The InvocationEvent.java Java example source code
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* published by the Free Software Foundation. Oracle designates this
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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package java.awt.event;
import sun.awt.AWTAccessor;
import java.awt.ActiveEvent;
import java.awt.AWTEvent;
/**
* An event which executes the <code>run() method on a Runnable
* </code> when dispatched by the AWT event dispatcher thread. This class can
* be used as a reference implementation of <code>ActiveEvent rather
* than declaring a new class and defining <code>dispatch().
*
* Instances of this class are placed on the <code>EventQueue by calls
* to <code>invokeLater and invokeAndWait. Client code
* can use this fact to write replacement functions for <code>invokeLater
* </code> and invokeAndWait without writing special-case code
* in any <code>AWTEventListener objects.
* <p>
* An unspecified behavior will be caused if the {@code id} parameter
* of any particular {@code InvocationEvent} instance is not
* in the range from {@code INVOCATION_FIRST} to {@code INVOCATION_LAST}.
*
* @author Fred Ecks
* @author David Mendenhall
*
* @see java.awt.ActiveEvent
* @see java.awt.EventQueue#invokeLater
* @see java.awt.EventQueue#invokeAndWait
* @see AWTEventListener
*
* @since 1.2
*/
public class InvocationEvent extends AWTEvent implements ActiveEvent {
static {
AWTAccessor.setInvocationEventAccessor(new AWTAccessor.InvocationEventAccessor() {
@Override
public void dispose(InvocationEvent invocationEvent) {
invocationEvent.finishedDispatching(false);
}
});
}
/**
* Marks the first integer id for the range of invocation event ids.
*/
public static final int INVOCATION_FIRST = 1200;
/**
* The default id for all InvocationEvents.
*/
public static final int INVOCATION_DEFAULT = INVOCATION_FIRST;
/**
* Marks the last integer id for the range of invocation event ids.
*/
public static final int INVOCATION_LAST = INVOCATION_DEFAULT;
/**
* The Runnable whose run() method will be called.
*/
protected Runnable runnable;
/**
* The (potentially null) Object whose notifyAll() method will be called
* immediately after the Runnable.run() method has returned or thrown an exception
* or after the event was disposed.
*
* @see #isDispatched
*/
protected volatile Object notifier;
/**
* The (potentially null) Runnable whose run() method will be called
* immediately after the event was dispatched or disposed.
*
* @see #isDispatched
* @since 1.8
*/
private final Runnable listener;
/**
* Indicates whether the <code>run() method of the runnable
* was executed or not.
*
* @see #isDispatched
* @since 1.7
*/
private volatile boolean dispatched = false;
/**
* Set to true if dispatch() catches Throwable and stores it in the
* exception instance variable. If false, Throwables are propagated up
* to the EventDispatchThread's dispatch loop.
*/
protected boolean catchExceptions;
/**
* The (potentially null) Exception thrown during execution of the
* Runnable.run() method. This variable will also be null if a particular
* instance does not catch exceptions.
*/
private Exception exception = null;
/**
* The (potentially null) Throwable thrown during execution of the
* Runnable.run() method. This variable will also be null if a particular
* instance does not catch exceptions.
*/
private Throwable throwable = null;
/**
* The timestamp of when this event occurred.
*
* @serial
* @see #getWhen
*/
private long when;
/*
* JDK 1.1 serialVersionUID.
*/
private static final long serialVersionUID = 436056344909459450L;
/**
* Constructs an <code>InvocationEvent with the specified
* source which will execute the runnable's <code>run
* method when dispatched.
* <p>This is a convenience constructor. An invocation of the form
* <tt>InvocationEvent(source, runnable)
* behaves in exactly the same way as the invocation of
* <tt>{@link #InvocationEvent(Object, Runnable, Object, boolean) InvocationEvent}(source, runnable, null, false).
* <p> This method throws an IllegalArgumentException
* if <code>source is null.
