输入某年某月某日，判断这一天是这一年的第几天？

public static void main(String[] args) {
int year,month,day;
int days = 0;
int d = 0;
int e;

do{
e=0;
System.out.println("输入年：");
year=input();
System.out.println("输入月：");
month=input();
System.out.println("输入日：");
day=input();
if(year<0||month<0||month>12||day<0||day>31){
System.out.println("输入错误，请重新输入");
e=1;
}
}while(e==1);
for (int i = 0; i <month; i++) {
switch(i){
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%400==0)||(year%4==0&&year%100!=0)){
days =29;
}else{
days =28;
}
break;
}
d+=days;
}
System.out.println(year+"年"+month+"月"+day+"日"+"是这年的第"+(d+day)+"天");

}
public static int input(){
int value = 0;
Scanner s = new Scanner(System.in);
value = s.nextInt();
return value;
}
}