this article is about setting up proper jre & jdk on ubuntu linux.

first, let’s install default jre & jdk

sudo apt-get install default-jre
sudo apt-get install default-jdk

then we add webupd8team repository

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update

let’s install oracle’s java 6,7,8

sudo apt-get install oracle-java6-installer
sudo apt-get install oracle-java7-installer
sudo apt-get install oracle-java8-installer

setting up JAVA_HOME variable to java-8-oracle

sudo update-alternatives --config java
export JAVA_HOME=/usr/lib/jvm/java-8-oracle
echo $JAVA_HOME