Thu, 01 Nov 2012 04:06:00 GMT

1
2 public class QuickSort {
3     public static int partition(int[] arr, int low, int high){
4         int pivot = arr[low];
5         while(low<high){
6             while(low<high && arr[high]>=pivot){
7                 high--;
8             }
9             if(low<high){
10                 arr[low] = arr[high];
11                 low++;
12             }
13
14             while(low<high && arr[low]<=pivot){
15                 low++;
16             }
17             if(low<high){
18                 arr[high] = arr[low];
19                 high--;
20             }
21         }
22         arr[low] = pivot;
23         return low;
24     }
25
26     public static void sort(int[] arr, int low, int high){
27         int pivot;
28         if(low<high){
29             pivot = partition(arr,low,high);
30             sort(arr,low,pivot-1);
31             sort(arr,pivot+1,high);
32         }
33     }
34
35     public static void quickSort(int[] arr){
36         sort(arr,0,arr.length-1);
37     }
38
39     /*public static void main(String[] args) {
40         int[] arr = {46,34,2,99,6,23,20,8};
41         quickSort(arr);
42         StringBuilder sb = new StringBuilder();
43         for(int i=0;i44             sb.append(arr[i]+",");
45         }
46         sb.deleteCharAt(sb.length()-1);
47         System.out.println(sb);
48     }*/
49 }
50

Wed, 23 Sep 2009 00:39:00 GMT

先看两个��程序：
1�?br />

1public class IntegerTypeTest {
2    public static void main(String[] args){
3        String str = "abc";
4        boolean myBoolean = (str instanceof Integer); //compile time error
5        System.out.println(myBoolean);
6    }
7}

2�?br />

1     import java.util.*;
public class InstanceOfDemo {
2
3    public static void main(String[] args) {
4        System.out.println(new InstanceOfDemo() instanceof String); //compile time error
5        System.out.println(new InstanceOfDemo() instanceof Exception); //compile time error
6        System.out.println(new InstanceOfDemo() instanceof Object); //compilation and output true
7
8        System.out.println(new InstanceOfDemo() instanceof List); //compilation and output false
9    }
10}
11

�q�两个程序的�~�译�l�果和我们预想的不一��P��W�一个程序编译结果是�Q?br />
�W�二个程序编译结果是�Q?br />
产生�q�种错误的原因在于，instanceof�q�算�W�第一个操作数的类型应该是�W�二个操作数的父�c�R��子�c�L��者与�W�二个操作数的类型相同。否则编译会出错�?

晒太�?/a> 2009-09-23 08:39 发表评论

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