日期算法

页面上有一个这一年的多少周，代码中怎么算出是这一年的几月几号到几月几号？算法 --------------------编程问答-------------------- SimpleDateFormat sdf = new SimpleDateFormat("MM dd yyyy");
Calendar cal = Calendar.getInstance();
cal.set(Calendar.WEEK_OF_YEAR, 23);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
System.out.println(sdf.format(cal.getTime())); --------------------编程问答--------------------

引用 1 楼 soton_dolphin 的回复:

SimpleDateFormat sdf = new SimpleDateFormat("MM dd yyyy");
Calendar cal = Calendar.getInstance();
cal.set(Calendar.WEEK_OF_YEAR, 23);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
System.out.println(sdf.format(cal.getTime()));

+1024 --------------------编程问答-------------------- 如果是js的话，返回某一年的第几周的第一天的方法^_^：



function getDateByYearAndWeek(year, weeks){

    var date = new Date(year, 0, 1);

    if (weeks == 1)

        return date;

    var weekday = date.getDay();

    var time = date.getTime();

    time += ((weeks - 1) * 7 - weekday) * 24 * 3600000;

    date.setTime(time);

    return date;

}

--------------------编程问答--------------------



        SimpleDateFormat sdf = new SimpleDateFormat("MM dd yyyy");

        Calendar cal = Calendar.getInstance();

        cal.set(Calendar.WEEK_OF_YEAR, 23);

        cal.set(Calendar.DAY_OF_WEEK, 1);

        System.out.println(sdf.format(cal.getTime()));//周日

        cal.set(Calendar.DAY_OF_WEEK, 7);

        System.out.println(sdf.format(cal.getTime()));//周一

--------------------编程问答--------------------

引用 4 楼 ghostkngiht 的回复:



        SimpleDateFormat sdf = new SimpleDateFormat("MM dd yyyy");

        Calendar cal = Calendar.getInstance();

        cal.set(Calendar.WEEK_OF_YEAR, 23);

        cal.set(Calendar.DAY_OF_WEEK, 1);

        System.out.println(sdf.format(cal.getTime()));//周日

        cal.set(Calendar.DAY_OF_WEEK, 7);

        System.out.println(sdf.format(cal.getTime()));//周一

cal.set(Calendar.WEEK_OF_YEAR, 23);//这个可以设置一个变量，就是你想要的结果，当你输入第几周的时候就会输出周日到周一的日期 --------------------编程问答--------------------

Scanner sc1=new Scanner(System.in);

		System.out.println("请输入年份:");

		int year=sc1.nextInt();

		Scanner sc=new Scanner(System.in);

		System.out.println("请输入第几周:");

		int week=sc.nextInt();

		SimpleDateFormat sdf = new SimpleDateFormat("MM dd yyyy"); 

		Calendar cal = Calendar.getInstance();

		cal.set(year, 1, 1);

		cal.set(Calendar.WEEK_OF_YEAR, week);        

		cal.set(Calendar.DAY_OF_WEEK, 1);        

		System.out.println(sdf.format(cal.getTime()));//周日       

		cal.set(Calendar.DAY_OF_WEEK, 7);        

		System.out.println(sdf.format(cal.getTime()));//周一

先输入哪一年，然后再输入第几周，就会出现那一年的日期了。

补充：Java ,  Web 开发