michael@michael-laptop:~/Desktop$ javac HelloWorld.java
The program 'javac' can be found in the following packages:
 * openjdk-6-jdk
 * ecj
 * gcj-4.4-jdk
 * gcj-4.6-jdk
 * gcj-4.5-jdk
 * openjdk-7-jdk
Try: sudo apt-get install <selected package>
michael@michael-laptop:~/Desktop$ sudo apt-get install openjdk-6-jdk
Reading package lists... Done
Building dependency tree
Reading state information... Done
openjdk-6-jdk is already the newest version.