Program: How to format date into user define format?

package com.java2novice.date;

import java.text.SimpleDateFormat;
import java.util.Date;

public class MyDateFormatter {

	public static void main(String a[]){
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy.MM.dd G 'at' HH:mm:ss z");
		//Look at SimpleDateFormat documentation for more format details
		System.out.println("yyyy.MM.dd G 'at' HH:mm:ss z  ---> "+sdf.format(new Date()));
		sdf = new SimpleDateFormat("hh 'o''clock' a, zzzz");
		System.out.println("hh 'o''clock' a, zzzz  ---> "+sdf.format(new Date()));
	}
}

yyyy.MM.dd G 'at' HH:mm:ss z  ---> 2012.04.08 AD at 14:47:01 GMT+05:30
hh 'o''clock' a, zzzz  ---> 02 o'clock PM, GMT+05:30