java 快速排序 ,用nio里的IntBuffer实现,

 1 public class QuickSort {
 2 
 3     static void sort(IntBuffer items, IntBuffer resultItems) {
 4         if (items.capacity() == 1) { // 拆分到只剩1个元素时停止迭代,保存数据到结果队列
 5             resultItems.put(items.get());
 6             return;
 7         }
 8         int midPos = items.capacity() / 2; // 从数组的中间选择一个数进行二分
 9         int midValue = items.get(midPos);
10         IntBuffer lowItems = IntBuffer.allocate(items.capacity());
11         IntBuffer highItems = IntBuffer.allocate(items.capacity());
12         for (int i = 0; i < items.capacity(); i++) {
13             if (i == midPos)
14                 continue;// 跳过自己
15             int curValue = items.get(i);
16             if (curValue <= midValue) {
17                 lowItems.put(curValue);
18             } else {
19                 highItems.put(curValue);
20             }
21         }
22         // 把选的比较数放入较小的集合中,防止死循环
23         if (lowItems.position() < highItems.position())
24             lowItems.put(midValue);
25         else
26             highItems.put(midValue);
27         lowItems.flip();// 截取有效的数据
28         lowItems = lowItems.slice();
29         highItems.flip();
30         highItems = highItems.slice();// 截取有效数据
31         if (lowItems.capacity() > 0) {
32             QuickSort.sort(lowItems, resultItems);
33         }
34         if (highItems.capacity() > 0) {
35             QuickSort.sort(highItems, resultItems);
36         }
37     }
38 
39     public static void main(String[] agrs) {
40         IntBuffer sourceItems = IntBuffer.wrap(new int[] { 5, 2, 10, 1, 3, 8, 5, 6, 1 });
41         IntBuffer resultItems = IntBuffer.allocate(sourceItems.capacity());
42         QuickSort.sort(sourceItems, resultItems);
43         System.out.println(Arrays.toString(resultItems.array()));
44     }
45 }