How to Install Java on Gnu/Linux Distros
GNU/Linux Installing Java Guide
Hi! The linked Tutorials Show you Step-by-Step How to Install Java JRE/JDK in GNU/Linux Distributions.
And the OpenJDK for Linux (Open Java Development Kit) is a Free and Open Source Implementation of the Java Platform, Standard Edition (Java SE).
Moreover, the Java JDK includes the JRE and other “Tools for Developing, Debugging, and Monitoring Java Applications”.
Especially relevant: Oracle Java JDK/JRE is based on the OpenJDK Source Code. But in Addition, it contains Closed-Source Components.