Scanner str = new Scanner(System.in);
System.out.print("请输入年份：");
int Year = str.nextInt();
System.out.print("请输入月份：");
int Month = str.nextInt();
System.out.print("请输入天：");
int Day = str.nextInt();
switch (Month) {
case 1:break;
case 2:Day += 31;break;
case 3:Day += 59;break;
case 4:Day += 90;break;
case 5:Day += 120;break;
case 6:Day += 151;break;
case 7:Day += 181;break;
case 8:Day += 212;break;
case 9:Day += 243;break;
case 10:Day += 273;break;
case 11:Day += 304;break;
case 12:Day += 334;break;
default:System.out.print("输入有误！");
}
System.out.print("该天是当年的第" + Day + "天");
switch确定某天是该年第几天
原文：http://www.cnblogs.com/quanby/p/5326676.html
