ListBox


1   /* 
2    * This file is part of the Echo Web Application Framework (hereinafter "Echo").
3    * Copyright (C) 2002-2005 NextApp, Inc.
4    *
5    * Version: MPL 1.1/GPL 2.0/LGPL 2.1
6    *
7    * The contents of this file are subject to the Mozilla Public License Version
8    * 1.1 (the "License"); you may not use this file except in compliance with
9    * the License. You may obtain a copy of the License at
10   * http://www.mozilla.org/MPL/
11   *
12   * Software distributed under the License is distributed on an "AS IS" basis,
13   * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
14   * for the specific language governing rights and limitations under the
15   * License.
16   *
17   * Alternatively, the contents of this file may be used under the terms of
18   * either the GNU General Public License Version 2 or later (the "GPL"), or
19   * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
20   * in which case the provisions of the GPL or the LGPL are applicable instead
21   * of those above. If you wish to allow use of your version of this file only
22   * under the terms of either the GPL or the LGPL, and not to allow others to
23   * use your version of this file under the terms of the MPL, indicate your
24   * decision by deleting the provisions above and replace them with the notice
25   * and other provisions required by the GPL or the LGPL. If you do not delete
26   * the provisions above, a recipient may use your version of this file under
27   * the terms of any one of the MPL, the GPL or the LGPL.
28   */
29  
30  package nextapp.echo2.app;
31  
32  import nextapp.echo2.app.list.AbstractListComponent;
33  import nextapp.echo2.app.list.DefaultListModel;
34  import nextapp.echo2.app.list.ListModel;
35  import nextapp.echo2.app.list.ListSelectionModel;
36  
37  
38  /**
39   * A component which provides the ability to select one or more items.
40   */
41  public class ListBox extends AbstractListComponent {
42  
43      /**
44       * Creates an empty <code>ListBox</code>.
45       * A <code>DefaultListModel</code> will be created. 
46       * A <code>DefaultListSelectionModel</code> will be created and used
47       * to describe selections.
48       */
49      public ListBox() {
50          super();
51      }
52      
53      /** 
54       * Creates a <code>ListBox</code> visualizing the specified model.
55       * A <code>DefaultListSelectionModel</code> will be created and used
56       * to describe selections.
57       *
58       * @param model the initial model
59       */
60      public ListBox(ListModel model) {
61          super(model, null);
62      }
63      
64      /**
65       * Creates a <code>ListBox</code> visualizing the specified 
66       * <code>ListModel</code> and describing selections using the specified
67       * <code>ListSelectionModel</code>.
68       * 
69       * @param model the initial model
70       * @param selectionModel the initial selection model
71       */
72      public ListBox(ListModel model, ListSelectionModel selectionModel) {
73          super(model, selectionModel);
74      }
75      
76      /**
77       * Creates a <code>ListBox</code> with a <code>DefaultListModel</code>
78       * that initially contains the specified array of items.
79       * A <code>DefaultListSelectionModel</code> will be created and used
80       * to describe selections.
81       *
82       * @param itemArray an array of items that will initially populate
83       *        this <code>ListBox</code>
84       */
85      public ListBox(Object  [] itemArray) {
86          super(new DefaultListModel(itemArray), null);
87      }
88       
89      /**
90       * Returns the maximum selected index.
91       *
92       * @return the maximum selected index
93       */
94      public int getMaxSelectedIndex() {
95          return getSelectionModel().getMaxSelectedIndex();
96      }
97          
98      /**
99       * Returns the minimum selected index.
100      *
101      * @return The minimum selected index
102      */
103     public int getMinSelectedIndex() {
104         return getSelectionModel().getMinSelectedIndex();
105     }
106     
107     /**
108      * Returns all selected indices.
109      *
110      * @return an array containing all the selected indices
111      */
112     public int[] getSelectedIndices() {
113         ListModel model = getModel();
114         int min = getMinSelectedIndex();
115         if (min == -1) {
116             // No indices are selected, return empty array.
