InvocationEvent (Java Platform SE 8 )
Keywords: java.awt.event.InvocationEvent class
Date: 2020-03-26

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 or after the event was disposed.
    `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.
    `` | `InvocationEvent(Object source, Runnable runnable, Runnable listener, boolean catchThrowables)` Constructs an `InvocationEvent` with the specified source which will execute the runnable's `run` method when dispatched.

  - ### Method Summary

    All Methods Instance Methods Concrete 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 volatile Object notifier

      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 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 or after the event was disposed
        `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

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

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

      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
        `listener` - The `Runnable`Runnable whose `run()` method will be called after the `InvocationEvent` was dispatched or disposed
        `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

    - #### 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 or after the event was disposed
        `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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