How to Check Java Version Installed on Linux

Introduction

Java is an object-oriented programming language used for building platform-independent applications. Knowing how to check the Java version on Linux is important as different applications sometimes require specific Java versions, ensuring compatibility and optimal performance.

Additionally, checking the version helps manage updates and maintain a secure, up-to-date Java environment on your system.

In this tutorial, learn how to check the Java version installed on Linux.

Prerequisites

• A user account with sudo or root privileges.
• Access to the terminal.
• Java installed.

How to Check Java Version on Linux

There are several ways to check the Java version on Linux. The following text presents three different methods.

Method 1: java -version Command

To check the Java version on Linux, run the following:

java -version

The output displays the Java package version installed on your system. In the example above, OpenJDK version 11.0.24 is installed.

Another way to get the Java version is to check the version of the primary Java compiler, javac. Do it with the following command:

javac -version

Method 2: Check Java Path

There are two ways to find the Java directory path. The first option is to run the following command:

update-alternatives --list java

The system responds with the path where Java is installed. Use the path to check the Java version:

/usr/lib/jvm/java-11-openjdk-amd64/bin/java -version

Alternatively, use the whereis command and follow the symbolic links to find the Java path. To do it, take the following steps:

1. Run the command:

whereis java

The output shows that Java is located in /usr/bin/java.

2. List the /usr/bin/java directory content with the ls command:

ls -l /usr/bin/java

The output shows that /usr/bin/java is a symbolic link for /etc/alternatives/java.

3. List the content of the provided path by running:

ls -l /etc/alternatives/java

The output displays /etc/alternatives/java is another symbolic link and that the actual Java directory path is /usr/lib/jvm/java-11-openjdk-amd64/bin/java.

4. Verify the version with:

<em>/usr/lib/jvm/java-11-openjdk-amd64/bin/java.</em> -version

Method 3: Find Java in Installed Packages

You can also prompt the system to list installed packages and search for Java with its version number.

To generate a list of all installed packages, use the command:

sudo apt list --installed

Scroll up or down until you find the Java packages, as shown in this example.

To avoid searching through all installed packages, list Java packages only. Prompt the system to list Java packages by searching for openjdk with grep:

sudo apt list --installed | grep -i openjdk

Conclusion

This article explained how to check the Java version on Linux using three different methods.

Next, learn how to install Java on different Linux distributions, such as Raspberry Pi and Fedora.