Question

我必须保持程序基本，没什么太花哨的。这是我的问题：当我输入日期“11/31/2013”时，它返回“30天常规月份的日输入错误”。我理解这意味着我的If / Else语句和/或我的布尔表达式的结构存在问题。但我似乎无法弄清楚问题所在。感谢任何帮助，谢谢。

这是我的计划：

import java.util.Scanner;

public class DateValidation {

public static void main(String[] args) {

    Scanner keyboard = new Scanner(System.in);
    String date;
    System.out.println("Please enter a date in the following format: mm/dd/yyyy ");
    date = keyboard.next();

    int month = Integer.parseInt(date.substring(0, 2));
    int day = Integer.parseInt(date.substring(3, 5));
    int year = Integer.parseInt(date.substring(6, 10));
    boolean isLeapYear = ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0));
    boolean thirtyMonth = (month == 9 || month == 4 || month == 5 || month == 10);
    boolean regMonth = (month == 1 || month == 3 || month == 6 || month == 7 || month == 8 || month == 11 || month == 12);

    if ((month <= 0) || (day <= 0) || (day >= 32)) {
        System.out.println("You entered an incorrect month or day value");
    }
    if ((month == 2) && (isLeapYear == true) && (day > 0) && (day <= 29)) {
        System.out.println("it's a leap year - the date is " + date);
        System.exit(0);
    } else if ((month == 2) && (isLeapYear == false) && (day > 0) && (day <= 28)) {
        System.out.println("it's not a leap year - the date is " + date);
        System.exit(0);
    } else if (month == 2) {
        System.out.println("Your input is invald. Non leap-years only have 28 days");
        System.exit(0);
    }

    if ((thirtyMonth == true) && (day > 0) && (day <= 30)) {
        System.out.println("This is a valid date for a 30 day month  - here is the date " + date);
        System.exit(0);
    } else if ((thirtyMonth == true) && (day < 0) || (day >= 31)) {
        System.out.println("Incorrect day input for a regular month with 30 days");
        System.exit(0);
    }

    if ((regMonth) && (day > 0) && (day <= 31)) {
        System.out.println("This is a valid date for a regular month with 31 days - here is the date " + date);
        System.exit(0);
    } else if ((regMonth) && (day < 0) && (day >= 32)) {
        System.out.println("Incorrect day input for a regular month with 31 days");
        System.exit(0);
    }


}

}

Answer 1

4月，6月9月和11月为30天月

boolean thirtyMonth = (month == 9 || month == 4 || month == 5 || month == 10);

应该是

boolean thirtyMonth = (month == 9 || month == 4 || month == 6 || month == 11);
boolean regMonth = (month == 1 || month == 3 || month == 5 ||month == 7 || month == 8 || month == 10 || month == 12);

Answer 2

变化

    } else if ((thirtyMonth == true) && (day < 0) || (day >= 31)) {

到

    } else if (thirtyMonth && (day < 0 || day >= 31)) {

使用Java中的日期验证程序获得不正确的结果

2 个答案: