install Java - JDK on Ubuntu

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

To set up the Java 7 environment variables such as JAVA_HOME and PATH,
sudo apt-get install oracle-java7-set-default


sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java8-installer