java - 我的递归方法无法正确返回 char 出现的总数

Question

{
    char[] charArray = {'a', 'b', 'a', 'c', 'a', 'd', 'e', 'b'};
    int occurrences;

    occurrences = countOccurrence(charArray, 'a', 0);

    System.out.println("\"a\" occurred " + occurrences + " times.");
} 
public static int countOccurrence(char[] array, char character, int index)
{
    int counter = 0;
    if (index > array.length-1)
    {
        //This probably seems a little awkward...But I have this here just so it stops 
        //recursion when it hits the end of the array.
    }
    else
    {
        if (array[index] == character)
        {
            counter++;
            countOccurrence(array, character, index + 1);
        }
        else
        {
            countOccurrence(array, character, index + 1);
        }            
    }
    return counter;
}

嗨，由于某种原因，当我运行这个程序时，“a”出现的次数始终是 1...我尝试过以各种方式调整它，但我已经没有想法了。我在递归方面还是个新手。

Answer 1

您应该坚持使用简单的for循环，而不是困惑的递归。

public static int countOccurrence(char[] array, char character)
{
    int counter = 0;
    for(int index = 0; index < array.length; ++index)
    {
        if (array[index] == character)
        {
            counter++;
        }
    }
    return counter;
}

或者，如果您一心想使用递归:

当您的index达到值array.length时，只需终止递归即可。

也就是说，

public static int countOccurrence(char[] array, char character, int index)
{
    int counter = 0;
    if (index >= array.length)
        return 0;
    if (array[index] == character)
            counter++;
    counter += countOccurrence(array, character, index + 1);
    return counter;
}