Java example source code file (AWTEventMulticaster.java)
The AWTEventMulticaster.java Java example source code/*
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package java.awt;
import java.awt.event.*;
import java.lang.reflect.Array;
import java.util.EventListener;
import java.io.Serializable;
import java.io.ObjectOutputStream;
import java.io.IOException;
import java.util.EventListener;
/**
* {@code AWTEventMulticaster} implements efficient and thread-safe multi-cast
* event dispatching for the AWT events defined in the {@code java.awt.event}
* package.
* <p>
* The following example illustrates how to use this class:
*
* <pre>
* The important point to note is the first argument to the {@code
* add} and {@code remove} methods is the field maintaining the
* listeners. In addition you must assign the result of the {@code add}
* and {@code remove} methods to the field maintaining the listeners.
* <p>
* {@code AWTEventMulticaster} is implemented as a pair of {@code
* EventListeners} that are set at construction time. {@code
* AWTEventMulticaster} is immutable. The {@code add} and {@code
* remove} methods do not alter {@code AWTEventMulticaster} in
* anyway. If necessary, a new {@code AWTEventMulticaster} is
* created. In this way it is safe to add and remove listeners during
* the process of an event dispatching. However, event listeners
* added during the process of an event dispatch operation are not
* notified of the event currently being dispatched.
* <p>
* All of the {@code add} methods allow {@code null} arguments. If the
* first argument is {@code null}, the second argument is returned. If
* the first argument is not {@code null} and the second argument is
* {@code null}, the first argument is returned. If both arguments are
* {@code non-null}, a new {@code AWTEventMulticaster} is created using
* the two arguments and returned.
* <p>
* For the {@code remove} methods that take two arguments, the following is
* returned:
* <ul>
* <li>{@code null}, if the first argument is {@code null}, or
* the arguments are equal, by way of {@code ==}.
* <li>the first argument, if the first argument is not an instance of
* {@code AWTEventMulticaster}.
* <li>result of invoking {@code remove(EventListener)} on the
* first argument, supplying the second argument to the
* {@code remove(EventListener)} method.
* </ul>
* <p>Swing makes use of
* {@link javax.swing.event.EventListenerList EventListenerList} for
* similar logic. Refer to it for details.
*
* @see javax.swing.event.EventListenerList
*
* @author John Rose
* @author Amy Fowler
* @since 1.1
*/
public class AWTEventMulticaster implements
ComponentListener, ContainerListener, FocusListener, KeyListener,
MouseListener, MouseMotionListener, WindowListener, WindowFocusListener,
WindowStateListener, ActionListener, ItemListener, AdjustmentListener,
TextListener, InputMethodListener, HierarchyListener,
HierarchyBoundsListener, MouseWheelListener {
protected final EventListener a, b;
/**
* Creates an event multicaster instance which chains listener-a
* with listener-b. Input parameters <code>a and b
* should not be <code>null, though implementations may vary in
* choosing whether or not to throw <code>NullPointerException
* in that case.
* @param a listener-a
* @param b listener-b
*/
protected AWTEventMulticaster(EventListener a, EventListener b) {
this.a = a; this.b = b;
}
/**
* Removes a listener from this multicaster.
* <p>
* The returned multicaster contains all the listeners in this
* multicaster with the exception of all occurrences of {@code oldl}.
* If the resulting multicaster contains only one regular listener
* the regular listener may be returned. If the resulting multicaster
* is empty, then {@code null} may be returned instead.
* <p>
* No exception is thrown if {@code oldl} is {@code null}.
*
* @param oldl the listener to be removed
* @return resulting listener
*/
protected EventListener remove(EventListener oldl) {
if (oldl == a) return b;
if (oldl == b) return a;
EventListener a2 = removeInternal(a, oldl);
EventListener b2 = removeInternal(b, oldl);
if (a2 == a && b2 == b) {
return this; // it's not here
}
return addInternal(a2, b2);
}
/**
* Handles the componentResized event by invoking the
* componentResized methods on listener-a and listener-b.
* @param e the component event
*/
public void componentResized(ComponentEvent e) {
((ComponentListener)a).componentResized(e);
((ComponentListener)b).componentResized(e);
}
/**
* Handles the componentMoved event by invoking the
* componentMoved methods on listener-a and listener-b.
