I installed Oracle Java Jdk 12 from here:
But the installation explanation is cryptic to me:
Unpack the tarball and install the JDK: $ tar zxvf jdk-12.interim.update.patch_linux-x64_bin.tar.gz
The Java Development Kit files are installed in a directory called jdk-12.interim.update.patch.
But it doesn't tell what command to use to install it.