DebugPoint published a tutorial about installing Java in Arch Linux and Manjaro.
How to Install Java in Arch Linux and Manjaro [JDK and JRE]
This quick beginner’s guide explains the steps you need to install Java in Arch Linux and related distributions such as Manjaro. There are two versions of Java (Java Development Kit – JDK and Java environment) is available Arch Linux (or any Linux). One is the free and open-source version implementation of Oracle Java SE.
