How to Install Oracle JDK 12 on Ubuntu 18.04 Bionic LTS

Installing

2. 2. Downloading Oracle JDK 12

   Download Oracle JDK 12 GNU/Linux Package

   Oracle JDK 12 .deb 64-bit

   Downloading Oracle JDK 12 for GNU/Linux Systems

3. 3. Installing Oracle JDK 12

   Then to Setup Oracle JDK 12 on Ubuntu 18.04
   First, Access the Target, usually in the Downloads folder:
   (But if downloaded with Firefox it can be instead into /tmp/mozilla*)

   cd && cd Downloads

   Now to Confirm the Package is there do:

   ls .

   Finally, to Install JDK 12 simply:

   sudo dpkg -i jdk-12*.deb

4. 4. Setting Up Oracle JDK 12

   Now to Install JDK 12 into System

   sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-12/bin/java 1065

   sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk-12/bin/javac 1065

   sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/jdk-12/bin/jar 1065

5. 5. Switching to Java 12

   Finally, to Switch Java to JDK 12
   This is Valid only if you have to Manage more than One Java Releases:

   sudo update-alternatives --config java