*
* @param source The <code>Object that originated the event
* @param runnable The <code>Runnable whose run
* method will be executed
* @throws IllegalArgumentException if <code>source is null
*
* @see #getSource()
* @see #InvocationEvent(Object, Runnable, Object, boolean)
*/
public InvocationEvent(Object source, Runnable runnable) {
this(source, INVOCATION_DEFAULT, runnable, null, null, false);
}
/**
* Constructs an <code>InvocationEvent with the specified
* source which will execute the runnable's <code>run
* method when dispatched. If notifier is non-<code>null,
* <code>notifyAll() will be called on it
* immediately after <code>run has returned or thrown an exception.
* <p>An invocation of the form InvocationEvent(source,
* runnable, notifier, catchThrowables)</tt>
* behaves in exactly the same way as the invocation of
* <tt>{@link #InvocationEvent(Object, int, Runnable, Object, boolean) InvocationEvent}(source, InvocationEvent.INVOCATION_DEFAULT, runnable, notifier, catchThrowables).
* <p>This method throws an IllegalArgumentException
* if <code>source is null.
*
* @param source The <code>Object that originated
* the event
* @param runnable The <code>Runnable whose
* <code>run method will be
* executed
* @param notifier The {@code Object} whose <code>notifyAll
* method will be called after
* <code>Runnable.run has returned or
* thrown an exception or after the event was
* disposed
* @param catchThrowables Specifies whether <code>dispatch
* should catch Throwable when executing
* the <code>Runnable's run
* method, or should instead propagate those
* Throwables to the EventDispatchThread's
* dispatch loop
* @throws IllegalArgumentException if <code>source is null
*
* @see #getSource()
* @see #InvocationEvent(Object, int, Runnable, Object, boolean)
*/
public InvocationEvent(Object source, Runnable runnable, Object notifier,
boolean catchThrowables) {
this(source, INVOCATION_DEFAULT, runnable, notifier, null, catchThrowables);
}
/**
* Constructs an <code>InvocationEvent with the specified
* source which will execute the runnable's <code>run
* method when dispatched. If listener is non-<code>null,
* <code>listener.run() will be called immediately after
* <code>run has returned, thrown an exception or the event
* was disposed.
* <p>This method throws an IllegalArgumentException
* if <code>source is null.
*
* @param source The <code>Object that originated
* the event
* @param runnable The <code>Runnable whose
* <code>run method will be
* executed
* @param listener The <code>RunnableRunnable whose
* <code>run() method will be called
* after the {@code InvocationEvent}
* was dispatched or disposed
* @param catchThrowables Specifies whether <code>dispatch
* should catch Throwable when executing
* the <code>Runnable's run
* method, or should instead propagate those
* Throwables to the EventDispatchThread's
* dispatch loop
* @throws IllegalArgumentException if <code>source is null
*/
public InvocationEvent(Object source, Runnable runnable, Runnable listener,
boolean catchThrowables) {
this(source, INVOCATION_DEFAULT, runnable, null, listener, catchThrowables);
}
/**
* Constructs an <code>InvocationEvent with the specified
* source and ID which will execute the runnable's <code>run
* method when dispatched. If notifier is non-<code>null,
* <code>notifyAll will be called on it immediately after
* <code>run has returned or thrown an exception.
* <p>This method throws an
* <code>IllegalArgumentException if source
* is <code>null.
