快速排序的Java实现

public class QuickSort{    public static int[] quick_sort(int a[], int len) {        if(len == 1 || len == 0) return a;        Random random = new Random();        int k = random.nextInt(len);        int al[] = new int[len];        int ar[] = new int[len];        int len1 = 0, len2 = 0;        for(int i = 0; i < len; ++i) {            if(a[i] <= a[k]) al[len1++] = a[i];            else ar[len2++] = a[i];        }        al = quick_sort(al, len1);        ar = quick_sort(ar, len2);        for(int i = 0; i < len1; ++i) a[i] = al[i];        for(int i = 0; i < len2; ++i) a[len1++] = ar[i];        return a;    }    public static void main(String[] args) {        int a[] = {10, 9, 3, 4, 6, 7, 1};        a = QuickSort.quick_sort(a, a.length);        for(int i = 0; i < a.length; ++i) {            System.out.print(a[i] + " ");        }    }}/*Output1 3 4 6 7 9 10 */