How to install Sun Java6 SDK on Ubuntu Linux

If you type 'javac' (which means java compiler) at terminal, you can see the following message:

jaeheon@ubuntu:~$ javac
'javac' 프로그램은 다음 꾸러미들에서 찾을 수 있습니다:
 * openjdk-6-jdk
 * ecj
 * gcj-4.3
 * java-gcj-compat-dev
 * gcj-4.2
 * jikes-classpath
 * jikes-kaffe
 * kaffe
 * sun-java5-jdk
 * sun-java6-jdk

I recommend the Java Development Kit supported by Sun Microsystems. The latest version is 6. So we can install it with,

jaeheon@ubuntu:~$ sudo apt-get install sun-java6-jdk