java中获取当月1号零时零分的时间

/**
  * 获得当月1号零时零分零秒
  * @return
  */
public Date initDateByMonth(){
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(new Date());
    calendar.set(Calendar.DAY_OF_MONTH, 1);
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    return calendar.getTime();
}