InvocationEvent (Java Platform SE 7 )
Keywords: java.awt.event.InvocationEvent class

java.awt.event

## Class InvocationEvent

- java.lang.Object
- - java.util.EventObject
  - - java.awt.AWTEvent
    - - java.awt.event.InvocationEvent

- All Implemented Interfaces:
    ActiveEvent, Serializable

      public class InvocationEvent
      extends AWTEvent
      implements ActiveEvent

  An event which executes the `run()` method on a `Runnable` when dispatched by the AWT event dispatcher thread. This class can be used as a reference implementation of `ActiveEvent` rather than declaring a new class and defining `dispatch()`.

  Instances of this class are placed on the `EventQueue` by calls to `invokeLater` and `invokeAndWait`. Client code can use this fact to write replacement functions for `invokeLater` and `invokeAndWait` without writing special-case code in any `AWTEventListener` objects.

  An unspecified behavior will be caused if the `id` parameter of any particular `InvocationEvent` instance is not in the range from `INVOCATION_FIRST` to `INVOCATION_LAST`.

  Since:
    1.2
  See Also:
    `ActiveEvent`, `EventQueue.invokeLater(java.lang.Runnable)`, `EventQueue.invokeAndWait(java.lang.Runnable)`, `AWTEventListener`, Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected boolean` | `catchExceptions` Set to true if dispatch() catches Throwable and stores it in the exception instance variable.
    `static int` | `INVOCATION_DEFAULT` The default id for all InvocationEvents.
    `static int` | `INVOCATION_FIRST` Marks the first integer id for the range of invocation event ids.
    `static int` | `INVOCATION_LAST` Marks the last integer id for the range of invocation event ids.
    `protected Object` | `notifier` The (potentially null) Object whose notifyAll() method will be called immediately after the Runnable.run() method has returned or thrown an exception.
    `protected Runnable` | `runnable` The Runnable whose run() method will be called.

    - ### Fields inherited from class java.awt.AWTEvent

      `ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, HIERARCHY_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, INVOCATION_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, PAINT_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, WINDOW_STATE_EVENT_MASK`

    - ### Fields inherited from class java.util.EventObject

      `source`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `InvocationEvent(Object source, int id, Runnable runnable, Object notifier, boolean catchThrowables)` Constructs an `InvocationEvent` with the specified source and ID which will execute the runnable's `run` method when dispatched.
    `` | `InvocationEvent(Object source, Runnable runnable)` Constructs an `InvocationEvent` with the specified source which will execute the runnable's `run` method when dispatched.
    `` | `InvocationEvent(Object source, Runnable runnable, Object notifier, boolean catchThrowables)` Constructs an `InvocationEvent` with the specified source which will execute the runnable's `run` method when dispatched.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `dispatch()` Executes the Runnable's `run()` method and notifies the notifier (if any) when `run()` has returned or thrown an exception.
    `Exception` | `getException()` Returns any Exception caught while executing the Runnable's `run()` method.
    `Throwable` | `getThrowable()` Returns any Throwable caught while executing the Runnable's `run()` method.
    `long` | `getWhen()` Returns the timestamp of when this event occurred.
    `boolean` | `isDispatched()` Returns `true` if the event is dispatched or any exception is thrown while dispatching, `false` otherwise.
    `String` | `paramString()` Returns a parameter string identifying this event.

    - ### Methods inherited from class java.awt.AWTEvent

      `consume, getID, isConsumed, setSource, toString`

    - ### Methods inherited from class java.util.EventObject

      `getSource`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### INVOCATION_FIRST

          public static final int INVOCATION_FIRST

      Marks the first integer id for the range of invocation event ids.
      See Also:
        Constant Field Values

    - #### INVOCATION_DEFAULT

          public static final int INVOCATION_DEFAULT

      The default id for all InvocationEvents.
      See Also:
        Constant Field Values

    - #### INVOCATION_LAST

          public static final int INVOCATION_LAST

      Marks the last integer id for the range of invocation event ids.
      See Also:
        Constant Field Values

    - #### runnable

          protected Runnable runnable

      The Runnable whose run() method will be called.

    - #### notifier

          protected Object notifier

      The (potentially null) Object whose notifyAll() method will be called immediately after the Runnable.run() method has returned or thrown an exception.
      See Also:
        `isDispatched()`

    - #### catchExceptions

          protected boolean catchExceptions

      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.

  - ### Constructor Detail

    - #### InvocationEvent

          public InvocationEvent(Object source,
                         Runnable runnable)

      Constructs an `InvocationEvent` with the specified source which will execute the runnable's `run` method when dispatched.

      This is a convenience constructor. An invocation of the form `InvocationEvent(source, runnable)` behaves in exactly the same way as the invocation of ``InvocationEvent`(source, runnable, null, false)`.

