Here you can find the source of getFirstDayOfWeek(final Date date)
public static Date getFirstDayOfWeek(final Date date)
//package com.java2s; /*//from ww w . jav a 2 s . co m * #%L * Webstar Newsletter * %% * Copyright (C) 2013 Webstar Csoport Kft. * %% * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this program. If not, see * <http://www.gnu.org/licenses/gpl-3.0.html>. * #L% */ import java.util.*; public class Main { public static Date getFirstDayOfWeek(final Date date) { if (dayOfWeek(date) == 1) { return addDays(date, -6); } return addDays(date, -1 * (dayOfWeek(date) - 2)); } public static int dayOfWeek(final Date date) { Calendar calendar = GregorianCalendar.getInstance(); calendar.setTime(date); int weekday = calendar.get(Calendar.DAY_OF_WEEK); return weekday; } public static Date addDays(Date eredeti, int mennyit) { return add(eredeti, Calendar.DAY_OF_YEAR, mennyit); } public static Date add(Date eredeti, int mihez, int mennyit) { if (eredeti == null) { return null; } Calendar cal = new GregorianCalendar(); cal.setTime(eredeti); cal.add(mihez, mennyit); return cal.getTime(); } }