1 import java.util.Enumeration;
 2 import java.util.Hashtable;
 3 import java.util.Iterator;
 4 import java.util.Map.Entry;
 5 import java.util.Random;
 6 
 7 /*
 8  * 測試分別通過 Iterator 和 Enumeration 去遍歷Hashtable
 9  * @author skywang
10  */
11 public class IteratorEnumeration {
12 
13     public
 
 static void main(String[] args) {
14         int val;
15         Random r = new Random();
16         Hashtable table = new Hashtable();
17         for (int i=0; i<100000; i++) {
18             // 隨機獲取一個[0,100)之間的數字
19             val = r.nextInt(100);
20             table.put(String.valueOf(i), val);
 
21         }
22 
23         // 通過Iterator遍歷Hashtable
24         iterateHashtable(table) ;
25 
26         // 通過Enumeration遍歷Hashtable
27         enumHashtable(table);
28     }
29     
30     /*
31      * 通過Iterator遍歷Hashtable
32      */
33     private static void iterateHashtable(Hashtable table) {
 
34         long startTime = System.currentTimeMillis();
35 
36         Iterator iter = table.entrySet().iterator();
37         while(iter.hasNext()) {
38             //System.out.println("iter:"+iter.next());
39             iter.next();
40         }
41 
42         long endTime = System.currentTimeMillis();
43         countTime(startTime, endTime);
44     }
45     
46     /*
47      * 通過Enumeration遍歷Hashtable
48      */
49     private static void enumHashtable(Hashtable table) {
50         long startTime = System.currentTimeMillis();
51 
52         Enumeration enu = table.elements();
53         while(enu.hasMoreElements()) {
54             //System.out.println("enu:"+enu.nextElement());
55             enu.nextElement();
56         }
57 
58         long endTime = System.currentTimeMillis();
59         countTime(startTime, endTime);
60     }
61 
62     private static void countTime(long start, long end) {
63         System.out.println("time: "+(end-start)+"ms");
64     }
65 }