Install Oracle Java 7 in Ubuntu via PPA

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

After the installation finishes, if you wish to see if it was successful, you can run the following command:

          java -version

If for some reason, the Java version in use is not 1.7.0, you can try to run the following command:

          sudo update-java-alternatives -s java-7-oracle

          sudo echo oracle-java7-installer shared/accepted-oracle-license-v1-1 select true | sudo /usr/bin/debconf-set-selections

Removing Oracle Java 7

If you don't want to use Oracle Java (JDK) 7 anymore and want to go back to OpenJDK, all you have to do is remove the Oracle JDK7 Installer and the previous Java (OpenJDK, etc.) version will be used:

sudo apt-get remove oracle-java7-installer