OpenJDK 21 Installation in Debian Bookworm – Step-by-step

How to Install

2. 2. Downloading OpenJDK 21

   Download OpenJDK 21 GNU/Linux Package

   OpenJDK 21 tar.gz Linux/x64

   Downloading OpenJDK 21 for GNU/Linux Systems.

   If you don’t see the Current Release, just access the Latest one and then on the Left Sidebar you should find it.

3. 3. Installing OpenJDK 21

   Now to Install OpenJDK 21 for Debian
   Simply play:

   sudo tar xvzf ~/Downloads/openjdk-21*.tar.gz -C /usr/lib/jvm/

   But if yuo are in Trouble to Find it out on Terminal then See: How to Access Downloads Folder from Browser.

4. 4. Setting Up Java

   Next to Set Up Oracle java OpenJDK 21
   You can directly Copy & Paste the Commands into Terminal..

   sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-21*/bin/java 1165

   sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk-21*/bin/javac 1165

   sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/jdk-21*/bin/jar 1165

   sudo update-alternatives --install /usr/bin/javaws javaws /usr/lib/jvm/jdk-21*/bin/javaws 1165

   Checking or Setting the System Java Version in Use with

   sudo update-alternatives --config java

   And for the Java Compiler instead:

   sudo update-alternatives --config javac

   To Switch of Java Version Just Enter the Selection Number on First, Column. :)

   

5. 5. Setting Up Env

   (Optional) Setting JAVA_HOME User Environment Variable
   And Edit the Bash environment Configuration file

   nano $HOME/.bashrc

   Append:

   export JAVA_HOME=/usr/lib/jvm/jdk-21[Release]

   Replace [Release] with the actual one on the above Command.
   Possibly to Check the JDK 21 exact PATH use in another window:

   ls /usr/lib/jvm/

   Ctr+x to Save & Exit from nano Editor :)
   Next to Load the New Bash Environment:

   bash

6. Finally, Test New Java JDK 21 Installation

   java -version