* @param e the component event
*/
public void componentMoved(ComponentEvent e) {
((ComponentListener)a).componentMoved(e);
((ComponentListener)b).componentMoved(e);
}
/**
* Handles the componentShown event by invoking the
* componentShown methods on listener-a and listener-b.
* @param e the component event
*/
public void componentShown(ComponentEvent e) {
((ComponentListener)a).componentShown(e);
((ComponentListener)b).componentShown(e);
}
/**
* Handles the componentHidden event by invoking the
* componentHidden methods on listener-a and listener-b.
* @param e the component event
*/
public void componentHidden(ComponentEvent e) {
((ComponentListener)a).componentHidden(e);
((ComponentListener)b).componentHidden(e);
}
/**
* Handles the componentAdded container event by invoking the
* componentAdded methods on listener-a and listener-b.
* @param e the component event
*/
public void componentAdded(ContainerEvent e) {
((ContainerListener)a).componentAdded(e);
((ContainerListener)b).componentAdded(e);
}
/**
* Handles the componentRemoved container event by invoking the
* componentRemoved methods on listener-a and listener-b.
* @param e the component event
*/
public void componentRemoved(ContainerEvent e) {
((ContainerListener)a).componentRemoved(e);
((ContainerListener)b).componentRemoved(e);
}
/**
* Handles the focusGained event by invoking the
* focusGained methods on listener-a and listener-b.
* @param e the focus event
*/
public void focusGained(FocusEvent e) {
((FocusListener)a).focusGained(e);
((FocusListener)b).focusGained(e);
}
/**
* Handles the focusLost event by invoking the
* focusLost methods on listener-a and listener-b.
* @param e the focus event
*/
public void focusLost(FocusEvent e) {
((FocusListener)a).focusLost(e);
((FocusListener)b).focusLost(e);
}
/**
* Handles the keyTyped event by invoking the
* keyTyped methods on listener-a and listener-b.
* @param e the key event
*/
public void keyTyped(KeyEvent e) {
((KeyListener)a).keyTyped(e);
((KeyListener)b).keyTyped(e);
}
/**
* Handles the keyPressed event by invoking the
* keyPressed methods on listener-a and listener-b.
* @param e the key event
*/
public void keyPressed(KeyEvent e) {
((KeyListener)a).keyPressed(e);
((KeyListener)b).keyPressed(e);
}
/**
* Handles the keyReleased event by invoking the
* keyReleased methods on listener-a and listener-b.
* @param e the key event
*/
public void keyReleased(KeyEvent e) {
((KeyListener)a).keyReleased(e);
((KeyListener)b).keyReleased(e);
}
/**
* Handles the mouseClicked event by invoking the
* mouseClicked methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mouseClicked(MouseEvent e) {
((MouseListener)a).mouseClicked(e);
((MouseListener)b).mouseClicked(e);
}
/**
* Handles the mousePressed event by invoking the
* mousePressed methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mousePressed(MouseEvent e) {
((MouseListener)a).mousePressed(e);
((MouseListener)b).mousePressed(e);
}
/**
* Handles the mouseReleased event by invoking the
* mouseReleased methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mouseReleased(MouseEvent e) {
((MouseListener)a).mouseReleased(e);
((MouseListener)b).mouseReleased(e);
}
/**
* Handles the mouseEntered event by invoking the
* mouseEntered methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mouseEntered(MouseEvent e) {
((MouseListener)a).mouseEntered(e);
((MouseListener)b).mouseEntered(e);
}
/**
* Handles the mouseExited event by invoking the
* mouseExited methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mouseExited(MouseEvent e) {
((MouseListener)a).mouseExited(e);
((MouseListener)b).mouseExited(e);
}
/**
* Handles the mouseDragged event by invoking the
* mouseDragged methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mouseDragged(MouseEvent e) {
((MouseMotionListener)a).mouseDragged(e);
((MouseMotionListener)b).mouseDragged(e);
}
/**
* Handles the mouseMoved event by invoking the
* mouseMoved methods on listener-a and listener-b.
* @param e the mouse event
*/
public void mouseMoved(MouseEvent e) {
((MouseMotionListener)a).mouseMoved(e);
((MouseMotionListener)b).mouseMoved(e);
}
/**
* Handles the windowOpened event by invoking the
* windowOpened methods on listener-a and listener-b.
