Return a Date set to the first possible millisecond of the day, just after midnight in Java

/*w w w. j a  va2  s.c  om*/
import java.util.Calendar;
import java.util.Date;

public class Main {
   public static void main(String[] argv){
        System.out.println(getStartOfDay(new Date()));
   }
        
  /**
   * Returns a Date set to the first possible millisecond of the day, just
   * after midnight. If a null day is passed in, a new Date is created.
   * midnight (00m 00h 00s)
   */
  public static Date getStartOfDay(Date day) {
      return getStartOfDay(day, Calendar.getInstance());
  }
  
  
  /**
   * Returns a Date set to the first possible millisecond of the day, just
   * after midnight. If a null day is passed in, a new Date is created.
   * midnight (00m 00h 00s)
   */
  public static Date getStartOfDay(Date day, Calendar cal) {
      if (day == null) day = new Date();
      cal.setTime(day);
      cal.set(Calendar.HOUR_OF_DAY, cal.getMinimum(Calendar.HOUR_OF_DAY));
      cal.set(Calendar.MINUTE,      cal.getMinimum(Calendar.MINUTE));
      cal.set(Calendar.SECOND,      cal.getMinimum(Calendar.SECOND));
      cal.set(Calendar.MILLISECOND, cal.getMinimum(Calendar.MILLISECOND));
      return cal.getTime();
  }
}

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  The ASF licenses this file to You
 * under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.  For additional information regarding
 * copyright in this work, please see the NOTICE file in the top level
 * directory of this distribution.
 */