GNU/Linux Kubuntu 18.04 Installing Java JDK Guide
This tutorial will guide you step-by-step on How to Install Oracle Java SE Development Kit on Kubuntu 18.04 Bionic LTS GNU/Linux.
And the Oracle Java SE Kubuntu Bionic Release includes:
- OpenJDK Java Development Kit
- Oracle Java Development Kit
Moreover, the Java OpenJDK (Open Java Development Kit) is the Free and Open Source Implementation of the Java Platform, Standard Edition (Java SE).
Where the Oracle JRE/JDK is based on the OpenJDK Source Code. In Addition, it contains Closed-Source Components.

GNU/Linux Kubuntu 18.04 Java Development Kit Installation Guide