* @param e the window event
*/
public void windowOpened(WindowEvent e) {
((WindowListener)a).windowOpened(e);
((WindowListener)b).windowOpened(e);
}
/**
* Handles the windowClosing event by invoking the
* windowClosing methods on listener-a and listener-b.
* @param e the window event
*/
public void windowClosing(WindowEvent e) {
((WindowListener)a).windowClosing(e);
((WindowListener)b).windowClosing(e);
}
/**
* Handles the windowClosed event by invoking the
* windowClosed methods on listener-a and listener-b.
* @param e the window event
*/
public void windowClosed(WindowEvent e) {
((WindowListener)a).windowClosed(e);
((WindowListener)b).windowClosed(e);
}
/**
* Handles the windowIconified event by invoking the
* windowIconified methods on listener-a and listener-b.
* @param e the window event
*/
public void windowIconified(WindowEvent e) {
((WindowListener)a).windowIconified(e);
((WindowListener)b).windowIconified(e);
}
/**
* Handles the windowDeiconfied event by invoking the
* windowDeiconified methods on listener-a and listener-b.
* @param e the window event
*/
public void windowDeiconified(WindowEvent e) {
((WindowListener)a).windowDeiconified(e);
((WindowListener)b).windowDeiconified(e);
}
/**
* Handles the windowActivated event by invoking the
* windowActivated methods on listener-a and listener-b.
* @param e the window event
*/
public void windowActivated(WindowEvent e) {
((WindowListener)a).windowActivated(e);
((WindowListener)b).windowActivated(e);
}
/**
* Handles the windowDeactivated event by invoking the
* windowDeactivated methods on listener-a and listener-b.
* @param e the window event
*/
public void windowDeactivated(WindowEvent e) {
((WindowListener)a).windowDeactivated(e);
((WindowListener)b).windowDeactivated(e);
}
/**
* Handles the windowStateChanged event by invoking the
* windowStateChanged methods on listener-a and listener-b.
* @param e the window event
* @since 1.4
*/
public void windowStateChanged(WindowEvent e) {
((WindowStateListener)a).windowStateChanged(e);
((WindowStateListener)b).windowStateChanged(e);
}
/**
* Handles the windowGainedFocus event by invoking the windowGainedFocus
* methods on listener-a and listener-b.
* @param e the window event
* @since 1.4
*/
public void windowGainedFocus(WindowEvent e) {
((WindowFocusListener)a).windowGainedFocus(e);
((WindowFocusListener)b).windowGainedFocus(e);
}
/**
* Handles the windowLostFocus event by invoking the windowLostFocus
* methods on listener-a and listener-b.
* @param e the window event
* @since 1.4
*/
public void windowLostFocus(WindowEvent e) {
((WindowFocusListener)a).windowLostFocus(e);
((WindowFocusListener)b).windowLostFocus(e);
}
/**
* Handles the actionPerformed event by invoking the
* actionPerformed methods on listener-a and listener-b.
* @param e the action event
*/
public void actionPerformed(ActionEvent e) {
((ActionListener)a).actionPerformed(e);
((ActionListener)b).actionPerformed(e);
}
/**
* Handles the itemStateChanged event by invoking the
* itemStateChanged methods on listener-a and listener-b.
* @param e the item event
*/
public void itemStateChanged(ItemEvent e) {
((ItemListener)a).itemStateChanged(e);
((ItemListener)b).itemStateChanged(e);
}
/**
* Handles the adjustmentValueChanged event by invoking the
* adjustmentValueChanged methods on listener-a and listener-b.
* @param e the adjustment event
*/
public void adjustmentValueChanged(AdjustmentEvent e) {
((AdjustmentListener)a).adjustmentValueChanged(e);
((AdjustmentListener)b).adjustmentValueChanged(e);
}
public void textValueChanged(TextEvent e) {
((TextListener)a).textValueChanged(e);
((TextListener)b).textValueChanged(e);
}
/**
* Handles the inputMethodTextChanged event by invoking the
* inputMethodTextChanged methods on listener-a and listener-b.
* @param e the item event
*/
public void inputMethodTextChanged(InputMethodEvent e) {
((InputMethodListener)a).inputMethodTextChanged(e);
((InputMethodListener)b).inputMethodTextChanged(e);
}
/**
* Handles the caretPositionChanged event by invoking the
* caretPositionChanged methods on listener-a and listener-b.
