How to Install OpenJDK on Ubuntu 22.04

How to Install OpenJDK on Ubuntu 22.04

OpenJDK (Open Java Development Kit) is a free and open-source implementation of the Java Platform, Standard Edition (Java SE). It’s widely used for building and running Java applications across different environments. If you’re running Ubuntu 22.04 and need to install OpenJDK, follow this step-by-step guide.

Step 1: Update and Upgrade Your System

Before installing any new software, it’s a good idea to update the package lists and upgrade existing packages to their latest versions. Open a terminal and run the following commands:
sudo apt update
sudo apt upgrade

This ensures that your system is up to date and any potential package conflicts are avoided.

Step 2: Check Available Versions of OpenJDK

Ubuntu repositories contain several versions of OpenJDK, such as OpenJDK 11 and OpenJDK 17. To see which versions are available in the repository, use the following command:

sudo apt search openjdk


This will list all the available OpenJDK versions that can be installed.

Step 3: Install OpenJDK

To install a specific version of OpenJDK, for instance, OpenJDK 11 or OpenJDK 17, follow these steps:

• To Install OpenJDK 11 (LTS version):

sudo apt install openjdk-11-jdk


• To Install OpenJDK 17 (the latest LTS version as of Ubuntu 22.04):

sudo apt install openjdk-17-jdk


The openjdk-*-jdk package includes both the Java Development Kit (JDK) and Java Runtime Environment (JRE). If you only need the runtime environment, you can install the openjdk-*-jre package.

Step 4: Verify the Installation

Once the installation is complete, you should verify the version of Java installed on your system. You can check this by running the following command:

java -version


This command should display the installed version of OpenJDK.

Step 5: Configure Default Java Version

If multiple versions of Java are installed, you can configure the default version by using the update-alternatives tool. Run the following command:

This will display a list of all installed Java versions. You can choose the default version by entering the corresponding number.

Step 6: Set JAVA_HOME Environment Variable

It’s often necessary to set the JAVA_HOME environment variable for Java-based applications to function properly. You can set this by editing the ~/.bashrc file or /etc/environment for system-wide configuration.

To set JAVA_HOME for the current user, follow these steps:

1. Open the .bashrc file for editing:

nano ~/.bashrc


2. Add the following line at the end of the file (replace <version> with the installed version, for example, 11 or 17):

3. Save the file and apply the changes:

4. Verify that JAVA_HOME is set correctly:

echo $JAVA_HOME


You should see the path to your installed OpenJDK version.

Step 7: Test Java Installation

To ensure that Java is properly installed and set up, create a simple Java program and run it:

1. Create a file called HelloWorld.java:

2. Add the following Java code:

3. Compile the program using javac (Java compiler):

4. Run the program:

If everything is installed correctly, you should see the output:

Conclusion

Congratulations! You have successfully installed OpenJDK on Ubuntu 22.04. Whether you’re using OpenJDK for developing Java applications or running Java-based software, Ubuntu’s package management system makes it easy to manage your Java environment. You can now start building and running Java applications with OpenJDK on your Ubuntu machine.

If you have multiple versions of Java installed, remember that you can switch between them using update-alternatives or adjust your environment variables as needed.