输入某年某月某日 判断其是那一年的第多少天

[java]代码库

           Scanner scan = new Scanner(System. in);

           System. out .print("请输入年:" );
            int year = scan.nextInt();

           System. out .print("请输入月：" );
            int month = scan.nextInt();

           System. out .print("请输入日：" );
            int day = scan.nextInt();

            int sum = 0; //计数器
            switch(month){
                 case 12:
                     sum += 30;
                 case 11:
                     sum += 31;
                 case 10:
                     sum += 30;
                 case 9:
                     sum += 31;
                 case 8:
                     sum += 31;
                 case 7:
                     sum += 30;
                 case 6:
                     sum += 31;
                 case 5:
                     sum += 30;
                 case 4:
                     sum += 31;
                 case 3:
                      if(year % 4 == 0 && year % 100 != 0 || year % 400 == 0){
                           sum += 29;
                     } else{
                           sum += 28;
                     }
                 case 2:
                     sum += 31;
                 case 1:
                     sum += day;
           }

           System. out .println("当年的第 " + sum + " 天" );