what type of program can you use to enter your java program?

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Last Updated on 11 March 2020   | Print Email

If you are new to Java programming and wish to acquire it right now past doing some hands-on practice, you have come to the right place. This tutorial will help yous writing your start Java program, typically a "hello world" one - your first pace of the adventure into Java programming world. Throughout this tutorial, you will larn central concepts and steps which are necessary for every Coffee fresher.

To start, all you need is a fresh computer without whatsoever Java software installed, a text-based editor and a good internet connection.

NOTES: This beginner tutorial is targeted for Windows environment.

ane. Download and install Java Development Kit

In social club to write and run a Coffee program, y'all demand to install a software program called Java SE Development Kit (or JDK for short, and SE means Standard Edition). Basically, a JDK contains:

• • JRE (Java Runtime Surround): is the cadre of the Java platform that enables running Coffee programs on your computer. The JRE includes JVM (Java Virtual Machine) that runs Coffee programs by translating from bytecode to platform-dependent code and executes them (Java programs are compiled into an intermediate form chosen bytecode), and other cadre libraries such as collections, File I/O, networking, etc.
  • Tools and libraries that support Java evolution.

The JDK ships with 2 powerful tools which every Java developer should be familiar with:

• • javac.exe: is Java compiler that translates programs written in Java code into bytecode form.
  • java.exe: is the Coffee Virtual Machine launcher that executes bytecode.

Click this link to download the latest version of JDK installer program:

Check the choice "Accept License Agreement", and choose an appropriate version for your calculator from the listing. Here we choose the version for Windows x64:

After downloading the program, run it to install the JDK on your computer (just post-obit the steps, exit the defaults and click Next, Next…):

You would encounter the JDK is installed in the following directory, for example: C:\Programme Files\Java\jdk1.7.0_21. The post-obit screenshot describes the JDK'due south directory structure:

Now let's test if Java runtime is installed correctly. Open up a command prompt window and type:

java -version

You would encounter the following event:

That shows version of the JRE, e.g. "1.7.0_21" - Congratulations! Your reckoner is now capable of running Java programs.

Now try to type the following command:

javac -version

You would see the post-obit error:

That's because Windows could not find the javacplan, and so we need to set up some environment variables which tell the location of javac.exe.

two. Set up up environment variables

At present we're going to set environment variables so that the javac.exeprogramme can exist accessed anywhere from command line. On Windows vii, go to My Computer and click System Properties:

Then click Advanced organization settings:

The Organization Properties dialog appears, select Advanced tab and click Environment Variables...:

The Environment Variable dialog appears, click on the New… button under the System variables section.

That opens up the New System Variable dialog. Type the post-obit information:

The field Variable proper name must exist JAVA_HOME, and the field Variable value must point to JDK'due south installation directory on your computer. Hither information technology is set to c:\Program Files\Java\jdk1.7.0_21. Click OK to close this dialog.

Now dorsum to the Surround Variables dialog, look for a variable called Path under the System Variables list, and click Edit…:

In the Edit Arrangement Variable dialog, suspend the following to the end of the field Variable value:

;%JAVA_HOME%\bin

Note that there is a semicolon at the first to separate this value from other ones. Click OK 3 times to close all the dialogs.

Now we accept to quit the current command prompt and open up a new one to run across the changes takes effect. Blazon the post-obit command over again in the re-opened control prompt window:

javac -version

Yous would see the following output:

Congratulations! You lot accept completed the setup for essential Coffee development environment on your reckoner. It'southward now set to write your outset Java plan.

3. Code a Coffee hello world program

Open up a simple text editor plan such as Notepad and blazon the following content:

public form HelloWorld { 	public static void main(String[] args) { 		System.out.println("Howdy globe!"); 	} }

Save the file equally HelloWorld.coffee (note that the extension is .java ) under a directory, let'southward say, C:\Java.

Don't worry if you don't understand everything in this uncomplicated Java code. The following film explains it nicely:

Every Java program starts from the main() method. This program simply prints "Hello world" to screen.

4. Compile your beginning Coffee programme

Now let'southward compile our first plan in the HelloWorld.coffee file using javac tool. Type the following control to change the electric current directory to the i where the source file is stored:

cd C:\Coffee

And blazon the following command:

javac HelloWorld.coffee

That invokes the Java compiler to compile code in the HelloWorld.java file into bytecode. Note that the file name ends with .java extension. You lot would see the post-obit output:

If everything is fine (e.g. no error), the Java compiler quits silently, no fuss. After compiling, it generates the HelloWorld.grade file which is bytecode form of the HelloWorld.java file. Now try to blazon dir in the command line, we'll come across the .course file:

So remember a Java program volition exist compiled into bytecode form (.class file).

five. Run your first Java program

It'due south now ready to run our first Coffee program. Blazon the following command:

java HelloWorld

That invokes the Coffee Virtual Automobile to run the program called HelloWorld (note that there is no .coffee or .class extension). You lot would see the post-obit output:

Information technology just prints out "Howdy earth!" to the screen and quits. Congratulations! You take successfully run your outset Java programme!

six. What nosotros have learnt so far

Throughout this tutorial you accept learnt the post-obit things:

• • JDK is the Java SE Evolution Kit that contains tools and libraries for Java development.
  • JRE is the Java Runtime Environment that enables running Java programs on your reckoner.
  • JVM is the Coffee Virtual Machine that actually executes Coffee programs. With JVM, programs written in Coffee can run on multi-platforms (thus Java is called cross-platform language).
  • How to install JDK and configure environment variables.
  • javac is the Java compiler. It translates Java source lawmaking into bytecode.
  • java is the JVM launcher which we employ to run our program.
  • Every Java program starts from the main() method.
  • When compiling, the compiler generates a .class file from a .coffee file.

Yous can besides watch the video version of this tutorial:

Next, I recommend you to read this commodity: Sympathise Classes and Objects in Java

Related Coffee How-do-you-do World Tutorials:

• How to compile, package and run a Coffee program using command-line tools (javac, jar and java)
• Coffee Hello World for Beginner with NetBeans IDE
• How to create, build and run a Java Hello World programme with Eclipse
• How to Compile and Run a Java Program with TextPad
• How to compile and run a Java program with Sublime Text 3

Near the Author:

Nam Ha Minh is certified Java developer (SCJP and SCWCD). He started programming with Java in the time of Java 1.iv and has been falling in dearest with Java since and so. Make friend with him on Facebook and watch his Coffee videos you YouTube.

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Source: https://www.codejava.net/java-core/how-to-write-compile-and-run-a-hello-world-java-program-for-beginners

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