A Complete Guide - Setting up Java Environment JDK, JRE

For Linux:

1. Download the JDK:

   • If using a web browser, you can download directly. For automated downloads, you might use wget:

     wget 

2. Extract the Archive:

   • Open Terminal.
   • Navigate to the directory containing the .tar.gz file.
   • Extract the archive using tar:

     sudo tar zxvf jdk-x_linux-x64_bin.tar.gz -C /opt/
     

3. Set the JAVA_HOME Environment Variable:

   • Open Terminal.
   • Open the .bashrc or .profile file in a text editor (e.g., nano ~/.bashrc).
   • Add the following lines:

     export JAVA_HOME=/opt/jdk-x
     export PATH=$JAVA_HOME/bin:$PATH
     

   • Save the file and exit the editor.
   • Reload the profile by running source ~/.bashrc.

4. Verify the Installation:

   • Open Terminal.
   • Type javac -version and press Enter.
   • Type java -version and press Enter.
   • Both commands should display the version numbers of the JDK and JRE, confirming a successful installation.

4. Compile and Run a Simple Java Program

1. Create a Java File:

   • Open a text editor (e.g., Notepad, Visual Studio Code, Sublime Text).
   • Enter the following simple Java program:

     public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); }
     }
     

   • Save the file as HelloWorld.java.

2. Compile the Java Program:

   • Open Command Prompt (Windows), Terminal (macOS/Linux).
   • Navigate to the directory containing HelloWorld.java.
   • Compile the program using javac:

     javac HelloWorld.java
     

   • This will generate a HelloWorld.class file in the same directory.

3. Run the Compiled Program:

   • Run the program using java:

     java HelloWorld
     

   • You should see the output:

     Hello, World!
     

5. Install an Integrated Development Environment (IDE) (Optional)