Here you can find the source of format(Date date)
public static String format(Date date)
//package com.java2s; //License from project: Open Source License import java.text.SimpleDateFormat; import java.util.Date; public class Main { private static final SimpleDateFormat defaultFormater = new SimpleDateFormat("yyyyMMdd"); private static final SimpleDateFormat customizedFormater = new SimpleDateFormat("yyyyMMdd"); public static String format(Date date, String pattern) { synchronized (customizedFormater) { if (null != pattern && !"".equals(pattern.trim())) { customizedFormater.applyPattern(pattern); } else { throw new IllegalArgumentException("pattern can not be empty"); }//www . j a va2 s.c o m return customizedFormater.format(date); } } public static String format(Date date) { synchronized (defaultFormater) { return defaultFormater.format(date); } } }