Quicksort不运行Java

Question

我试图进行快速排序，但它总是显示错误ArrayIndexOutOfBoundsException

public class Quicksort
{
    void sort(int[] arr)
    {
        _quicksort(arr, 0, arr.length - 1);
    }
    private void _quicksort(int[] arr, int left, int right)
    {
        int pivot = (left + right)/2;
        int l = left;
        int r = right;
        while (l <= r)
        {
            while (arr[l] < pivot)
            {
                l++;
            }
            while (arr[r] > pivot)
            {
                r--;
            }
            if(l <= r)
            {
                int temp = l;
                l = r;
                r = temp;
                l++;
                r++;
            }
        }
        if(left < r)
        {
            _quicksort(arr, left, r);
        }
        if(l < right)
        {
            _quicksort(arr, l, right);
        }
    }
}

有人知道它为什么不运行吗？它总是会出错

错误消息是

java.lang.ArrayIndexOutOfBoundsException: -1
    at Quicksort._quicksort(Quicksort.java:18)
    at Quicksort._quicksort(Quicksort.java:33)
    at Quicksort.sort(Quicksort.java:5)

Error Message