根據年份和月份來計算天數

                int year = 2001; //年份
		int month = 4;   //月份
		int days = 0;    //天數
		switch(month){
		case 1:
		case 3:
		case 5:
		case 7:
		case 8:
		case 10:
		case 12:
			days = 31;
			break;
		case 4:
		case 6:
		case 9:
		case 11:
			days = 30;
			break;
		case 2:
			if((year%4==0 && year%100!=0) || year%400==0){
				days = 29;
			}else{
				days = 28;
			}
		}
		System.out.println(year+"年的"+month+"月，共"+days+"天");