      This method throws an `IllegalArgumentException` if `source` is `null`.

      Parameters:
        `source` - The `Object` that originated the event
        `runnable` - The `Runnable` whose `run` method will be executed
      Throws:
        `IllegalArgumentException` - if `source` is null
      See Also:
        `EventObject.getSource()`, `InvocationEvent(Object, Runnable, Object, boolean)`

    - #### InvocationEvent

          public InvocationEvent(Object source,
                         Runnable runnable,
                         Object notifier,
                         boolean catchThrowables)

      Constructs an `InvocationEvent` with the specified source which will execute the runnable's `run` method when dispatched. If notifier is non-`null`, `notifyAll()` will be called on it immediately after `run` has returned or thrown an exception.

      An invocation of the form `InvocationEvent(source, runnable, notifier, catchThrowables)` behaves in exactly the same way as the invocation of ``InvocationEvent`(source, InvocationEvent.INVOCATION_DEFAULT, runnable, notifier, catchThrowables)`.

      This method throws an `IllegalArgumentException` if `source` is `null`.

      Parameters:
        `source` - The `Object` that originated the event
        `runnable` - The `Runnable` whose `run` method will be executed
        `notifier` - The `Object` whose `notifyAll` method will be called after `Runnable.run` has returned or thrown an exception
        `catchThrowables` - Specifies whether `dispatch` should catch Throwable when executing the `Runnable`'s `run` method, or should instead propagate those Throwables to the EventDispatchThread's dispatch loop
      Throws:
        `IllegalArgumentException` - if `source` is null
      See Also:
        `EventObject.getSource()`, `InvocationEvent(Object, int, Runnable, Object, boolean)`

    - #### InvocationEvent

          protected InvocationEvent(Object source,
                         int id,
                         Runnable runnable,
                         Object notifier,
                         boolean catchThrowables)

      Constructs an `InvocationEvent` with the specified source and ID which will execute the runnable's `run` method when dispatched. If notifier is non-`null`, `notifyAll` will be called on it immediately after `run` has returned or thrown an exception.

      This method throws an `IllegalArgumentException` if `source` is `null`.

      Parameters:
        `source` - The `Object` that originated the event
        `id` - An integer indicating the type of event. For information on allowable values, see the class description for `InvocationEvent`
        `runnable` - The `Runnable` whose `run` method will be executed
        `notifier` - The `Object` whose `notifyAll` method will be called after `Runnable.run` has returned or thrown an exception
        `catchThrowables` - Specifies whether `dispatch` should catch Throwable when executing the `Runnable`'s `run` method, or should instead propagate those Throwables to the EventDispatchThread's dispatch loop
      Throws:
        `IllegalArgumentException` - if `source` is null
      See Also:
        `EventObject.getSource()`, `AWTEvent.getID()`

  - ### Method Detail

    - #### dispatch

          public void dispatch()

      Executes the Runnable's `run()` method and notifies the notifier (if any) when `run()` has returned or thrown an exception.
      Specified by:
        `dispatch` in interface `ActiveEvent`
      See Also:
        `isDispatched()`

    - #### getException

          public Exception getException()

      Returns any Exception caught while executing the Runnable's `run()` method.
      Returns:
        A reference to the Exception if one was thrown; null if no Exception was thrown or if this InvocationEvent does not catch exceptions

    - #### getThrowable

          public Throwable getThrowable()

      Returns any Throwable caught while executing the Runnable's `run()` method.
      Returns:
        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

    - #### getWhen

          public long getWhen()

      Returns the timestamp of when this event occurred.
      Returns:
        this event's timestamp
      Since:
        1.4

    - #### isDispatched

          public boolean isDispatched()

      Returns `true` if the event is dispatched or any exception is thrown while dispatching, `false` otherwise. The method should be called by a waiting thread that calls the `notifier.wait()` method. Since spurious wakeups are possible (as explained in `Object.wait()`), this method should be used in a waiting loop to ensure that the event got dispatched:

               while (!event.isDispatched()) {
                   notifier.wait();
               }

      If the waiting thread wakes up without dispatching the event, the `isDispatched()` method returns `false`, and the `while` loop executes once more, thus, causing the awakened thread to revert to the waiting mode.

      If the `notifier.notifyAll()` happens before the waiting thread enters the `notifier.wait()` method, the `while` loop ensures that the waiting thread will not enter the `notifier.wait()` method. Otherwise, there is no guarantee that the waiting thread will ever be woken from the wait.

      Returns:
        `true` if the event has been dispatched, or any exception has been thrown while dispatching, `false` otherwise
      Since:
        1.7
      See Also:
        `dispatch()`, `notifier`, `catchExceptions`

    - #### paramString

          public String paramString()

      Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.
      Overrides:
        `paramString` in class `AWTEvent`
      Returns:
        A string identifying the event and its attributes

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