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Compile And Run Java Programs | 2021 Guide

This simple basic tutorial will guide you to compile and run Java programs effortlessly. I created this post for the complete Java beginners.

I hope you have understood how to write a Java program from the previous guide. If you haven’t read the previous guide, I strongly suggest you read it first and then come back. If you have already written your Java program, then let’s not wait anymore to see the Java program in action.

After completing this guide, you will learn how to compile and run Java programs successfully using an IDE and a Text Editor.

So, with no further delay, let get right into the topic.

Previous Topic: Write Your First Java Program

Next Topic: Java Variables

Page Contents

Write Using a Text Editor

If you use a text editor, then things are easier than you think. You open the text editor and type the Java program given above and save the file in a directory you would like.

You need to use the Command Window/Terminal to run the Java program. Use the following steps to compile and run Java programs successfully.

    • Open the text editor
    • Type the Java program
    • Save the program
    • Go to the saved program directory
    • If you are using the Windows operating system, click on the address bar and type ‘cmd‘, then press the enter key to open the command prompt in the same directory
    • If you are using a Linux based OS, right-click anywhere on the directory window and select ‘open in terminal
  • Enter the command ‘javac<space> Filename.java‘ to compile the Java program. Then the compiler will generate the byte code file in the ‘ClassName.class‘ format.
  • Enter the command ‘java<space>ClassName‘ to run the program.

The javac Command

The javac command compiles the Java source code and creates the byte code.

The java Command

The java command loads the byte code and starts the java runtime environment to run the Java program.

It will display the output in the command window as you see below.

 

Write Using The Eclipse IDE

Follow the below steps to create, compile and run Java programs using Eclipse IDE.

1. Download and install the Eclipse IDE from the official Eclipse website here.

Note: You must install JDK and set up the Java environment before this step.

The eclipse setup wizard will pick the installed JDK automatically. You can install the ‘Eclipse IDE for Java Developers‘ for now.

Here I use the Eclipse 2020-09 version. It requires the JDK 11 or higher version.

2. Open the Eclipse IDE.

Use any of the following ways to open the Eclipse IDE.

  • Click on the Launch button after the installation.
  • Open it using the desktop shortcut
  • Go to the installed folder and double click on the ‘eclipse.exe‘ file.

3. Choose a workspace for your projects.

4. Create a Java project

Use the following steps to create a Java project.

  • Select File -> New -> Java Project
  • Enter the project name
  • Choose the project location or continue with the default location
  • Choose an execution environment JRE from the drop-down box under the JRE section and click on the Next button
  • Click on the Finish button

5. Create a package for your Java program. To create the package, expand the created project on the ‘Package Explorer‘ on the top left corner.

Right-click on the source (src) folder. Choose New -> Package. Enter the package name and click Finish.

Note: The package name must be in lowercase letters. It must not include spaces, and it should not start with a digit.

6. Create Your Java class

  • Right-click on the package you have created
  • Select New -> Class
  • Enter the class name
  • Click on Finish

Note: There is an option to add the main method automatically in the ‘Create a New Java Class‘ window. You can choose that if you wish.

After clicking on the Finish button, your Java program will be open in the Eclipse source code editor.

 

7. Enter the code in your Java program (You can refer to the sample program given in the previous guide here). Press ctrl+S to save the program.

8. Run the Java program. Use any of the following ways to run your Java program.

  • Click on ‘Run‘ on the top menu bar or press ctrl+F11

 

  • Right-click on your program and select Run As -> Java Application or click anywhere on your program and enter alt+shift+X then press J

 

  • Click on the ‘play button’ under the top menu bar and select your program or select Run As -> Java Application

 

It will print the output in the console as you can see below.

 

This is how you can compile and run Java programs using text editors and Eclipse IDE. I hope you find this helpful.

Now It is Your Turn

In this guide, I explain the small simple steps to compile and run Java programs.

So, would you like to use a text editor or an IDE to compile and run your Java program?

Let me know by dropping a quick comment.!

If you find this guide useful, share this with your friends. Spread the knowledge as much as you can.!

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