java 输入某年某月某日，判断这一天是这一年的第几天

 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); } }