import java.util.Arrays;public class QuickSort {	public static void main(String[] args) {		int[] a = { 34, 1, 99, 44, 89, 42, 31, 6, 3 };		System.out.println(Arrays.toString(a));		quickSort(a, 0, a.length - 1);		System.out.println(Arrays.toString(a));	}	public static void quickSort(int[] arr, int left, int right) {		if (left >= right) {			return;		}		int i = left;		int j = right;		int key = arr[left];		while (i < j) {			while (i < j && arr[j] > key) {// 这两个while不能交换				j--;			}			arr[i] = arr[j];			while (i < j && arr[i] < key) {				i++;			}			arr[j] = arr[i];		}		arr[i] = key;		quickSort(arr, i + 1, right);		quickSort(arr, left, i - 1);	}}