Calendar的简单实用

1.获取本月第一天是星期几

public static void main(String[] args) {
		Calendar calendar = new GregorianCalendar(2011,9,1);//月份从0开始,0为1月
		int firstDayInWeek=calendar.get(Calendar.DAY_OF_WEEK);
		System.out.println("本月第一天是(数字)：" +firstDayInWeek);
		SimpleDateFormat format = new SimpleDateFormat("E");
		System.out.println("本月第一天是(星期几)：" + format.format(calendar.getTime())); 
	}

2.获取本月天数

	public static void main(String[] args) {
		Calendar cal = Calendar.getInstance();
		cal.set(Calendar.MONTH,cal.get(Calendar.MONTH)+1);
		cal.set(Calendar.DAY_OF_MONTH,1);
		cal.set(Calendar.DATE,cal.get(Calendar.DATE)-1);
		System.out.println("当月天数:"+cal.get(Calendar.DAY_OF_MONTH));
	}

或者public static void main(String[] args) {
		Calendar cal = Calendar.getInstance();
		int maxDayOfMon=cal.getActualMaximum(Calendar.DAY_OF_MONTH);;
		System.out.println("当月天数:"+maxDayOfMon);
	}