1 /*
   2  * Copyright (c) 1997, 2001, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javax.swing;
  27 
  28 import javax.swing.event.ListDataListener;
  29 
  30 /**
  31  * This interface defines the methods components like JList use
  32  * to get the value of each cell in a list and the length of the list.
  33  * Logically the model is a vector, indices vary from 0 to
  34  * ListDataModel.getSize() - 1.  Any change to the contents or
  35  * length of the data model must be reported to all of the
  36  * ListDataListeners.
  37  *
  38  * @param <E> the type of the elements of this model
  39  *
  40  * @author Hans Muller
  41  * @see JList
  42  */
  43 public interface ListModel<E>
  44 {
  45   /**
  46    * Returns the length of the list.
  47    * @return the length of the list
  48    */
  49   int getSize();
  50 
  51   /**
  52    * Returns the value at the specified index.
  53    * @param index the requested index
  54    * @return the value at <code>index</code>
  55    */
  56   E getElementAt(int index);
  57 
  58   /**
  59    * Adds a listener to the list that's notified each time a change
  60    * to the data model occurs.
  61    * @param l the <code>ListDataListener</code> to be added
  62    */
  63   void addListDataListener(ListDataListener l);
  64 
  65   /**
  66    * Removes a listener from the list that's notified each time a
  67    * change to the data model occurs.
  68    * @param l the <code>ListDataListener</code> to be removed
  69    */
  70   void removeListDataListener(ListDataListener l);
  71 }