1    package javagroup.swing; 
2     
3    import javax.swing.*; 
4     
5    /** 
6     * A combo-box model that keeps a history of items that have been entered 
7     * into the box in the past.  Items are not duplicated, but are moved to 
8     * the top of the list as they are re-entered. 
9     * <p/> 
10    * <p>This class includes an ActionListener inner class that can be 
11    * attached to the combo box to automatically insert entries into the 
12    * history list as they are entered. 
13    * 
14    * @author Martin Pool 
15    * @version $Revision: 1.2 $, $Date: 1999/01/05 11:47:21 $ 
16    */ 
17   public class HistoryComboModel 
18           extends DefaultListModel 
19           implements ComboBoxModel { 
20       /** 
21        * Current selection * 
22        */ 
23       protected Object sel_; 
24    
25       public void setSelectedItem(Object anItem) { 
26           sel_ = anItem; 
27           fireContentsChanged(this, -1, -1); 
28       } 
29    
30       public Object getSelectedItem() { 
31           return sel_; 
32       } 
33    
34       /** 
35        * Add an entry to the top of the history list.  This method should be 
36        * called whenever the application thinks the user has finished adding 
37        * something significant to the combo box: for example, when they press 
38        * the "Ok" button. * 
39        */ 
40       public synchronized void addToHistory(String toAdd) { 
41           // If the string is already present in the history, remove it 
42           for (int i = 0; i < getSize();) { 
43               if (getElementAt(i).equals(toAdd)) 
44                   removeElementAt(i); 
45               else 
46                   i++; 
47           } 
48    
49           // Add to the start of the history 
50           insertElementAt(toAdd, 0); 
51    
52           // In general, everything changed 
53           fireContentsChanged(this, -1, -1); 
54       } 
55   } 
56    
57    
58