117             return new int[0];
118         }
119         
120         int selectionCount = 0;
121         int max = getMaxSelectedIndex();
122         int size = model.size();
123         if (max >= size - 1) {
124             max = size - 1;
125         }
126 
127         for (int index = min; index <= max; ++index) {
128             if (isSelectedIndex(index)) {
129                 ++selectionCount;
130             }
131         }
132 
133         int[] selectedIndices = new int[selectionCount];
134         selectionCount = 0;
135         for (int index = min; index <= max; ++index) {
136             if (isSelectedIndex(index)) {
137                 selectedIndices[selectionCount] = index;
138                 ++selectionCount;
139             }
140         }
141         
142         return selectedIndices;
143     }
144         
145     /**
146      * Returns the selected item.  This method is intended to be used when the
147      * when the selection model is configured to only allow one item to be 
148      * selected at a time.  In the event multiple item selection is enabled, 
149      * this method will return the item at the lowest selected index.
150      *
151      * @return the selected item
152      */
153     public Object   getSelectedValue() {
154         ListModel model = getModel();
155         int selectedIndex = getMinSelectedIndex();
156         Object   value;
157         
158         if (selectedIndex == -1) {
159             value = null;
160         } else {
161             value = model.get(getMinSelectedIndex());
162         }
163 
164         return value;
165     }
166     
167     /**
168      * Returns all selected items.
169      *
170      * @return an array containing all the selected items
171      */
172     public Object  [] getSelectedValues() {
173         ListModel model = getModel();
174         int min = getMinSelectedIndex();
175 
176         if (min == -1) {
177             // No values are selected, return empty array.
178             return new Object  [0];
179         }
180         
181         int selectionCount = 0;
182         int max = getMaxSelectedIndex();
183         int size = model.size();
184         if (max >= size - 1) {
185             max = size - 1;
186         }
187 
188         for (int index = min; index <= max; ++index) {
189             if (isSelectedIndex(index)) {
190                 ++selectionCount;
191             }
192         }
193 
194         Object  [] selectedValues = new Object  [selectionCount];
195         selectionCount = 0;
196         for (int index = min; index <= max; ++index) {
197             if (isSelectedIndex(index)) {
198                 selectedValues[selectionCount] = model.get(index);
199                 ++selectionCount;
200             }
201         }
202         
203         return selectedValues;
204     }
205 
206     /**
207      * Returns the selection mode.
208      * 
209      * @return the selection mode, one of the following values:
210      *         <ul>
211      *          <li><code>ListSelectionModel.SINGLE_SELECTION</code>: only one 
212      *          list element may be selected.</li>
213      *          <li><code>ListSelectionModel.MULTIPLE_SELECTION</code>: 
214      *          multiple list elements may be selected.</li>
215      *         </ul>
216      */
217     public int getSelectionMode() {
218         return getSelectionModel().getSelectionMode();
219     }
220     
221     /**
222      * Determines whether an index is selected.
223      *
224      * @param index the index
225      * @return the selection state of the index
226      */
227     public boolean isSelectedIndex(int index) {
228         return getSelectionModel().isSelectedIndex(index);
229     }
230     
231     /**
232      * Selects only the given index.
233      *
234      * @param index the index
235      */
236     public void setSelectedIndex(int index) {
237         ListSelectionModel selectionModel = getSelectionModel();
238         selectionModel.clearSelection();
239         selectionModel.setSelectedIndex(index, true);    
240     }
241     
242     /**
243      * Sets the selection state of the given index.
244      *
245      * @param index the index
246      * @param selected the selection state
247      */
248     public void setSelectedIndex(int index, boolean selected) {
249         getSelectionModel().setSelectedIndex(index, selected);    
250     }
251     
252     /**
253      * Selects the specified indices, deselecting any other indices.
254      *
255      * @param indices the indices to be selected
256      */
257     public void setSelectedIndices(int[] indices) {
258         ListSelectionModel selectionModel = getSelectionModel();
259         selectionModel.clearSelection();
260         for (int i = 0; i < indices.length; ++i) {
261             selectionModel.setSelectedIndex(indices[i], true);
262         }
263     }
264     
265     /**
266      * Sets the selection mode.  
267      * 
268      * @param newValue the selection mode, one of the following values:
269      *        <ul>
270      *         <li><code>ListSelectionModel.SINGLE_SELECTION</code>: only one 
271      *         list element may be selected.</li>
272      *         <li><code>ListSelectionModel.MULTIPLE_SELECTION</code>: 
273      *         multiple list elements may be selected.</li>
274      *        </ul>
275      */
276     public void setSelectionMode(int newValue) {
277         getSelectionModel().setSelectionMode(newValue);
278     }
279 }
280
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