例题

输入某年某月某日，判断这一天是这一年的第几天？

package a;
import java.util.*;
public class ScannerTest {
public static void main(String[] args) {
int year, month, day;
int days = 0;
int d = 0;
int e;
input fymd = new input();
do {
e = 0;
System.out.print("输入年：");
year = fymd.input();
System.out.print("输入月：");
month = fymd.input();
System.out.print("输入天：");
day = fymd.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 = 1; 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 + "-" + month + "-" + day + "是这年的第" + (d + day) + "天。");
}
}

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

输出9*9口诀。