Ubuntu 12.04, 14.04 install Oracle Java

Step one: If open Java is already installed on the system, you need to clean it up and skip the process

sudo apt-get purge openjdk*

Step Two: Install

sudo apt-get install Software-properties-common

Step three: Add a trusted software source:

sudo add-apt-repository Ppa:webupd8team/java

Fourth step, update

sudo apt-get update

Fifth Step: Install Java

Java6

sudo apt-get install Oracle-java6-installer

Java7

sudo apt-get install Oracle-java7-installer

Java8

sudo apt-get install Oracle-java8-installer