写一个java的快排

public class QuickSort {

public void sort(int[] arr) {
    quickSort(arr, 0, arr.length-1);
}

private void quickSort(int[] arr, int low, int high) {
    if (low < high) {
        int pivotPos = partition(arr, low, high);
        quickSort(arr, low, pivotPos-1);
        quickSort(arr, pivotPos+1, high);
    }
}

private int partition(int[] arr, int low, int high) {
    int pivot = arr[low];
    while (low < high) {
        while (low < high && arr[high] >= pivot) {
            high--;
        }
        arr[low] = arr[high];
        while (low < high && arr[low] <= pivot) {
            low++;
        }
        arr[high] = arr[low];
    }
    arr[low] = pivot;
    return low;
}

}