Install Java JDK 7 in Ubuntu 12.04

Install Java JDK 7 in Ubuntu 12.04

This package provides Oracle Java JDK 7 (which includes JRE and the Java browser plugin). 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 install 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:
java version “1.7.0_07″
Java(TM) SE Runtime Environment (build 1.7.0_07-b10)
Java HotSpot(TM) Server VM (build 23.3-b01, mixed mode)
4. Check what compiler is used:
#javac -version
The correct answer:
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