Install Open JDK on WSL

This article provides detailed steps to install Java Development Kit (JDK) on WSL. 

Step by step guide

The following steps are performed on a Debian WSL distro. You can apply similar steps on other distros like openSUSE, Ubuntu, etc.

1.  Run the following command to update package index:
   

   sudo apt update

2. Check whether Java is installed already:
   

   java --version

   The command will output the following text if Java is not installed yet: -bash: java: command not found.
   

3. Install OpenJDK via the following command:
   

   sudo apt-get install openjdk-8-jdk

   Type Y to continue when asked. 

   Wait until the installation is completed.

4. Check the version again:
   

   ~$ java -version
   openjdk version "1.8.0_275"
   OpenJDK Runtime Environment (build 1.8.0_275-8u275-b01-1~deb9u1-b01)
   OpenJDK 64-Bit Server VM (build 25.275-b01, mixed mode)

Configure JAVA_HOME

Configure JAVA_HOME environment variable is optional but I highly recommend it especially if you want to install Hadoop, Spark, Hive, HBase or any other Java based frameworks. 

To do this, we need to find out where JDK is installed:

$ readlink -f $(which java)
/usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java

As printed out, JDK is installed in folder /usr/lib/jvm/java-8-openjdk-amd64.
Run the following command to edit .bashrc file:

vi ~/.bashrc

Add the following line to the content:

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

Save the file and then run the following command:

source ~/.bashrc

Run the following command to make sure it is effective:

~$ echo $JAVA_HOME
/usr/lib/jvm/java-8-openjdk-amd64