* @param e the item event
*/
public void caretPositionChanged(InputMethodEvent e) {
((InputMethodListener)a).caretPositionChanged(e);
((InputMethodListener)b).caretPositionChanged(e);
}
/**
* Handles the hierarchyChanged event by invoking the
* hierarchyChanged methods on listener-a and listener-b.
* @param e the item event
* @since 1.3
*/
public void hierarchyChanged(HierarchyEvent e) {
((HierarchyListener)a).hierarchyChanged(e);
((HierarchyListener)b).hierarchyChanged(e);
}
/**
* Handles the ancestorMoved event by invoking the
* ancestorMoved methods on listener-a and listener-b.
* @param e the item event
* @since 1.3
*/
public void ancestorMoved(HierarchyEvent e) {
((HierarchyBoundsListener)a).ancestorMoved(e);
((HierarchyBoundsListener)b).ancestorMoved(e);
}
/**
* Handles the ancestorResized event by invoking the
* ancestorResized methods on listener-a and listener-b.
* @param e the item event
* @since 1.3
*/
public void ancestorResized(HierarchyEvent e) {
((HierarchyBoundsListener)a).ancestorResized(e);
((HierarchyBoundsListener)b).ancestorResized(e);
}
/**
* Handles the mouseWheelMoved event by invoking the
* mouseWheelMoved methods on listener-a and listener-b.
* @param e the mouse event
* @since 1.4
*/
public void mouseWheelMoved(MouseWheelEvent e) {
((MouseWheelListener)a).mouseWheelMoved(e);
((MouseWheelListener)b).mouseWheelMoved(e);
}
/**
* Adds component-listener-a with component-listener-b and
* returns the resulting multicast listener.
* @param a component-listener-a
* @param b component-listener-b
*/
public static ComponentListener add(ComponentListener a, ComponentListener b) {
return (ComponentListener)addInternal(a, b);
}
/**
* Adds container-listener-a with container-listener-b and
* returns the resulting multicast listener.
* @param a container-listener-a
* @param b container-listener-b
*/
public static ContainerListener add(ContainerListener a, ContainerListener b) {
return (ContainerListener)addInternal(a, b);
}
/**
* Adds focus-listener-a with focus-listener-b and
* returns the resulting multicast listener.
* @param a focus-listener-a
* @param b focus-listener-b
*/
public static FocusListener add(FocusListener a, FocusListener b) {
return (FocusListener)addInternal(a, b);
}
/**
* Adds key-listener-a with key-listener-b and
* returns the resulting multicast listener.
* @param a key-listener-a
* @param b key-listener-b
*/
public static KeyListener add(KeyListener a, KeyListener b) {
return (KeyListener)addInternal(a, b);
}
/**
* Adds mouse-listener-a with mouse-listener-b and
* returns the resulting multicast listener.
* @param a mouse-listener-a
* @param b mouse-listener-b
*/
public static MouseListener add(MouseListener a, MouseListener b) {
return (MouseListener)addInternal(a, b);
}
/**
* Adds mouse-motion-listener-a with mouse-motion-listener-b and
* returns the resulting multicast listener.
* @param a mouse-motion-listener-a
* @param b mouse-motion-listener-b
*/
public static MouseMotionListener add(MouseMotionListener a, MouseMotionListener b) {
return (MouseMotionListener)addInternal(a, b);
}
/**
* Adds window-listener-a with window-listener-b and
* returns the resulting multicast listener.
* @param a window-listener-a
* @param b window-listener-b
*/
public static WindowListener add(WindowListener a, WindowListener b) {
return (WindowListener)addInternal(a, b);
}
/**
* Adds window-state-listener-a with window-state-listener-b
* and returns the resulting multicast listener.
* @param a window-state-listener-a
* @param b window-state-listener-b
* @since 1.4
*/
public static WindowStateListener add(WindowStateListener a,
WindowStateListener b) {
return (WindowStateListener)addInternal(a, b);
}
/**
* Adds window-focus-listener-a with window-focus-listener-b
* and returns the resulting multicast listener.
