1    package gui.browser; 
2     
3    import java.net.MalformedURLException; 
4    import java.net.URL; 
5    import java.util.Vector; 
6     
7     
8    /** 
9     * LinkQueue 
10    * Features: 
11    *      1. A way to go back to the previous link. 
12    *      2. A way to go forward to the next visited link. 
13    */ 
14    
15   public class LinkQueue { 
16       private Vector v = new Vector(); 
17       private int i = 0; 
18       BrowserLogic bl; 
19    
20       public LinkQueue() { 
21           try { 
22               v.addElement(new URL("http://lyon.fairfield.edu")); 
23           } catch (MalformedURLException e) { 
24               e.printStackTrace(); 
25           } 
26       } 
27    
28       public void enQueue(URL u) { 
29           i++; 
30           v.add(i, u); 
31           System.out.println("en i = " + i + v.elementAt(i)); 
32    
33       } 
34    
35       public URL next() { 
36           i++; 
37           if (i >= v.size()) i = 0; 
38           System.out.println("next i = " + i + v.elementAt(i)); 
39           return (URL) v.elementAt(i); 
40    
41       } 
42    
43       public URL previous() { 
44           i--; 
45           if (i < 0) i = v.size() - 1; 
46           System.out.println("prev i = " + i + v.elementAt(i)); 
47           return (URL) v.elementAt(i); 
48    
49       } 
50    
51       public String toString() { 
52           String s = ""; 
53           for (int j = 0; j < 10; j++) 
54               s = s + (next()).toString() + "\n"; 
55           return s; 
56       } 
57    
58       public static void main(String args[]) throws 
59               MalformedURLException { 
60           LinkQueue lq = new LinkQueue(); 
61   //     System.out.println(lq); 
62       } 
63   } 
64