| ListSelectionEvent |
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typedict |
| |
A
ListSelectionEvent
is a new Swing event that indicates the current selection in a
JList
has changed.
JList
does not support
ItemEvent,
which means an
itemStateChanged
event handler that worked with an AWT
List
will not work with a
JList.
The fields in a
ListSelectionEvent
are:
| firstindex |
An
int
that is the index, if it is non-negative, of the first element in the list
that may have had its selection state changed.
Event handlers rarely use this field because getting the selected items
directly from the
JList
is easy.
| | 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.
| | lastindex |
An
int
that is the index, if it is non-negative, of the last element in the list
that may have had its selection state changed.
Event handlers rarely use this field because getting the selected items
directly from the
JList
is easy.
| | sequence |
An
int
that is non-zero if the event belongs to a series of related events and
more will follow.
Event handlers often ignore
ListSelectionEvents
that have a non-zero
sequence
and simply wait for the last event in the sequence before doing any real work.
|
JList
is the only component that can receive
ListSelectionEvents,
but they only arrive if the component has defined a
valueChanged
event handler.
| |
| Event Handlers: |
valueChanged
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| Example: |
The program,
import yoix.*.*;
JFrame f = {
FlowLayout layoutmanager = {
double vgap = 72;
};
Array layout = {
new JList {
Color background = Color.white;
int scroll = VERTICAL;
int rows = 4;
int multiplemode = TRUE;
Array items = {
"Now is the time", NULL,
"for", NULL,
"all good men", "two",
"to come to the aid", NULL,
"of their", NULL,
"party", NULL,
};
valueChanged(Event e) {
if (e.sequence == 0)
printf("valueChanged: selected=%O\n", selected);
else printf("valueChanged: e=%O\n", e);
}
}
};
};
f.visible = TRUE;
puts a
JList
in a
JFrame
and defines a handler for
ListSelectionEvents.
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| See Also: |
ActionEvent,
AdjustmentEvent,
CaretEvent,
ChangeEvent,
ComponentEvent,
DragGestureEvent,
DragSourceEvent,
DropTargetEvent,
Event,
FocusEvent,
HyperlinkEvent,
InvocationEvent,
invokeLater,
isDispatchThread,
ItemEvent,
KeyEvent,
MouseEvent,
MouseWheelEvent,
PaintEvent,
postEvent,
TextEvent,
TreeSelectionEvent,
WindowEvent
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Yoix is a registered trademark of AT&T Inc.
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