An
InvocationEvent
is a special, general-purpose event.
Yoix programs can build them and use
postEvent
to send them to the
invocationRun
event handler defined in any AWT or Swing component.
An
InvocationEvent
can grow, which means you can add fields whenever you want,
but your names must not collide with following fields:
| etc |
A field that is not currently used and may not be defined,
but it should be considered reserved for releases.
| | id |
An
Object
that must be an
int
or
String,
that identifies the type of this event.
A value that is a
String
must be the name of an event handler that can process this event.
A value that is an
int
must be a number that the
yoix.event.HandlerID
dictionary associates with an event handler that can process this event.
In practice,
id
is only used when you build an event that gets handed to
postEvent,
and in that case the value assigned to
id
is almost always a
String.
|
Most components can receive
InvocationEvents,
but they only arrive if the component has defined an
invocationRun
event handler.
InvocationEvents
are also used by the
JTable
event handlers
invocationAction,
invocationChange,
invocationEdit
and
invocationSelection
and the
JTree
event handler
invocationBrowse.
| |
| Event Handlers: |
invocationAction,
invocationChange,
invocationBrowse,
invocationEdit,
invocationRun,
invocationSelection
| | |
| Example: |
The program,
import yoix.*.*;
Button b = {
invocationRun(Event e) {
if (e.counter++ < 3)
printf("invocationRun: e=%O\n", e);
else exit(0);
}
};
InvocationEvent ie = {
String id = "invocationRun";
int counter = 0; // custom field
};
while (TRUE) {
postEvent(ie, b);
ie.counter++;
sleep(1.0);
}
prints
invocationRun: e=Event[2:0]
counter=1
>id=^"invocationRun"
invocationRun: e=Event[2:0]
counter=2
>id=^"invocationRun"
invocationRun: e=Event[2:0]
counter=3
>id=^"invocationRun"
on standard output.
Notice that we added a custom field named
counter
to the
InvocationEvent
that we sent to the button, and that the button's invocationRun
event handler checked and incremented counter each time it was called.
The important point to remember here is that
postEvent
always sends a copy of the event, rather than the event itself.
That means the button will not notice that
counter
changed right after
postEvent
returned and we will not notice that the button's
invocationRun
changed
counter
in the event that it received.
| | |
| See Also: |
ActionEvent,
AdjustmentEvent,
CaretEvent,
ChangeEvent,
ComponentEvent,
DragGestureEvent,
DragSourceEvent,
DropTargetEvent,
Event,
FocusEvent,
HyperlinkEvent,
invokeLater,
isDispatchThread,
ItemEvent,
KeyEvent,
ListSelectionEvent,
MouseEvent,
MouseWheelEvent,
PaintEvent,
postEvent,
TextEvent,
TreeSelectionEvent,
WindowEvent
|
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