Here you can find the source of getDayOfWeek(Date date)
public static int getDayOfWeek(Date date)
//package com.java2s; import java.util.Calendar; import java.util.Date; import java.util.GregorianCalendar; public class Main { public static int getDayOfWeek(String year, String month, String day) { Calendar cal = new GregorianCalendar(Integer.valueOf(year) .intValue(), Integer.valueOf(month).intValue() - 1, Integer .valueOf(day).intValue()); return cal.get(Calendar.DAY_OF_WEEK); }/*from w ww . j av a2 s . c om*/ public static int getDayOfWeek(String date) { String[] temp = null; if (date.indexOf("/") > 0) { temp = date.split("/"); } if (date.indexOf("-") > 0) { temp = date.split("-"); } return getDayOfWeek(temp[0], temp[1], temp[2]); } public static int getDayOfWeek(Date date) { Calendar cal = new GregorianCalendar(); cal.setTime(date); return cal.get(Calendar.DAY_OF_WEEK); } }