* @param a window-focus-listener-a
* @param b window-focus-listener-b
* @since 1.4
*/
public static WindowFocusListener add(WindowFocusListener a,
WindowFocusListener b) {
return (WindowFocusListener)addInternal(a, b);
}
/**
* Adds action-listener-a with action-listener-b and
* returns the resulting multicast listener.
* @param a action-listener-a
* @param b action-listener-b
*/
public static ActionListener add(ActionListener a, ActionListener b) {
return (ActionListener)addInternal(a, b);
}
/**
* Adds item-listener-a with item-listener-b and
* returns the resulting multicast listener.
* @param a item-listener-a
* @param b item-listener-b
*/
public static ItemListener add(ItemListener a, ItemListener b) {
return (ItemListener)addInternal(a, b);
}
/**
* Adds adjustment-listener-a with adjustment-listener-b and
* returns the resulting multicast listener.
* @param a adjustment-listener-a
* @param b adjustment-listener-b
*/
public static AdjustmentListener add(AdjustmentListener a, AdjustmentListener b) {
return (AdjustmentListener)addInternal(a, b);
}
public static TextListener add(TextListener a, TextListener b) {
return (TextListener)addInternal(a, b);
}
/**
* Adds input-method-listener-a with input-method-listener-b and
* returns the resulting multicast listener.
* @param a input-method-listener-a
* @param b input-method-listener-b
*/
public static InputMethodListener add(InputMethodListener a, InputMethodListener b) {
return (InputMethodListener)addInternal(a, b);
}
/**
* Adds hierarchy-listener-a with hierarchy-listener-b and
* returns the resulting multicast listener.
* @param a hierarchy-listener-a
* @param b hierarchy-listener-b
* @since 1.3
*/
public static HierarchyListener add(HierarchyListener a, HierarchyListener b) {
return (HierarchyListener)addInternal(a, b);
}
/**
* Adds hierarchy-bounds-listener-a with hierarchy-bounds-listener-b and
* returns the resulting multicast listener.
* @param a hierarchy-bounds-listener-a
* @param b hierarchy-bounds-listener-b
* @since 1.3
*/
public static HierarchyBoundsListener add(HierarchyBoundsListener a, HierarchyBoundsListener b) {
return (HierarchyBoundsListener)addInternal(a, b);
}
/**
* Adds mouse-wheel-listener-a with mouse-wheel-listener-b and
* returns the resulting multicast listener.
* @param a mouse-wheel-listener-a
* @param b mouse-wheel-listener-b
* @since 1.4
*/
public static MouseWheelListener add(MouseWheelListener a,
MouseWheelListener b) {
return (MouseWheelListener)addInternal(a, b);
}
/**
* Removes the old component-listener from component-listener-l and
* returns the resulting multicast listener.
* @param l component-listener-l
* @param oldl the component-listener being removed
*/
public static ComponentListener remove(ComponentListener l, ComponentListener oldl) {
return (ComponentListener) removeInternal(l, oldl);
}
/**
* Removes the old container-listener from container-listener-l and
* returns the resulting multicast listener.
* @param l container-listener-l
* @param oldl the container-listener being removed
*/
public static ContainerListener remove(ContainerListener l, ContainerListener oldl) {
return (ContainerListener) removeInternal(l, oldl);
}
/**
* Removes the old focus-listener from focus-listener-l and
* returns the resulting multicast listener.
* @param l focus-listener-l
* @param oldl the focus-listener being removed
*/
public static FocusListener remove(FocusListener l, FocusListener oldl) {
return (FocusListener) removeInternal(l, oldl);
}
/**
* Removes the old key-listener from key-listener-l and
* returns the resulting multicast listener.
* @param l key-listener-l
* @param oldl the key-listener being removed
*/
public static KeyListener remove(KeyListener l, KeyListener oldl) {
return (KeyListener) removeInternal(l, oldl);
}
/**
* Removes the old mouse-listener from mouse-listener-l and
* returns the resulting multicast listener.
* @param l mouse-listener-l
* @param oldl the mouse-listener being removed
*/
public static MouseListener remove(MouseListener l, MouseListener oldl) {
return (MouseListener) removeInternal(l, oldl);
}
/**
* Removes the old mouse-motion-listener from mouse-motion-listener-l
* and returns the resulting multicast listener.
