输入年月日查询是这一年的第几天(详解)

//导包
import java.util.Scanner;

//声明一个类名为Test的类
public class Test {
  //mian方法  程序入口
  public static void main(String[] args) {
    // 输入年月日查询是这一年的第几天
    
    //键盘输入
    Scanner scan = new Scanner(System.in);
    System.out.println("******输入年月日查询是这一年的第几天******");
    //定义二月的天数
    int febDay = 0;
    //定义总天数
    int sumDays = 0;
    System.out.print("请您输入年份：");
    //获取键盘输入值---获取年份
    int year = scan.nextInt();
    System.out.print("请您输入月份：");
    //获取键盘输入值---获取月份
    int month = scan.nextInt();
    System.out.print("请您输入日：");
    //获取键盘输入值---获取日
    int day = scan.nextInt();
    //判断年月日是否符合条件  符合执行计算操作  否则输出错误
    if (year >= 0 && month > 0 && month < 13 && day > 0 && day < 32) {
      //判断年份是否是闰年  是闰年二月29天  否则二月28天
      if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
        febDay = 29;
      } else {
        febDay = 28;
      }
      //判断选择月份
      switch (month) {
      //月份为12时
      case 12:
        //计算总天数
        sumDays = 31 * 6 + 30 * 4 + febDay + day;
        //停止循环
        break;
      case 11:
        sumDays = 31 * 6 + 30 * 3 + febDay + day;
        break;
      case 10:
        sumDays = 31 * 5 + 30 * 3 + febDay + day;
        break;
      case 9:
        sumDays = 31 * 5 + 30 * 2 + febDay + day;
        break;
      case 8:
        sumDays = 31 * 4 + 30 * 2 + febDay + day;
        break;
      case 7:
        sumDays = 31 * 3 + 30 * 2 + febDay + day;
        break;
      case 6:
        sumDays = 31 * 3 + 30 + febDay + day;
        break;
      case 5:
        sumDays = 31 * 2 + 30 + febDay + day;
        break;
      case 4:
        sumDays = 31 * 2 + febDay + day;
        break;
      case 3:
        sumDays = 31 + febDay + day;
        break;
      case 2:
        sumDays = 31 + day;
        break;
      case 1:
        sumDays = day;
        break;
      }
      // 输出
      System.out.println("您输入年月日是这一年的第" + sumDays + "天");
    }else{
      // 输出错误信息
      System.out.println("输入有误！");
    }
  }
}