Java java.awt Class EventQueue（JDK8）

Constructor Detail

• EventQueue

  public EventQueue()

Method Detail

• postEvent

  public void postEvent(AWTEvent theEvent)

  Posts a 1.1-style event to the EventQueue. If there is an existing event on the queue with the same ID and event source, the source Component's coalesceEvents method will be called.

  Parameters:

  theEvent - an instance of java.awt.AWTEvent, or a subclass of it

  Throws:

  NullPointerException - if theEvent is null

• getNextEvent

  public AWTEvent getNextEvent()
                        throws InterruptedException

  Removes an event from the EventQueue and returns it. This method will block until an event has been posted by another thread.

  Returns:

  the next AWTEvent

  Throws:

  InterruptedException - if any thread has interrupted this thread

• peekEvent

  public AWTEvent peekEvent()

  Returns the first event on the EventQueue without removing it.

  Returns:

  the first event

• peekEvent

  public AWTEvent peekEvent(int id)

  Returns the first event with the specified id, if any.

  Parameters:

  id - the id of the type of event desired

  Returns:

  the first event of the specified id or null if there is no such event

• dispatchEvent

  protected void dispatchEvent(AWTEvent event)

  Dispatches an event. The manner in which the event is dispatched depends upon the type of the event and the type of the event's source object:

  Event Type	Source Type	Dispatched To
  ActiveEvent	Any	event.dispatch()
  Other	Component	source.dispatchEvent(AWTEvent)
  Other	MenuComponent	source.dispatchEvent(AWTEvent)
  Other	Other	No action (ignored)

  Parameters:

  event - an instance of java.awt.AWTEvent, or a subclass of it

  Throws:

  NullPointerException - if event is null

  Since:

  1.2

• getMostRecentEventTime

  public static long getMostRecentEventTime()

  Returns the timestamp of the most recent event that had a timestamp, and that was dispatched from the EventQueue associated with the calling thread. If an event with a timestamp is currently being dispatched, its timestamp will be returned. If no events have yet been dispatched, the EventQueue's initialization time will be returned instead.In the current version of the JDK, only InputEvents, ActionEvents, and InvocationEvents have timestamps; however, future versions of the JDK may add timestamps to additional event types. Note that this method should only be invoked from an application's event dispatching thread. If this method is invoked from another thread, the current system time (as reported by System.currentTimeMillis()) will be returned instead.

  Returns:

  the timestamp of the last InputEvent, ActionEvent, or InvocationEvent to be dispatched, or System.currentTimeMillis() if this method is invoked on a thread other than an event dispatching thread

  Since:

  1.4

  See Also:

  InputEvent.getWhen(), ActionEvent.getWhen(), InvocationEvent.getWhen(), isDispatchThread()

• getCurrentEvent

  public static AWTEvent getCurrentEvent()

  Returns the the event currently being dispatched by the EventQueue associated with the calling thread. This is useful if a method needs access to the event, but was not designed to receive a reference to it as an argument. Note that this method should only be invoked from an application's event dispatching thread. If this method is invoked from another thread, null will be returned.

  Returns:

  the event currently being dispatched, or null if this method is invoked on a thread other than an event dispatching thread

  Since:

  1.4

• push

  public void push(EventQueue newEventQueue)

  Replaces the existing EventQueue with the specified one. Any pending events are transferred to the new EventQueue for processing by it.

  Parameters:

  newEventQueue - an EventQueue (or subclass thereof) instance to be use

  Throws:

  NullPointerException - if newEventQueue is null

  Since:

  1.2

  See Also:

  pop()

• pop

  protected void pop()
              throws EmptyStackException

  Stops dispatching events using this EventQueue. Any pending events are transferred to the previous EventQueue for processing.

  Warning: To avoid deadlock, do not declare this method synchronized in a subclass.

  Throws:

  EmptyStackException - if no previous push was made on this EventQueue

  Since:

  1.2

  See Also:

  push(java.awt.EventQueue)

• createSecondaryLoop

  public SecondaryLoop createSecondaryLoop()

  Creates a new secondary loop associated with this event queue. Use the SecondaryLoop.enter() and SecondaryLoop.exit() methods to start and stop the event loop and dispatch the events from this queue.

  Returns:

  secondaryLoop A new secondary loop object, which can be used to launch a new nested event loop and dispatch events from this queue

  Since:

  1.7

  See Also:

  SecondaryLoop.enter(), SecondaryLoop.exit()

• isDispatchThread

  public static boolean isDispatchThread()

  Returns true if the calling thread is the current AWT EventQueue's dispatch thread. Use this method to ensure that a particular task is being executed (or not being) there.

  Note: use the invokeLater(java.lang.Runnable) or invokeAndWait(java.lang.Runnable) methods to execute a task in the current AWT EventQueue's dispatch thread.

  Returns:

  true if running in the current AWT EventQueue's dispatch thread

  Since:

  1.2

  See Also:

  invokeLater(java.lang.Runnable), invokeAndWait(java.lang.Runnable), Toolkit.getSystemEventQueue()

• invokeLater

  public static void invokeLater(Runnable runnable)

  Causes runnable to have its run method called in the dispatch thread of the system EventQueue. This will happen after all pending events are processed.

  Parameters:

  runnable - the Runnable whose run method should be executed asynchronously in the event dispatch thread of the system EventQueue

  Since:

  1.2

  See Also:

  invokeAndWait(java.lang.Runnable), Toolkit.getSystemEventQueue(), isDispatchThread()

• invokeAndWait

  public static void invokeAndWait(Runnable runnable)
                            throws InterruptedException,
                                   InvocationTargetException

  Causes runnable to have its run method called in the dispatch thread of the system EventQueue. This will happen after all pending events are processed. The call blocks until this has happened. This method will throw an Error if called from the event dispatcher thread.

  Parameters:

  runnable - the Runnable whose run method should be executed synchronously in the event dispatch thread of the system EventQueue

  Throws:

  InterruptedException - if any thread has interrupted this thread

  InvocationTargetException - if an throwable is thrown when running runnable

  Since:

  1.2

  See Also:

  invokeLater(java.lang.Runnable), Toolkit.getSystemEventQueue(), isDispatchThread()