快速排序java代码

public class QuickSort {

public static void quickSort(int[] arr, int begin, int end) {
    if (begin < end) {
        int partitionIndex = partition(arr, begin, end);
        quickSort(arr, begin, partitionIndex - 1);
        quickSort(arr, partitionIndex + 1, end);
    }
}

private static int partition(int[] arr, int begin, int end) {
    int pivot = arr[end];
    int i = (begin - 1);
    for (int j = begin; j < end; j++) {
        if (arr[j] <= pivot) {
            i++;
            int swapTemp = arr[i];
            arr[i] = arr[j];
            arr[j] = swapTemp;
        }
    }
    int swapTemp = arr[i + 1];
    arr[i + 1] = arr[end];
    arr[end] = swapTemp;
    return i + 1;
}

public static void main(String[] args) {
    int[] arr = {5, 2, 9, 3, 6, 7, 1, 8, 4};
    quickSort(arr, 0, arr.length - 1);
    System.out.println(Arrays.toString(arr));
}

}