Question

我知道这很简单，但我无法弄清楚为什么我一直得到越界异常。我尝试过以不同的方式初始化数组，但仍然无济于事。我在toString方法中得到异常，并在检查日期是否在其定义的月份的正确范围内的部分。

public class MyDate 
{
//variables for year day and month.
private int year, day, month;

//variable for n which is used to compare to the days for leap years.
int n;

String[] Months = {"January","Feburary","March","April","May","June","July"
                ,"August" ,"September","October","November","December"};
int[] MaxDays = {31,31,31,30,31,30,31,31,30,31,30,31};

public MyDate(int year, int day, int month)
{      
    //Checks to see if the year is valid.
    if (year < 1600 || year > 3000)
    {
        System.out.println("The year entered is not valid, "
                + "You entered: " + year);
        System.out.println("The year must be between 1600 and"
                + " 3000.");
        System.exit(0);
    }
    //Checks to see if the month is valid.
    if (month < 1 || month > 12)
    {
        System.out.println("The month is not valid, " + "You Entered: "
                + month);
        System.out.println("The month must be between 1 and 12.");
        System.exit(0);
    }

    //Checks to see if the day is valid
    if (day >= MaxDays[this.day - 1])
    {
        advance();
    }
    //Checks for a leap year, and if the day is valid or not.
    if ((year %  400 == 0) || (year % 100 != 0))
    {   
           if (year % 4 == 0)
            {
                if (month == 2)
                {   
                    //Loops that goes from 27-31 comparing the day to n.

                    int n = 27;
                    do
                    {
                        if (n == day)
                        {
                            System.out.println("This is a leap year, and you entered " + n + " as the day"
                                    + "\n" + "this day is not valid for a leap year");
                            System.out.println();
                            break;
                        }

                        if (n == 32)
                        {
                            break;
                        }
                        n++;
                    }
                    while (n == day);

                    }
                }
    }
    else    
    {
        this.year=year;
        this.day=day;
        this.month=month;
    }
}

//Checks to see if two dates are equal to eachother.
public boolean equals(Object obj)
{
    if (obj instanceof MyDate){
        MyDate d = (MyDate)obj;
        if (this.getMonth()==d.getMonth() && this.getDay()==d.getDay() &&
            this.getYear()==d.getYear())
            return true;
        else
            return false;
    }
    return false;
}

//gives a general format for the month day and year.
public String toString()
{
    return Months[month - 1] + " " + day + "," + year + "";
}

Answer 1

似乎问题来自那里

if (day >= MaxDays[this.day - 1])

其中this.day = 0

我想你应该通过month。

if (day >= MaxDays[month - 1])

<强>更新
在toString()方法month = 0中，因为您之前没有设置过月份在构造函数中阻止this.month=month;阻止else。

Answer 2

可能错误就在这里，在if condition

中

 if (day >= MaxDays[this.day - 1])

MaxDays []是一个包含12个元素的数组 - 索引0 - 11

days can be from 1-31,所以如果day is greater than 12, it will give an IndexOutOfBoundException.

在你的代码中虽然它总是为零，因为你在使用它之前没有初始化它。

ArrayIndexOutOfBoundsException异常？

2 个答案: