/** * 编写程序，计算2013年的某月某日是当年的第多少天？是星期几？已知2013年元旦是星期二。 */import java.util.Scanner;public class Date {    public static void main(String[] args) {        Scanner input=new Scanner(System.in);        System.out.println("请输入年：");        int year=input.nextInt();        System.out.println("请输入月：");         int month=input.nextInt();         System.out.println("请输入日：");        int day=input.nextInt();        int days=0;        int monthDay=0;        int allDay=0;                   if (year <= 0 || month <= 0 || month > 12 || day <= 0 || day > 31) {                  System.out.println("输入错误，请重新输入！");                                }else{                   if(month==1){                       allDay=day;                   } else{           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;               }               monthDay =monthDay+days;           }                   }                   allDay=monthDay+day;                   System.out.println(year +"年 "+month+"月"+day+"日是这一年的第" +allDay+"天。");                   int x=(allDay+1)%7;                   if(x==0){                   System.out.println(year +"年" +month+ "月"+ day+ "日是这一年的星期天" );                       }else {                           System.out.println(year +"年" +month+ "月"+ day+ "日是这一年的星期"+x );                        }            }              }}