Install Java JDK 7 on Ubuntu 12.04

This package provides Oracle Java JDK 7 (which includes JRE, the Java browser plugin and JavaFX). However, you can’t only install Oracle JRE – the PPA only provides the full Oracle JDK7 package.

1. To add our PPA and install the latest Oracle Java (JDK) 7 in Ubuntu, use the commands below:

   sudo add-apt-repository ppa:webupd8team/java

   sudo apt-get update && sudo apt-get install oracle-jdk7-installer

2. After the installation you have enable the jdk:

   update-alternatives –display java

3. Check if Ubuntu uses Java JDK 7

   java -version

   If all went right the answer should be something like this:
   java version “1.7.0_07″
   Java™ SE Runtime Environment (build 1.7.0_07-b10)
   Java HotSpot™ Server VM (build 23.3-b01, mixed mode)
4. Check what compiler is used:

   javac -version

   The correct answer should be like this:
   javac 1.7.0_07
5. Adding JAVA_HOME to environment
   Edit /etc/environment and add JAVA_HOME=/usr/lib/jvm/java-7-oracle to the end of the file.
   First open a Terminal (Applications → Accessories → Terminal), then enter:

   sudo gedit /etc/environment

   Append to the end of the file:
   JAVA_HOME=/usr/lib/jvm/java-7-oracle
6. Removing Oracle JDK 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-jdk7-installer