判断一天是一年中的第几天

package homework08.homework0823;
import java.util.Scanner;

public class Demo {
     
    //判断一天是这一年的第几天
    public static void main(String[] args) {
     
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入年： ");
        int year= scanner.nextInt();
        System.out.print("请输入月： ");
        int month= scanner.nextInt();
        System.out.print("请输入日： ");
        int day= scanner.nextInt();
        int result = 0;
        if (month > 1) {
     
            result += 31;
        }
        if (month > 2) {
     
            if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
     
                result += 29;
            } else {
     
                result += 28;
            }
        }
        if (month > 3) {
     
            result += 31;
        }
        if (month > 4) {
     
            result += 30;
        }
        if (month > 5) {
     
            result += 31;
        }
        if (month > 6) {
     
            result += 30;
        }
        if (month > 7) {
     
            result += 31;
        }
        if (month > 8) {
     
            result += 31;
        }
        if (month > 9) {
     
            result += 30;
        }
        if (month > 10) {
     
            result += 31;
        }
        if (month > 11) {
     
            result += 30;
        }
        System.out.println(result + day);
    }
}

效果图如下：

方法二：用switch写出一天是一年当中的第几天

package homework08.homework0823;

import java.util.Scanner;

public class Demo01 {
     
    public static void main(String[] args) {
     
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入年： ");
        int a = scanner.nextInt();
        System.out.print("请输入月： ");
        int b = scanner.nextInt();
        System.out.print("请输入日： ");
        int c = scanner.nextInt();//从键盘获取年月日;
        int result = 0;//用来接受月份天数
        int flag = 0;//判断：是平年就加0，闰年就加1;
        if ((a % 4 == 0 && a % 100 != 0) || (a % 400 == 0)) {
     
            flag = 1;
        }
        switch (b) {
     
            case 12:
                result += 30;
            case 11:
                result += 31;
            case 10:
                result += 30;
            case 9:
                result += 31;
            case 8:
                result += 31;
            case 7:
                result += 30;
            case 6:
                result += 31;
            case 5:
                result += 30;
            case 4:
                result += 31;
            case 3:
                result = result + 28 + flag;
            case 2:
                result += 31;
            case 1:
                System.out.println(result + c);
                break;
            default:
                System.out.println("输入错误，请重新输入!");
        }
    }
}

效果图如下：