*
* @param source The <code>Object that originated
* the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link InvocationEvent}
* @param runnable The <code>Runnable whose
* <code>run method will be executed
* @param notifier The <code>Object whose notifyAll
* method will be called after
* <code>Runnable.run has returned or
* thrown an exception or after the event was
* disposed
* @param catchThrowables Specifies whether <code>dispatch
* should catch Throwable when executing the
* <code>Runnable's run
* method, or should instead propagate those
* Throwables to the EventDispatchThread's
* dispatch loop
* @throws IllegalArgumentException if <code>source is null
* @see #getSource()
* @see #getID()
*/
protected InvocationEvent(Object source, int id, Runnable runnable,
Object notifier, boolean catchThrowables) {
this(source, id, runnable, notifier, null, catchThrowables);
}
private InvocationEvent(Object source, int id, Runnable runnable,
Object notifier, Runnable listener, boolean catchThrowables) {
super(source, id);
this.runnable = runnable;
this.notifier = notifier;
this.listener = listener;
this.catchExceptions = catchThrowables;
this.when = System.currentTimeMillis();
}
/**
* Executes the Runnable's <code>run() method and notifies the
* notifier (if any) when <code>run() has returned or thrown an exception.
*
* @see #isDispatched
*/
public void dispatch() {
try {
if (catchExceptions) {
try {
runnable.run();
}
catch (Throwable t) {
if (t instanceof Exception) {
exception = (Exception) t;
}
throwable = t;
}
}
else {
runnable.run();
}
} finally {
finishedDispatching(true);
}
}
/**
* Returns any Exception caught while executing the Runnable's <code>run()
* </code> method.
*
* @return A reference to the Exception if one was thrown; null if no
* Exception was thrown or if this InvocationEvent does not
* catch exceptions
*/
public Exception getException() {
return (catchExceptions) ? exception : null;
}
/**
* Returns any Throwable caught while executing the Runnable's <code>run()
* </code> method.
*
* @return A reference to the Throwable if one was thrown; null if no
* Throwable was thrown or if this InvocationEvent does not
* catch Throwables
* @since 1.5
*/
public Throwable getThrowable() {
return (catchExceptions) ? throwable : null;
}
/**
* Returns the timestamp of when this event occurred.
*
* @return this event's timestamp
* @since 1.4
*/
public long getWhen() {
return when;
}
/**
* Returns {@code true} if the event is dispatched or any exception is
* thrown while dispatching, {@code false} otherwise. The method should
* be called by a waiting thread that calls the {@code notifier.wait()} method.
* Since spurious wakeups are possible (as explained in {@link Object#wait()}),
* this method should be used in a waiting loop to ensure that the event
* got dispatched:
* <pre>
* while (!event.isDispatched()) {
* notifier.wait();
* }
* </pre>
* If the waiting thread wakes up without dispatching the event,
* the {@code isDispatched()} method returns {@code false}, and
* the {@code while} loop executes once more, thus, causing
* the awakened thread to revert to the waiting mode.
* <p>
* If the {@code notifier.notifyAll()} happens before the waiting thread
* enters the {@code notifier.wait()} method, the {@code while} loop ensures
* that the waiting thread will not enter the {@code notifier.wait()} method.
* Otherwise, there is no guarantee that the waiting thread will ever be woken
* from the wait.
*
* @return {@code true} if the event has been dispatched, or any exception
* has been thrown while dispatching, {@code false} otherwise
* @see #dispatch
* @see #notifier
* @see #catchExceptions
* @since 1.7
*/
public boolean isDispatched() {
return dispatched;
}
/**
* Called when the event was dispatched or disposed
* @param dispatched true if the event was dispatched
* false if the event was disposed
*/
private void finishedDispatching(boolean dispatched) {
this.dispatched = dispatched;
if (notifier != null) {
synchronized (notifier) {
notifier.notifyAll();
}
}
if (listener != null) {
listener.run();
}
}
/**
* Returns a parameter string identifying this event.
* This method is useful for event-logging and for debugging.
*
* @return A string identifying the event and its attributes
*/
public String paramString() {
String typeStr;
switch(id) {
case INVOCATION_DEFAULT:
typeStr = "INVOCATION_DEFAULT";
break;
default:
typeStr = "unknown type";
}
return typeStr + ",runnable=" + runnable + ",notifier=" + notifier +
",catchExceptions=" + catchExceptions + ",when=" + when;
}
}
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