增加一天的算法

import java.util.Scanner;

/**
* @author Jackie
* 日期加一
*/
public class DateAddOneTest {
int day;
int month;
int year;
boolean leapYear;
/*定义带有年月日的构造函数*/

DateAddOneTest(int year, int month, int day){
  this.year = year;
  this.month = month;
  this.day = day;
}
/*判断是否为闰年*/

public boolean isLeapYear(int year){
  return ((year%4 == 0 && year%100 != 0) || year%400 == 0);
}

public static void main(String[] args){
/*从控制台输入一个日期，一次输入年-回车月-回车-日回车*/

  System.out.println("Please enter the year,the month and the day:");
  Scanner scanner = new Scanner(System.in);
  System.out.print("year:");
  int year = scanner.nextInt();
  System.out.print("month:");
  int month = scanner.nextInt();
  System.out.print("day:");
  int day = scanner.nextInt();
/*取输入的“日”变量*/
/*检验是否有效 */

  if(day <= 0 || day >=32)
   {
    System.out.println("Wrong day below or equals zero or overflow.");
    //如果输入日期有错误，则退出。
    System.exit(0);
   }

  DateAddOneTest addOne = new DateAddOneTest(year , month , day);
//得到二月 
switch(month){
   case 2:
//判断是否为闰年
    if(addOne.isLeapYear(year) == true){
     if(day < 29) day++;
     else if(day == 29) { month++; day = 1; }
     else {System.out.println("Day error.");}
    }
    else if(day < 28)
    {day++;}
     else if(day == 28) { month++; day = 1;}
     else {System.out.println("Day error.");}
    }
    System.out.println(year + "年/" + month + "月/" + day + "日");
    System.out.println(day + "日/" + month + "月/" + year + "年");
    System.out.println(month + "月/" + day + "日/" + year + "年");
    break;
   case 1:
   case 3:
   case 5:
   case 7:
   case 8:
   case 10:
   case 12:
    if(day < 31) day++;
    else if(day ==31) { month++; day = 1; }
    else {System.out.println("Day error.");}
    System.out.println(year + "年/" + month + "月/" + day + "日");
    System.out.println(day + "日/" + month + "月/" + year + "年");
    System.out.println(month + "月/" + day + "日/" + year + "年");
    break;
   case 4:
   case 6:
   case 9:
   case 11:
    if(day < 30) day++;
    else if(day ==31) { month++; day = 1; }
    else {System.out.println("Day error.");}
    break;
   default :
    System.out.println("Input error!!!");
    break;
  }
}
}