Install Oracle Java 8 in Ubuntu 12.04.

Run in terminal simple comands:

1. Update repositories and install Java:
   
   sudo add-apt-repository ppa:webupd8team/java
   sudo apt-get update && sudo apt-get install oracle-java8-installer
2. Check java version:
   
   java -version
   
   Output must be similar to:
   
   java version "1.8.0-ea"
   Java(TM) SE Runtime Environment (build 1.8.0-ea-b54)
   Java HotSpot(TM) Server VM (build 24.0-b21, mixed mode)
3. If you have several version of Java, you can switch between them:
   
   Check all installed JVM  on your computer:
   sudo update-java-alternatives -l
   
   Choose JVM and switch:
   sudo update-java-alternatives -s java-8-oracle