https://tecadmin.net/install-oracle-java-8-ubuntu-via-ppa/
Java8 add repo, update, and install
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java8-installer
Set Java8 as Default
sudo apt-get install oracle-java8-set-default
Check Java Version
java -version
java version "1.8.0_191 "
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.171-b12, mixed mode)
Set JAVA_HOME & JDK_HOME
Seen this done through export, but so be it...
cat >> /etc/environment <<EOL
JAVA_HOME=/usr/lib/jvm/java-8-oracle
JRE_HOME=/usr/lib/jvm/java-8-oracle/jre
EOL
Book traversal links for Ubuntu: Java JDK8 apt-get