Here you can find the source of startOfDay(Date date, String format)
public static String startOfDay(Date date, String format)
//package com.java2s; /******************************************************************************* * Copyright (c) 2010 Oobium, Inc./*w w w. j av a 2s . com*/ * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Jeremy Dowdall <jeremy@oobium.com> - initial API and implementation ******************************************************************************/ import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class Main { public static Date startOfDay() { return startOfDay(new Date()); } public static Date startOfDay(Date date) { Calendar cal = Calendar.getInstance(); cal.setTime(date); cal.set(Calendar.HOUR_OF_DAY, 0); cal.set(Calendar.MINUTE, 0); cal.set(Calendar.SECOND, 0); cal.set(Calendar.MILLISECOND, 0); return cal.getTime(); } public static String startOfDay(Date date, String format) { SimpleDateFormat sdf = new SimpleDateFormat(format); return sdf.format(startOfDay(date)); } public static String startOfDay(String format) { return startOfDay(new Date(), format); } }