Installing Sun JDK 7 on Ubuntu 12.04 / 12.10 / 13.04:

• Download the sun jdk 7 tar file 
• Extract the tar file:

tar -xvzf jdk-7u11-linux-x64.tar.gz

• For Ubuntu 13.04: There is no longer a jvm folder in /usr/lib, therefore create jvm folder

sudo mkdir /usr/lib/jvm

• Move extracted folder to this location:

sudo mv jdk1.7.0_11 /usr/lib/jvm/jdk1.7.0_11

• Install new java source in system:

sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0_11/bin/javac 1
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.7.0_11/bin/java 1
sudo update-alternatives --install /usr/bin/javaws javaws /usr/lib/jvm/jdk1.7.0_11/bin/javaws 1

• Choose default java:

sudo update-alternatives --config javac
sudo update-alternatives --config java
sudo update-alternatives --config javaws

• java version test:

java -version

• Verify the symlinks all point to the new java location:

ls -la /etc/alternatives/java*