Install Oracle Java 7 on Ubuntu

1. install java
sudo add-apt-repository ppa:webupd8team/java

sudo apt-get update 

sudo apt-get install oracle-java7-installer

2. switch java

sudo update-java-alternatives -l
sudo update-alternatives --config java
sudo update-alternatives --config javac

4. for Eclipse, in eclipse.ini

/usr/lib/jvm/jdk1.7.0/bin/java