about date

gistfile1.txt

package com.demo;

import java.util.Calendar;
import java.util.Date;

public class DemoDateUtil {
  //static DateUtil du = new DateUtil();

	/**
	 * @param args
	 */
	@SuppressWarnings("deprecation")
	public static void main(String[] args) {
		Calendar cal=Calendar.getInstance();
		Date date=cal.getTime();
		Date du1=getStartOfLastWeek(date);
		Date du2=getStartOfWeek(date);
		Date du3=getStartOfMonth(date);
		Date du4=getStartOfLastMonth(date);
		Date du5=getStartOfNextMonth(date);
		System.out.println(du1.toLocaleString());

		System.out.println(du2.toLocaleString());
		System.out.println(du3.toLocaleString());
		System.out.println(du4.toLocaleString());
		System.out.println(du5.toLocaleString());
		/**
		 * 2013-3-4 17:49:44
		 * 2013-3-11 17:49:44
		 * 2013-3-1 17:49:44
		 * 2013-2-1 17:49:44
		 * 2013-4-1 17:49:44
		 */
	}
    /**
     * Start of the month
     * 
     * @param inDate
     * @return
     */
    public static Date getStartOfMonth(Date inDate) {
        if (inDate == null)
            return null;

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(inDate);

        calendar.set(Calendar.DAY_OF_MONTH, 1);
        return calendar.getTime();
    }

    /**
     * Start of next month
     * 
     * @param inDate
     * @return
     */
    public static Date getStartOfNextMonth(Date inDate) {
        if (inDate == null)
            return null;

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(inDate);
        calendar.add(Calendar.MONTH, 1);
        calendar.set(Calendar.DAY_OF_MONTH, 1);
        return calendar.getTime();
    }

    /**
     * Start of last month
     * 
     * @param inDate
     * @return
     */
    public static Date getStartOfLastMonth(Date inDate) {
        if (inDate == null)
            return null;

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(inDate);
        calendar.add(Calendar.MONTH, -1);
        calendar.set(Calendar.DAY_OF_MONTH, 1);
        return calendar.getTime();
    }

    /**
     * Start of last week
     * 
     * @param inDate
     * @return
     */
    public static Date getStartOfLastWeek(Date inDate) {
        if (inDate == null)
            return null;

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(inDate);

        if (calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
            calendar.add(Calendar.WEEK_OF_MONTH, -1);
        }

        calendar.add(Calendar.WEEK_OF_MONTH, -1);

        calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        return calendar.getTime();
    }
    /**
     * Start of the week
     * 
     * @param inDate
     * @return
     */
    public static Date getStartOfWeek(Date inDate) {
        if (inDate == null)
            return null;

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(inDate);

        if (calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
            calendar.add(Calendar.WEEK_OF_MONTH, -1);
        }
        calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        return calendar.getTime();
    }
}