to method for doing this. Using the to method, you need to provide the time zone to which you need the date and time to be converted. So, here is how you can convert the local time to UTC:

@app.route("/getUtcTime") def getUtcTime(): local = arrow.now() utc = local.to('utc') return utc.isoformat()

When you save the date and time in the database, you save it as a timestamp. To get the UTC timestamp, you need to call the .timestamp attribute of the object.

arrow.now().timestamp

You cannot show the UTC timestamp when displaying data to the client side. You need to convert the UTC timestamp to local time. In order to do that, you first need to create the arrow object using the arrow.get method. Then you can use the arrow.to method to convert the UTC time to local time. Here is how the code looks:

@app.route("/convertUtcToLocal") def convertUtcToLocal(): local = arrow.now() utcTimeStamp = local.to('utc').timestamp localDateObj = arrow.get(utcTimeStamp).to('local') return localDateObj.isoformat()

Save the above changes and restart the server. Point your browser to http://localhost:5000/convertUtcToLocal and you should be able to view local time retrieved by converting the UTC timestamp to local time.

Manipulating Date & Time

Most of the time, it's required to manipulate the date and time by adding or removing a few hours, minutes, etc. to the datetime object. Arrow provides two methods called replace and shift for manipulating the datetime object.

Let's say that you have an arrow datetime object. Now you want to replace a few things in the datetime object. You want to alter the minute and second of the datetime.

>>> localDateTime = arrow.now() >>> localDateTime <Arrow [2017-09-29T07:39:29.237652+05:30]>

To replace the minute and second of the localDateTime, you can use the replace method provided by the arrow library. Here is how the syntax looks:

>>> localDateTime.replace(minute = 01,second = 01) <Arrow [2017-09-29T07:01:01.237652+05:30]>

If you want to increment the datetime by a certain parameter like day, hour, week, etc., you can use the shift method. All you need to do is provide the parameter using which you need to shift the datetime. Let's say you need to increment the datetime by one day. The code would be like this:

>>> localDateTime = arrow.now() >>> localDateTime <Arrow [2017-09-29T08:03:57.806785+05:30]> >>> localDateTime.shift(days = +1) <Arrow [2017-09-30T08:03:57.806785+05:30]>

To decrement the datetime by two days, the code would be like:

>>> localDateTime.shift(days = -2) <Arrow [2017-09-27T08:03:57.806785+05:30]>

Formatting the Date Using Arrow

In order to format the datetime as per your custom format, you can use the format method provided by arrow. 

For example, to format datetime to YYYY-MM-DD format, you need to use the following code:

>>> localDateTime = arrow.now() >>> localDateTime <Arrow [2017-09-29T08:32:28.309863+05:30]> >>> localDateTime.format('YYYY-MM-DD') u'2017-09-29'

Similarly, to format datetime to YYYY-MM-DD HH:mm:ss format, you need to use the following code:

>>> localDateTime <Arrow [2017-09-29T08:32:28.309863+05:30]> >>> localDateTime.format('YYYY-MM-DD HH:mm:ss') u'2017-09-29 08:32:28'

Human-Friendly DateTime Representation

Arrow provides a method called humanize to represent the datetime in a human-friendly representation. Most of the time, the user needs to know how much time it has been since a particular time. You can use the humanize method to show the user how much time it has been since now. Here is some example code:

>>> currentDate = arrow.now() >>> currentDate <Arrow [2017-09-29T22:05:26.940228+05:30]> >>> currentDate.humanize() u'just now'

As seen in the above code, if you use humanize to represent how much time it has been since the current datetime, it would show the above result.

Now let's take a look at a prior date.

>>> earlierDate = arrow.now().shift(days=-3) >>> earlierDate <Arrow [2017-09-26T22:07:39.610546+05:30]> >>> earlierDate.humanize() u'3 days ago'

As seen in the above code, you just used the humanize method with an earlier date, and it shows the relative number of days with respective to the current date.

You can also use humanize to show the relative number of days between two dates. For example:

>>> laterDate = arrow.now().shift(days=+3) >>> laterDate <Arrow [2017-10-02T22:10:58.505234+05:30]> >>> earlierDate = arrow.now().shift(days=-3) >>> earlierDate <Arrow [2017-09-26T22:11:11.927570+05:30]> >>> earlierDate.humanize(laterDate) u'5 days ago'

As seen in the above example, you created a later date and an earlier date by shifting the number of days. Then you checked the relative number of days from earlierDate to laterDate using the humanize method, which printed the above message.

Converting to a Different Time Zone

Arrow provides a convert method to convert the local time to a preferred time zone. For example to convert the local time to UTC time, you can use the following command:

>>> arrow.now().to('utc') <Arrow [2017-09-30T16:58:45.630252+00:00]>

To convert the UTC time back to the local time zone, you can use the following code:

>>> utcTime = arrow.now().to('utc') >>> utcTime <Arrow [2017-09-30T17:01:30.673791+00:00]> >>> utcTime.to('local') <Arrow [2017-09-30T22:31:30.673791+05:30]>

To convert the UTC time to any specific time zone, you can specify the time zone and you'll get the time from that particular time zone. For example:

>>> utcTime.to('America/New_York') <Arrow [2017-09-30T13:01:30.673791-04:00]>

In the above code, you specified the UTC time to be converted to the America/New_York time zone, and similarly you can provide any time zone that you want the UTC to be converted to.

Wrapping It Up

In this tutorial, you saw how to use Arrow, a Python library for date and time manipulation, creation and formatting. From a developer point of view, the Arrow library seems to be a complete fit for date and time manipulations when used in a Python project.

