Java Swing How to - Implement ListModel interface to create custom model








Question

We would like to know how to implement ListModel interface to create custom model.

Answer

/*/* w ww. j a v a2 s  .co m*/
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
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 * modification, are permitted provided that the following conditions
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 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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 * pioneering role in inventing and promulgating (and standardizing) the Java 
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import java.util.ArrayList;
import java.util.Collection;

import javax.swing.ListModel;
import javax.swing.event.ListDataEvent;
import javax.swing.event.ListDataListener;

/**
 * FilterGUIListModel combines an ArrayList with a ListModel for ease of use.
 */
public class FilterGUIListModel extends ArrayList implements ListModel {

  protected Object source;

  FilterGUIListModel(Object src) {
    source = src;
  }

  public Object getElementAt(int index) {
    return get(index);
  }

  public int getSize() {
    return size();
  }

  ArrayList listeners = new ArrayList();

  public void removeListDataListener(javax.swing.event.ListDataListener l) {
    listeners.remove(l);
  }

  public void addListDataListener(javax.swing.event.ListDataListener l) {
    listeners.add(l);
  }

  void notifyListeners() {
    // no attempt at optimziation
    ListDataEvent le = new ListDataEvent(source,
        ListDataEvent.CONTENTS_CHANGED, 0, getSize());
    for (int i = 0; i < listeners.size(); i++) {
      ((ListDataListener) listeners.get(i)).contentsChanged(le);
    }
  }

  // REMAINDER ARE OVERRIDES JUST TO CALL NOTIFYLISTENERS

  public boolean add(Object o) {
    boolean b = super.add(o);
    if (b)
      notifyListeners();
    return b;
  }

  public void add(int index, Object element) {
    super.add(index, element);
    notifyListeners();
  }

  public boolean addAll(Collection o) {
    boolean b = super.add(o);
    if (b)
      notifyListeners();
    return b;
  }

  public void clear() {
    super.clear();
    notifyListeners();
  }

  public Object remove(int i) {
    Object o = super.remove(i);
    notifyListeners();
    return o;
  }

  public boolean remove(Object o) {
    boolean b = super.remove(o);
    if (b)
      notifyListeners();
    return b;
  }

  public Object set(int index, Object element) {
    Object o = super.set(index, element);
    notifyListeners();
    return o;
  }
}