OpenJDK offers a free version of Java. At this time, the latest version if Java 13. These are the steps required to install OpenJDK 13 on your Ubuntu 19.04 or Ubuntu 20.04.
First, you need to have a machine with the Ubuntu system installed and provides root access.
How to Install OpenJDK 13 on Ubuntu?
Open a new terminal and run the following command to install Java 13 on Ubuntu 19:
$ sudo apt install openjdk-13-jdk
Next, you can check the installed version using the following command
$ java -version
openjdk version "13" 2019-09-17
OpenJDK Runtime Environment (build 13+13-Ubuntu-0ubunt1)
OpenJDK 64-Bit Server VM (build 13+13-Ubuntu-0ubunt1, mixed mode, sharing)