Additionally, don’t hesitate to see what we have available for sale and for study in Envato Market, and don't hesitate to ask any questions and provide your valuable feedback using the feed below.

Do you have any prior experience using the Arrow library? What is your point of view? Did you face any issues while using the library? Do let us know your thoughts and suggestions in the comments below. 

by Roy Agasthyan via Envato Tuts+ Code http://ift.tt/2A70n3b

[topjavatutorial-blog]

How to get current date time (today's date) in Java

How to get current date time (today’s date) in Java

In this article, we will discuss how to get current date and time using the legacy Date and Calendar apis alongwith the Java 8 LocalDate, LocalTime, LocalDateTime and ZonedDateTime apis. Current date using java.util.Date instance Date d1 = new Date(); System.out.println(d1); // Tue Mar 06 22:50:37 EST 2018 If you are looking to format the current date in a specific format, use the…

[holytheoristtastemaker]

When you develop some software you may not think about timezones at first. Unless you live in a country which has to deal with multiple time zones, such as the United States or Russia. I recently came across an issue involving timezones. There were some unit tests making assertions about dates that used to work at my office in France but weren't working in Morocco for new members on our team. Here is the unit test working in France but not in Morocco ‌This was an opportunity for me to learn how to correctly handle dates and times for international software. In this article, I’ll introduce time zone issues and share some rules to follow. Quick introduction to time zones As the earth is kind of a sphere, the sun is rising in Japan while it's setting in America. If everyone used global time, let’s say 09:00 would be sunrise in Japan, but for Americans it would be sunset. Not very handy. To make sure the time is coordinated with the sun for everyone, it’s necessary to shift from global time according to your location. As a result, the globe gets split into time zones and each gets an offset. This offset is a number of minutes to add to the global time to get your time zone time. It can be either positive or negative. Standard world time zones — Illustration by Hellerick from Wikimedia Commons Global time is called UTC, it stands for Coordinated Universal Time. You may also heard about GMT which is a time zone without any offset. For instance, when it’s 10:50 at UTC, it’s also  03:50 in San Francisco with a -0700 offset and 18:50 in Beijing with a +0800 offset. Yet, the shift isn’t only in whole hours: Nepal's offset is +0545. You can check it out on Wikipedia. In addition of this offset, which comes with the time zone, some countries also shift clocks twice a year. DST or summer time adds one hour to the time zone offset before summer. Then, the clock is reset to the time zone time in winter. The goal is to make the daytime longer. The most common way to figure out a time zone is by using the IANA Time Zone Database. You end up with a string such as Europe/Paris following the Area/City pattern. Besides, Microsoft maintains its own Microsoft Time Zone Database used on its operating systems. But this can cause issues when running cross-platform .NET Core apps. IANA is still the go-to. The Microsoft database isn't updated often, it contains less history, fairly curious time zone names (eg: Romantic Standard Time) and is error prone. For example, try to not mix up Arab , Arabic and Arabian Standard Time. For more details on each database and their differences, check out this article. One last thing: there are plenty of ways to write a date. Fortunately, the ISO 8601 specification sets a common rule for date formatting. November 11, 2018 at 12:51:43 AM (in a time zone at UTC+00:00) 2018-11-05T12:51:43Z

http://damianfallon.blogspot.com/2020/04/how-to-handle-timezones-and-synchronize_7.html

[holytheoristtastemaker]

When you develop some software you may not think about timezones at first. Unless you live in a country which has to deal with multiple time zones, such as the United States or Russia. I recently came across an issue involving timezones. There were some unit tests making assertions about dates that used to work at my office in France but weren't working in Morocco for new members on our team. Here is the unit test working in France but not in Morocco ‌This was an opportunity for me to learn how to correctly handle dates and times for international software. In this article, I’ll introduce time zone issues and share some rules to follow. Quick introduction to time zones As the earth is kind of a sphere, the sun is rising in Japan while it's setting in America. If everyone used global time, let’s say 09:00 would be sunrise in Japan, but for Americans it would be sunset. Not very handy. To make sure the time is coordinated with the sun for everyone, it’s necessary to shift from global time according to your location. As a result, the globe gets split into time zones and each gets an offset. This offset is a number of minutes to add to the global time to get your time zone time. It can be either positive or negative. Standard world time zones — Illustration by Hellerick from Wikimedia Commons Global time is called UTC, it stands for Coordinated Universal Time. You may also heard about GMT which is a time zone without any offset. For instance, when it’s 10:50 at UTC, it’s also  03:50 in San Francisco with a -0700 offset and 18:50 in Beijing with a +0800 offset. Yet, the shift isn’t only in whole hours: Nepal's offset is +0545. You can check it out on Wikipedia. In addition of this offset, which comes with the time zone, some countries also shift clocks twice a year. DST or summer time adds one hour to the time zone offset before summer. Then, the clock is reset to the time zone time in winter. The goal is to make the daytime longer. The most common way to figure out a time zone is by using the IANA Time Zone Database. You end up with a string such as Europe/Paris following the Area/City pattern. Besides, Microsoft maintains its own Microsoft Time Zone Database used on its operating systems. But this can cause issues when running cross-platform .NET Core apps. IANA is still the go-to. The Microsoft database isn't updated often, it contains less history, fairly curious time zone names (eg: Romantic Standard Time) and is error prone. For example, try to not mix up Arab , Arabic and Arabian Standard Time. For more details on each database and their differences, check out this article. One last thing: there are plenty of ways to write a date. Fortunately, the ISO 8601 specification sets a common rule for date formatting. November 11, 2018 at 12:51:43 AM (in a time zone at UTC+00:00) 2018-11-05T12:51:43Z

http://damianfallon.blogspot.com/2020/04/how-to-handle-timezones-and-synchronize.html