- /*
- * @(#)CheckboxMenuItem.java 1.40 01/11/29
- *
- * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
- package java.awt;
-
- import java.awt.peer.CheckboxMenuItemPeer;
- import java.awt.event.*;
- import java.io.ObjectOutputStream;
- import java.io.ObjectInputStream;
- import java.io.IOException;
-
-
- /**
- * This class represents a check box that can be included in a menu.
- * Clicking on the check box in the menu changes its state from
- * "on" to "off" or from "off" to "on."
- * <p>
- * The following picture depicts a menu which contains an instance
- * of <code>CheckBoxMenuItem</code>:
- * <p>
- * <img src="doc-files/MenuBar-1.gif"
- * ALIGN=center HSPACE=10 VSPACE=7>
- * <p>
- * The item labeled <code>Check</code> shows a check box menu item
- * in its "off" state.
- * <p>
- * When a check box menu item is selected, AWT sends an item event to
- * the item. Since the event is an instance of <code>ItemEvent</code>,
- * the <code>processEvent</code> method examines the event and passes
- * it along to <code>processItemEvent</code>. The latter method redirects
- * the event to any <code>ItemListener</code> objects that have
- * registered an interest in item events generated by this menu item.
- *
- * @version 1.40, 11/29/01
- * @author Sami Shaio
- * @see java.awt.event.ItemEvent
- * @see java.awt.event.ItemListener
- * @since JDK1.0
- */
- public class CheckboxMenuItem extends MenuItem implements ItemSelectable {
-
- static {
- /* ensure that the necessary native libraries are loaded */
- Toolkit.loadLibraries();
- initIDs();
- }
-
- /*
- * The state of a checkbox menu item
- * @serial
- * @see getState()
- * @see setState()
- */
- boolean state = false;
-
- transient ItemListener itemListener;
-
- private static final String base = "chkmenuitem";
- private static int nameCounter = 0;
-
- /*
- * JDK 1.1 serialVersionUID
- */
- private static final long serialVersionUID = 6190621106981774043L;
-
- /**
- * Create a check box menu item with an empty label.
- * The item's state is initially set to "off."
- * @since JDK1.1
- */
- public CheckboxMenuItem() {
- this("", false);
- }
-
- /**
- * Create a check box menu item with the specified label.
- * The item's state is initially set to "off."
-
- * @param label a string label for the check box menu item,
- * or <code>null</code> for an unlabeled menu item.
- */
- public CheckboxMenuItem(String label) {
- this(label, false);
- }
-
- /**
- * Create a check box menu item with the specified label and state.
- * @param label a string label for the check box menu item,
- * or <code>null</code> for an unlabeled menu item.
- * @param state the initial state of the menu item, where
- * <code>true</code> indicates "on" and
- * <code>false</code> indicates "off."
- * @since JDK1.1
- */
- public CheckboxMenuItem(String label, boolean state) {
- super(label);
- this.state = state;
- }
-
- /**
- * Construct a name for this MenuComponent. Called by getName() when
- * the name is null.
- */
- String constructComponentName() {
- synchronized (getClass()) {
- return base + nameCounter++;
- }
- }
-
- /**
- * Creates the peer of the checkbox item. This peer allows us to
- * change the look of the checkbox item without changing its
- * functionality.
- * Most applications do not call this method directly.
- * @see java.awt.Toolkit#createCheckboxMenuItem(java.awt.CheckboxMenuItem)
- * @see java.awt.Component#getToolkit()
- */
- public void addNotify() {
- synchronized (getTreeLock()) {
- if (peer == null)
- peer = Toolkit.getDefaultToolkit().createCheckboxMenuItem(this);
- super.addNotify();
- }
- }
-
- /**
- * Determines whether the state of this check box menu item
- * is "on" or "off."
- * @return the state of this check box menu item, where
- * <code>true</code> indicates "on" and
- * <code>false</code> indicates "off."
- * @see java.awt.CheckboxMenuItem#setState
- */
- public boolean getState() {
- return state;
- }
-
- /**
- * Sets this check box menu item to the specifed state.
- * The boolean value <code>true</code> indicates "on" while
- * <code>false</code> indicates "off."
- * @param b the boolean state of this
- * check box menu item.
- * @see java.awt.CheckboxMenuItem#getState
- */
- public synchronized void setState(boolean b) {
- state = b;
- CheckboxMenuItemPeer peer = (CheckboxMenuItemPeer)this.peer;
- if (peer != null) {
- peer.setState(b);
- }
- }
-
- /**
- * Returns the an array (length 1) containing the checkbox menu item
- * label or null if the checkbox is not selected.
- * @see ItemSelectable
- */
- public synchronized Object[] getSelectedObjects() {
- if (state) {
- Object[] items = new Object[1];
- items[0] = label;
- return items;
- }
- return null;
- }
-
- /**
- * Adds the specified item listener to receive item events from
- * this check box menu item.
