Question

我需要编写一个代码来计算日期而不导入Date类。首先，我需要输入有效日期而且我不知道该怎么做。

        Scanner scan = new Scanner(System.in);
    int day,month,year,february;
    System.out.println("please enter three nubers that represent original date");
    day = scan.nextInt();
    month = scan.nextInt();
    year = scan.nextInt();
    if( year <= 0 || day <= 0 || month <= 0 || month > 12 ){
        System.out.println("The original date is " + day + "/" + month + "/" + year +
        " is invalid");
    }
    if (year%100 == 0 || year % 4 != 0)
        february = 28;
        else if (day>28)
        System.out.println("invalid date");
        else if(year%400 == 0)
        february = 29;
        else if(day>29)
            System.out.println("invalid date");
        else if(year%4 == 0)
        february = 29;
        else if(day>29)
            System.out.println("invalid date");

Answer 1

您需要知道每个月的最大天数。最重要的任务是处理不是二月的月份。很难逐行解释，所以我希望代码能说明问题。我可以缩短代码，但是我已经把它留下了，所以它更符合您的代码。 http://www.timeanddate.com/date/leapyear.html

  //january = daysInMonth[0], february = daysInMonth[1]
  int daysInMonth[] = new int[]
  { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  int year = 1800;
  int day = 30;
  int month = 3;
  if (month != 2) //Month is not February
  {
    int daysInEnteredMonth = daysInMonth[month - 1];
    System.out.println("Days in entered month " + daysInEnteredMonth);
    if (day > daysInEnteredMonth)
    {
      System.out.println("invalid date");
    }
  }
  else
  {
    // Month is February
    if (year % 4 != 0)
    {
      daysInMonth[1] = 28;
    }
    else if (year % 400 == 0)
    {
      daysInMonth[1] = 29;
    }
    else if (year % 100 == 0)
    {
      daysInMonth[1] = 28;
    }
    else  //year is divisible by 4
    {
      daysInMonth[1] = 29;
    }
    //Do the comparison
    int daysInEnteredMonth = daysInMonth[month - 1];
    System.out.println("Days in entered month " + daysInEnteredMonth);
    if (day > daysInEnteredMonth)
    {
      System.out.println("invalid date");
    }
  }

Answer 2

一个简单的方法，在给定的年份检查是否是2月29日的一年（闰年，闰日）。

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  where
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Java日期代码，不导入Date类

2 个答案: