Question

对于这个程序，我使用private static void add()方法将用户输入元素放入5个空格数组中。添加这些元素后，用户就可以使用private static void delete()方法，该方法允许他们输入数组中存在的要删除的数字。输入要删除的数字时，除非我尝试删除数组currentSize的最后一个数字，否则程序运行正常。例如，如果我有一个包含以下索引和值的数组：

0. = 1
1. = 2
2. = 3
3. = 4
4. = <empty>

数组的currentSize当前是4.如果我尝试删除索引3中的值4，程序将不会删除值4.如果我尝试在尝试删除值3,2或1后删除值4，这些值也不会删除。另一方面，如果我想首先删除值4以下的任何值，即值1,2和3，程序正常工作，直到我尝试删除索引0中的值4.如果我尝试删除值4在这一点上，没有任何东西被删除。如果我在尝试删除值4后尝试添加值（例如1），则值4将替换为值1.如果我尝试在索引0处删除值4两次然后尝试添加新值，则会得到{ {1}}。我认为这与IndexOutOfBoundsException: -1递减时有关，当currentSize--方法中存在的移除元素算法中没有假设时。{1}}递减。如果有人有这方面的解决方案，将不胜感激，谢谢。该计划发布在下面。我评论了private static void delete()方法给我提出问题的部分。这是我得到的堆栈跟踪：

private static void delete()

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
    at ArrayManager.add(ArrayManager.java:35)
    at ArrayManager.main(ArrayManager.java:216)

/**
 * A class that contains methods to carry out the Add, Update, Delete, Drop, Resize, and End commands to alter the state of an array with 5 integers.
 */
public class ArrayManager
{
    // Array of 5 integers to be modified
    private static int [] values = new int [5];

    private static int currentSize = 0;
    private static int position = 0;
    //private static int index = 0;

    static Scanner in = new Scanner(System.in);

    /**
     * A method that inserts an entered value into the array as long as it is between 1 and 99. If the array is full, an error message will be printed explaining that the array is full.
     */
    private static void add()
    {
        System.out.println("Enter values between 1 and 99, inclusive that you would like to add to the array.");
        if(in.hasNextInt())
        {
            int n = in.nextInt();
            if(n >= 1 && n <= 99)
            {
                if(currentSize < values.length)
                {
                    values[currentSize] = n;
                    currentSize++;
                }
                else
                {
                    System.out.println("ERROR: The array is currently full.");
                }
            }
            else
            {
                System.out.println("ERROR: The number entered must be between 1 and 99, inclusive.");
            }
        }
        else
        {
            System.out.println("ERROR: String has been entered. Enter an Integer.");
        }
    }

/**
     * A method that asks the user to enter a value they wish to delete in the array. The following values are then shifted down in index in the array. If the value chosen does not exist in the array, an error message is displayed explaining that the value entered does not exist in the array.
     */
    private static void delete()
    {
        int n = 0;
        System.out.println("Please enter the value in the array that you wish to remove.");
        if(in.hasNextInt())
        {
            n = in.nextInt();
            for(position = 0; position < values.length; position++)
            {
                if(values[position] == n)
                {
                 // The stack trace points me back to this section of code which removes the specified value in the values array.
                    for(int i = position + 1; i < currentSize; i++)
                    {
                            values[i - 1] = values[i];
                            values[i] = 0;
                    }
                    currentSize--;
                    break;
                }
                else if(position == values.length - 1)
                {
                    System.out.println("ERROR: The value entered does not exist in the array.");
                }
            }
        }
        else
        {
            System.out.println("ERROR: String has been entered. Enter an Integer.");
        }
    }

Answer 1

位置是values数组的最后一个元素的索引的极移情况未得到正确处理。在这种情况下，代码开始迭代下一个索引中的元素，以便将所有元素移位1个位置，并且for循环中的条件不满足条件。

for(int i = position + 1; i < currentSize; i++)

    for(int i = position + 1; i < currentSize; i++)
    {
        values[i - 1] = values[i];
        values[i] = 0;
    }

解决方案是检查该条件并明确处理。

   if(values[position] == n ) {
       if( position != values.length - 1 ) {
           for(int i = position + 1; i < currentSize; i++)
           {
               values[i - 1] = values[i];
               values[i] = 0;
           }
       } else {
           values[i] = 0;
       }
       currentSize--;
       break;
   }

如何删除数组中的最后一个输入元素？

1 个答案: