OpenJDK 21 Installation in Linux Mint – Step-by-step

How to Install

2. 2. Enabling OpenJDK 21 PPA

   Add OpenJDK 21 PPA for Ubuntu GNU/Linux

   Enabling OpenJDK 21 Repo for Ubuntu

   OpenJDK 21 PPA for Ubuntu.

   Skip for Mint 20+.

3. 3. Installing OpenJDK 21

   Then to Install OpenJDK 21 in Mint
   First, to look up all the available flavors play:

   apt search openjdk-21

   So next for OpenJDK JDK 21 issue:

   sudo apt install openjdk-21-jdk

   Where for the Java Runtime instead:

   sudo apt install openjdk-21-jre

   Authenticate with the User Admin Pass.
   If Got “User is Not in Sudoers file” then see: How to Enable sudo
   Now to Check the current Java:

   java -version

   And in output you find it:

   

   Finally, to check for available Java releases:

   apt search openjdk | grep jdk

4. 4. Managing Java Versions

   So now to Manage Multiple Java on System
   Use the update-alternatives as:

   sudo update-alternatives --config java

   If more than one then choose the wanted Release from list:

   

   And in case of a JDK Setup you may also switch the Java Compiler with:

   sudo update-alternatives --config javac