The Java Platform Standard Edition Development Kit (JDK) includes
both the runtime environment (Java virtual machine,
the Java platform classes and supporting files) and development tools
(compilers, debuggers, tool libraries and other tools).
The JDK is a development environment for building applications,
applets and components that can be deployed with the
Java Platform Standard Edition Runtime Environment.

More details:
https://developer.oracle.com/java/

This SlackBuild will repackage official Oracle JDK archive.
You must accept the Oracle Technology Network License Agreement
for Oracle Java SE to download this software

https://www.oracle.com/technetwork/java/javase/downloads/jdk13-downloads-5672538.html

After installation you will need to log out from the system and log in back
for environment variables get updated.