- * If l is null, no exception is thrown and no action is performed.
- *
- * @param l the item listener
- * @see java.awt.event.ItemEvent
- * @see java.awt.event.ItemListener
- * @see java.awt.Choice#removeItemListener
- * @since JDK1.1
- */
- public synchronized void addItemListener(ItemListener l) {
- if (l == null) {
- return;
- }
- itemListener = AWTEventMulticaster.add(itemListener, l);
- newEventsOnly = true;
- }
-
- /**
- * Removes the specified item listener so that it no longer receives
- * item events from this check box menu item.
- * If l is null, no exception is thrown and no action is performed.
- *
- * @param l the item listener
- * @see java.awt.event.ItemEvent
- * @see java.awt.event.ItemListener
- * @see java.awt.Choice#addItemListener
- * @since JDK1.1
- */
- public synchronized void removeItemListener(ItemListener l) {
- if (l == null) {
- return;
- }
- itemListener = AWTEventMulticaster.remove(itemListener, l);
- }
-
- // REMIND: remove when filtering is done at lower level
- boolean eventEnabled(AWTEvent e) {
- if (e.id == ItemEvent.ITEM_STATE_CHANGED) {
- if ((eventMask & AWTEvent.ITEM_EVENT_MASK) != 0 ||
- itemListener != null) {
- return true;
- }
- return false;
- }
- return super.eventEnabled(e);
- }
-
- /**
- * Processes events on this check box menu item.
- * If the event is an instance of <code>ItemEvent</code>,
- * this method invokes the <code>processItemEvent</code> method.
- * If the event is not an item event,
- * it invokes <code>processEvent</code> on the superclass.
- * <p>
- * Check box menu items currently support only item events.
- * @param e the event
- * @see java.awt.event.ItemEvent
- * @see java.awt.CheckboxMenuItem#processItemEvent
- * @since JDK1.1
- */
- protected void processEvent(AWTEvent e) {
- if (e instanceof ItemEvent) {
- processItemEvent((ItemEvent)e);
- return;
- }
- super.processEvent(e);
- }
-
- /**
- * Processes item events occurring on this check box menu item by
- * dispatching them to any registered <code>ItemListener</code> objects.
- * <p>
- * This method is not called unless item events are
- * enabled for this menu item. Item events are enabled
- * when one of the following occurs:
- * <p><ul>
- * <li>An <code>ItemListener</code> object is registered
- * via <code>addItemListener</code>.
- * <li>Item events are enabled via <code>enableEvents</code>.
- * </ul>
- * @param e the item event.
- * @see java.awt.event.ItemEvent
- * @see java.awt.event.ItemListener
- * @see java.awt.CheckboxMenuItem#addItemListener
- * @see java.awt.MenuItem#enableEvents
- * @since JDK1.1
- */
- protected void processItemEvent(ItemEvent e) {
- if (itemListener != null) {
- itemListener.itemStateChanged(e);
- }
- }
-
- /**
- * Returns the parameter string representing the state of this check
- * box menu item. This string is useful for debugging.
- * @return the parameter string of this check box menu item.
- */
- public String paramString() {
- return super.paramString() + ",state=" + state;
- }
-
- /* Serialization support.
- */
-
- /*
- * Serial Data Version
- * @serial
- */
- private int checkboxMenuItemSerializedDataVersion = 1;
-
- /**
- * Writes default serializable fields to stream. Writes
- * a list of serializable ItemListener(s) as optional data.
- * The non-serializable ItemListner(s) are detected and
- * no attempt is made to serialize them.
- *
- * @serialData Null terminated sequence of 0 or more pairs.
- * The pair consists of a String and Object.
- * The String indicates the type of object and
- * is one of the following :
- * itemListenerK indicating and ItemListener object.
- *
- * @see AWTEventMulticaster.save(ObjectOutputStream, String, EventListener)
- * @see java.awt.Component.itemListenerK
- */
- private void writeObject(ObjectOutputStream s)
- throws java.io.IOException
- {
- s.defaultWriteObject();
-
- AWTEventMulticaster.save(s, itemListenerK, itemListener);
- s.writeObject(null);
- }
-
- /*
- * Read the ObjectInputStream and if it isnt null
- * add a listener to receive item events fired
- * by the Checkbox menu item.
- * Unrecognised keys or values will be Ignored.
- * @serial
- * @see removeActionListener()
- * @see addActionListener()
- */
- private void readObject(ObjectInputStream s)
- throws ClassNotFoundException, IOException
- {
- s.defaultReadObject();
-
- Object keyOrNull;
- while(null != (keyOrNull = s.readObject())) {
- String key = ((String)keyOrNull).intern();
-
- if (itemListenerK == key)
- addItemListener((ItemListener)(s.readObject()));
-
- else // skip value for unrecognized key
- s.readObject();
- }
- }
-
- /**
- * Initialize JNI field and method IDs
- */
- private static native void initIDs();
- }