Changing the Java Runtime Environment on Windows and Linux

Whether you're managing multiple Java versions or need to switch to a different Java runtime, understanding how to change the Java runtime environment is crucial. This guide walks you through the process on both Windows and Linux operating systems, providing detailed steps and explanations to ensure a smooth transition.

Overview

The Java runtime environment is a critical component of developing and running Java applications. By changing the Java runtime, developers can tailor their development environment to their specific needs. This guide covers the essential steps to update the Java runtime on both Windows and Linux.

Changing Java Runtime on Windows

Here are the detailed steps to change the Java runtime on a Windows system:

Open the Control Panel. You can do this by typing 'Control Panel' into the search bar and clicking the result.

Go to 'System'. Here, you will find the 'Advanced system settings' button on the left panel. Click on it to open the System Properties window.

Click on the 'Environment Variables' button. This will open the Environment Variables window.

Under 'System Variables', find the 'Path' variable, select it, and click 'Edit'. If the variable is not listed, you may need to create it.

Click 'New', and add the path to your Java installation's JRE_HOME (or JAVA_HOME) directory if it's not already listed. For example, if your Java installation is located in C:Program FilesJavajdk-17, add this path to the list.

It's important to ensure that the old Java path is removed from the Path variable. You can do this by selecting the old path and clicking 'Remove'.

Click 'OK' to close the 'Edit environment variable' window.

Go back to the 'Environment Variables' window and under 'System Variables', find the 'Path' variable again. Click 'Edit' and append the bin subdirectory to the existing Path variable. For example, if the current Path is C:Program FilesJavajdk-17, it should become C:Program FilesJavajdk-17bin.

Click 'OK' to save the changes.

Open a new Command Prompt or PowerShell window. Type the following command to verify that the new Java runtime is correctly set:

java -version

You should see the version information of the newly installed Java runtime.

Changing Java Runtime on Linux

Here are the detailed steps to change the Java runtime on a Linux system:

To change the Java runtime on a Linux system, you will need to modify the .bashrc or .bash_profile. These files are used to set environment variables for your terminal session.

Edit the .bashrc or .bash_profile file using a text editor like vi or nano. You can open it with the following command:

vi ~ or vi ~_profile

Add the following lines to the file:

.bashrc:

.profile:

export JAVA_HOMEyour-java-direxport PATH$PATH:$JAVA_HOME/bin

Replace your-java-dir with the actual path to the Java installation directory, such as /usr/lib/jvm/java-11-openjdk-amd64.

Save the file and close the editor.

To apply the changes without restarting your terminal, run the following command:

. ~ or . ~_profile

To verify that the new Java runtime is correctly set, type the following command in the terminal:

java -version

You should see the version information of the newly installed Java runtime.

By following these steps, you can effectively change the Java runtime environment on your Windows or Linux system, ensuring that your Java applications run with the desired version.

Conclusion

Managing the Java runtime environment is a common task for developers and system administrators. Follow the detailed steps provided in this guide to successfully change your Java runtime on both Windows and Linux systems. Remember to update the JAVA_HOME and PATH variables appropriately to ensure that your new Java installation takes precedence over the old one.

For further reading and detailed troubleshooting, refer to the official Oracle Java Documentation or the Red Hat Java Runtime Environment Guide.