You can follow this tutorial to install JAVA OpenJDK in all the Ubuntu versions. Following are the steps to install OpenJDK JAVA on Ubuntu.

1. OpenJDK Packages can available under native apt repository. Below command will find the available java version for Ubuntu OS.
   
   

   # apt-cache search openjdk
   

          Here, OpenJDK JAVA 11 should be present within the list.

2. Hit below command. This will install Java Development Kit (JDK) and Java Runtime Environment (JRE).
   
   

   # sudo apt-get install openjdk-11-jre openjdk-11-jdk
   

3. Verify the Java version using the below command.
   
   

   # java -version
   

   Output :

   openjdk version "11.0.6" 2020-01-14
   OpenJDK Runtime Environment (build 11.0.6+10-post-ubuntu-1ubuntu118.04.1)
   OpenJDK 64-Bit Server(build 11.0.6+10-post-ubuntu-1ubuntu118.04.1, mixed mode, sharing)
   

   
   
   
4. Now, set the Java environment variable. To do that add the below line to /etc/environment.
   
   

   # echo "JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64/" >> /etc/environment
   # source /etc/environment
   

5. Finally, verify the environment value.
   
   

   # echo $JAVA_HOME
   

   Output :

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

     This is it. We are done with the installation of OpenJDK JAVA 11 on Ubuntu.