Install Oracle 8 Java

Install Oracle Java

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

Configure default JVM

sudo update-alternatives --config java

Uninstall Oracle Java

sudo update-alternatives --config java
#choose OpenJDK

sudo update-alternatives --config javac
#choose OpenJDK

sudo rm -rf /usr/lib/jvm/jdk1.7.0_07/
#It will remove the Oracle Java on Ubuntu