* @param l mouse-motion-listener-l
* @param oldl the mouse-motion-listener being removed
*/
public static MouseMotionListener remove(MouseMotionListener l, MouseMotionListener oldl) {
return (MouseMotionListener) removeInternal(l, oldl);
}
/**
* Removes the old window-listener from window-listener-l and
* returns the resulting multicast listener.
* @param l window-listener-l
* @param oldl the window-listener being removed
*/
public static WindowListener remove(WindowListener l, WindowListener oldl) {
return (WindowListener) removeInternal(l, oldl);
}
/**
* Removes the old window-state-listener from window-state-listener-l
* and returns the resulting multicast listener.
* @param l window-state-listener-l
* @param oldl the window-state-listener being removed
* @since 1.4
*/
public static WindowStateListener remove(WindowStateListener l,
WindowStateListener oldl) {
return (WindowStateListener) removeInternal(l, oldl);
}
/**
* Removes the old window-focus-listener from window-focus-listener-l
* and returns the resulting multicast listener.
* @param l window-focus-listener-l
* @param oldl the window-focus-listener being removed
* @since 1.4
*/
public static WindowFocusListener remove(WindowFocusListener l,
WindowFocusListener oldl) {
return (WindowFocusListener) removeInternal(l, oldl);
}
/**
* Removes the old action-listener from action-listener-l and
* returns the resulting multicast listener.
* @param l action-listener-l
* @param oldl the action-listener being removed
*/
public static ActionListener remove(ActionListener l, ActionListener oldl) {
return (ActionListener) removeInternal(l, oldl);
}
/**
* Removes the old item-listener from item-listener-l and
* returns the resulting multicast listener.
* @param l item-listener-l
* @param oldl the item-listener being removed
*/
public static ItemListener remove(ItemListener l, ItemListener oldl) {
return (ItemListener) removeInternal(l, oldl);
}
/**
* Removes the old adjustment-listener from adjustment-listener-l and
* returns the resulting multicast listener.
* @param l adjustment-listener-l
* @param oldl the adjustment-listener being removed
*/
public static AdjustmentListener remove(AdjustmentListener l, AdjustmentListener oldl) {
return (AdjustmentListener) removeInternal(l, oldl);
}
public static TextListener remove(TextListener l, TextListener oldl) {
return (TextListener) removeInternal(l, oldl);
}
/**
* Removes the old input-method-listener from input-method-listener-l and
* returns the resulting multicast listener.
* @param l input-method-listener-l
* @param oldl the input-method-listener being removed
*/
public static InputMethodListener remove(InputMethodListener l, InputMethodListener oldl) {
return (InputMethodListener) removeInternal(l, oldl);
}
/**
* Removes the old hierarchy-listener from hierarchy-listener-l and
* returns the resulting multicast listener.
* @param l hierarchy-listener-l
* @param oldl the hierarchy-listener being removed
* @since 1.3
*/
public static HierarchyListener remove(HierarchyListener l, HierarchyListener oldl) {
return (HierarchyListener) removeInternal(l, oldl);
}
/**
* Removes the old hierarchy-bounds-listener from
* hierarchy-bounds-listener-l and returns the resulting multicast
* listener.
* @param l hierarchy-bounds-listener-l
* @param oldl the hierarchy-bounds-listener being removed
* @since 1.3
*/
public static HierarchyBoundsListener remove(HierarchyBoundsListener l, HierarchyBoundsListener oldl) {
return (HierarchyBoundsListener) removeInternal(l, oldl);
}
/**
* Removes the old mouse-wheel-listener from mouse-wheel-listener-l
* and returns the resulting multicast listener.
* @param l mouse-wheel-listener-l
* @param oldl the mouse-wheel-listener being removed
* @since 1.4
*/
public static MouseWheelListener remove(MouseWheelListener l,
MouseWheelListener oldl) {
return (MouseWheelListener) removeInternal(l, oldl);
}
/**
* Returns the resulting multicast listener from adding listener-a
* and listener-b together.
* If listener-a is null, it returns listener-b;
* If listener-b is null, it returns listener-a
* If neither are null, then it creates and returns
* a new AWTEventMulticaster instance which chains a with b.
* @param a event listener-a
* @param b event listener-b
*/
protected static EventListener addInternal(EventListener a, EventListener b) {
if (a == null) return b;
if (b == null) return a;
return new AWTEventMulticaster(a, b);
}
/**
* Returns the resulting multicast listener after removing the
* old listener from listener-l.
