输入某年某月某日，判断这一天是这一年的第几天？

1.程序分析：以3月5日为例，应该先把前两个月的加起来，然后再加上5天即本年的第几天，特殊情况，闰年且输入月份大于3时需考虑多加一天。

import java.util.*;
public class test {
    public static void main (String[]args){
        int day=0;
        int month=0;
        int year=0;
        int sum=0;
        int leap;
        System.out.print("请输入年,月,日\n");
        Scanner input = new Scanner(System.in);
        year=input.nextInt();
        month=input.nextInt();
        day=input.nextInt();
        switch(month) /*先计算某月以前月份的总天数*/
        {
            case 1:
            sum=0;break;
            case 2:
            sum=31;break;
            case 3:
            sum=59;break;
            case 4:
            sum=90;break;
            case 5:
            sum=120;break;
            case 6:
            sum=151;break;
            case 7:
            sum=181;break;
            case 8:
            sum=212;break;
            case 9:
            sum=243;break;
            case 10:
            sum=273;break;
            case 11:
            sum=304;break;
            case 12:
            sum=334;break;
            default:
            System.out.println("data error");break;
        }
        sum=sum+day; /*再加上某天的天数*/
        if(year%400==0||(year%4==0&&year%100!=0))/*判断是不是闰年*/
        leap=1;
        else
        leap=0;
        if(leap==1 && month>2)/*如果是闰年且月份大于2,总天数应该加一天*/
        sum++;
        System.out.println("It is the the day:"+sum);
    }
}