1/*
2 * Copyright (c) 2000, 2014, 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
26package javax.swing;
27
28import java.util.*;
29import javax.swing.event.*;
30import java.io.Serializable;
31
32
33/**
34 * This class provides the ChangeListener part of the
35 * SpinnerModel interface that should be suitable for most concrete SpinnerModel
36 * implementations.  Subclasses must provide an implementation of the
37 * <code>setValue</code>, <code>getValue</code>, <code>getNextValue</code> and
38 * <code>getPreviousValue</code> methods.
39 *
40 * @see JSpinner
41 * @see SpinnerModel
42 * @see SpinnerListModel
43 * @see SpinnerNumberModel
44 * @see SpinnerDateModel
45 *
46 * @author Hans Muller
47 * @since 1.4
48 */
49@SuppressWarnings("serial") // Field contents are not serializable across versions
50public abstract class AbstractSpinnerModel implements SpinnerModel, Serializable
51{
52
53    /**
54     * Only one ChangeEvent is needed per model instance since the
55     * event's only (read-only) state is the source property.  The source
56     * of events generated here is always "this".
57     */
58    private transient ChangeEvent changeEvent = null;
59
60
61    /**
62     * The list of ChangeListeners for this model.  Subclasses may
63     * store their own listeners here.
64     */
65    protected EventListenerList listenerList = new EventListenerList();
66
67
68    /**
69     * Adds a ChangeListener to the model's listener list.  The
70     * ChangeListeners must be notified when the models value changes.
71     *
72     * @param l the ChangeListener to add
73     * @see #removeChangeListener
74     * @see SpinnerModel#addChangeListener
75     */
76    public void addChangeListener(ChangeListener l) {
77        listenerList.add(ChangeListener.class, l);
78    }
79
80
81    /**
82     * Removes a ChangeListener from the model's listener list.
83     *
84     * @param l the ChangeListener to remove
85     * @see #addChangeListener
86     * @see SpinnerModel#removeChangeListener
87     */
88    public void removeChangeListener(ChangeListener l) {
89        listenerList.remove(ChangeListener.class, l);
90    }
91
92
93    /**
94     * Returns an array of all the <code>ChangeListener</code>s added
95     * to this AbstractSpinnerModel with addChangeListener().
96     *
97     * @return all of the <code>ChangeListener</code>s added or an empty
98     *         array if no listeners have been added
99     * @since 1.4
100     */
101    public ChangeListener[] getChangeListeners() {
102        return listenerList.getListeners(ChangeListener.class);
103    }
104
105
106    /**
107     * Run each ChangeListeners stateChanged() method.
108     *
109     * @see #setValue
110     * @see EventListenerList
111     */
112    protected void fireStateChanged()
113    {
114        Object[] listeners = listenerList.getListenerList();
115        for (int i = listeners.length - 2; i >= 0; i -=2 ) {
116            if (listeners[i] == ChangeListener.class) {
117                if (changeEvent == null) {
118                    changeEvent = new ChangeEvent(this);
119                }
120                ((ChangeListener)listeners[i+1]).stateChanged(changeEvent);
121            }
122        }
123    }
124
125
126    /**
127     * Return an array of all the listeners of the given type that
128     * were added to this model.  For example to find all of the
129     * ChangeListeners added to this model:
130     * <pre>
131     * myAbstractSpinnerModel.getListeners(ChangeListener.class);
132     * </pre>
133     *
134     * @param <T> the type of requested listeners
135     * @param listenerType the type of listeners to return, e.g. ChangeListener.class
136     * @return all of the objects receiving <em>listenerType</em> notifications
137     *         from this model
138     */
139    public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
140        return listenerList.getListeners(listenerType);
141    }
142}
143