How to Install Java OpenJDK on Ubuntu Gnu/Linux Distro
GNU/Linux Ubuntu Installing Java OpenJDK Guide
Hi! The linked Tutorials Show you Step-by-Step How to Install Oracle-Sun Java OpenJDK JRE/JDK on Ubuntu GNU/Linux Distribution.
And the OpenJDK for Ubuntu (Open Java Development Kit) is a Free and Open Source Implementation of the Java Platform, Standard Edition (Java SE).
Oracle Java JDK/JRE Installation is based on the OpenJDK source code. In Addition, it contains Closed-Source Components.
As the best Alternative see: How to Install Oracle Official Java JDK on Linux Distros.