* If listener-l equals the old listener OR listener-l is null,
* returns null.
* Else if listener-l is an instance of AWTEventMulticaster,
* then it removes the old listener from it.
* Else, returns listener l.
* @param l the listener being removed from
* @param oldl the listener being removed
*/
protected static EventListener removeInternal(EventListener l, EventListener oldl) {
if (l == oldl || l == null) {
return null;
} else if (l instanceof AWTEventMulticaster) {
return ((AWTEventMulticaster)l).remove(oldl);
} else {
return l; // it's not here
}
}
/* Serialization support.
*/
protected void saveInternal(ObjectOutputStream s, String k) throws IOException {
if (a instanceof AWTEventMulticaster) {
((AWTEventMulticaster)a).saveInternal(s, k);
}
else if (a instanceof Serializable) {
s.writeObject(k);
s.writeObject(a);
}
if (b instanceof AWTEventMulticaster) {
((AWTEventMulticaster)b).saveInternal(s, k);
}
else if (b instanceof Serializable) {
s.writeObject(k);
s.writeObject(b);
}
}
protected static void save(ObjectOutputStream s, String k, EventListener l) throws IOException {
if (l == null) {
return;
}
else if (l instanceof AWTEventMulticaster) {
((AWTEventMulticaster)l).saveInternal(s, k);
}
else if (l instanceof Serializable) {
s.writeObject(k);
s.writeObject(l);
}
}
/*
* Recursive method which returns a count of the number of listeners in
* EventListener, handling the (common) case of l actually being an
* AWTEventMulticaster. Additionally, only listeners of type listenerType
* are counted. Method modified to fix bug 4513402. -bchristi
*/
private static int getListenerCount(EventListener l, Class<?> listenerType) {
if (l instanceof AWTEventMulticaster) {
AWTEventMulticaster mc = (AWTEventMulticaster)l;
return getListenerCount(mc.a, listenerType) +
getListenerCount(mc.b, listenerType);
}
else {
// Only count listeners of correct type
return listenerType.isInstance(l) ? 1 : 0;
}
}
/*
* Recusive method which populates EventListener array a with EventListeners
* from l. l is usually an AWTEventMulticaster. Bug 4513402 revealed that
* if l differed in type from the element type of a, an ArrayStoreException
* would occur. Now l is only inserted into a if it's of the appropriate
* type. -bchristi
*/
private static int populateListenerArray(EventListener[] a, EventListener l, int index) {
if (l instanceof AWTEventMulticaster) {
AWTEventMulticaster mc = (AWTEventMulticaster)l;
int lhs = populateListenerArray(a, mc.a, index);
return populateListenerArray(a, mc.b, lhs);
}
else if (a.getClass().getComponentType().isInstance(l)) {
a[index] = l;
return index + 1;
}
// Skip nulls, instances of wrong class
else {
return index;
}
}
/**
* Returns an array of all the objects chained as
* <code>FooListeners by the specified
* <code>java.util.EventListener.
* <code>FooListeners are chained by the
* <code>AWTEventMulticaster using the
* <code>addFooListener method.
* If a <code>null listener is specified, this method returns an
* empty array. If the specified listener is not an instance of
* <code>AWTEventMulticaster, this method returns an array which
* contains only the specified listener. If no such listeners are chained,
* this method returns an empty array.
*
* @param l the specified <code>java.util.EventListener
* @param listenerType the type of listeners requested; this parameter
* should specify an interface that descends from
* <code>java.util.EventListener
* @return an array of all objects chained as
* <code>FooListeners by the specified multicast
* listener, or an empty array if no such listeners have been
* chained by the specified multicast listener
* @exception NullPointerException if the specified
* {@code listenertype} parameter is {@code null}
* @exception ClassCastException if <code>listenerType
* doesn't specify a class or interface that implements
* <code>java.util.EventListener
*
* @since 1.4
*/
@SuppressWarnings("unchecked")
public static <T extends EventListener> T[]
getListeners(EventListener l, Class<T> listenerType)
{
if (listenerType == null) {
throw new NullPointerException ("Listener type should not be null");
}
int n = getListenerCount(l, listenerType);
T[] result = (T[])Array.newInstance(listenerType, n);
populateListenerArray(result, l, 0);
return result;
}
}
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