Interface DropTargetListener
- All Superinterfaces:
EventListener
- All Known Implementing Classes:
DropTarget
,DropTargetAdapter
DropTargetListener
interface
is the callback interface used by the
DropTarget
class to provide
notification of DnD operations that involve
the subject DropTarget
. Methods of
this interface may be implemented to provide
"drag under" visual feedback to the user throughout
the Drag and Drop operation.
Create a listener object by implementing the interface and then register it
with a DropTarget
. When the drag enters, moves over, or exits
the operable part of the drop site for that DropTarget
, when
the drop action changes, and when the drop occurs, the relevant method in
the listener object is invoked, and the DropTargetEvent
is
passed to it.
The operable part of the drop site for the DropTarget
is
the part of the associated Component
's geometry that is not
obscured by an overlapping top-level window or by another
Component
higher in the Z-order that has an associated active
DropTarget
.
During the drag, the data associated with the current drag operation can be
retrieved by calling getTransferable()
on
DropTargetDragEvent
instances passed to the listener's
methods.
Note that getTransferable()
on the
DropTargetDragEvent
instance should only be called within the
respective listener's method and all the necessary data should be retrieved
from the returned Transferable
before that method returns.
- Since:
- 1.2
-
Method Summary
Modifier and TypeMethodDescriptionvoid
dragEnter
(DropTargetDragEvent dtde) Called while a drag operation is ongoing, when the mouse pointer enters the operable part of the drop site for theDropTarget
registered with this listener.void
dragExit
(DropTargetEvent dte) Called while a drag operation is ongoing, when the mouse pointer has exited the operable part of the drop site for theDropTarget
registered with this listener.void
dragOver
(DropTargetDragEvent dtde) Called when a drag operation is ongoing, while the mouse pointer is still over the operable part of the drop site for theDropTarget
registered with this listener.void
drop
(DropTargetDropEvent dtde) Called when the drag operation has terminated with a drop on the operable part of the drop site for theDropTarget
registered with this listener.void
Called if the user has modified the current drop gesture.
-
Method Details
-
dragEnter
Called while a drag operation is ongoing, when the mouse pointer enters the operable part of the drop site for theDropTarget
registered with this listener.- Parameters:
dtde
- theDropTargetDragEvent
-
dragOver
Called when a drag operation is ongoing, while the mouse pointer is still over the operable part of the drop site for theDropTarget
registered with this listener.- Parameters:
dtde
- theDropTargetDragEvent
-
dropActionChanged
Called if the user has modified the current drop gesture.- Parameters:
dtde
- theDropTargetDragEvent
-
dragExit
Called while a drag operation is ongoing, when the mouse pointer has exited the operable part of the drop site for theDropTarget
registered with this listener.- Parameters:
dte
- theDropTargetEvent
-
drop
Called when the drag operation has terminated with a drop on the operable part of the drop site for theDropTarget
registered with this listener.This method is responsible for undertaking the transfer of the data associated with the gesture. The
DropTargetDropEvent
provides a means to obtain aTransferable
object that represents the data object(s) to be transferred.From this method, the
DropTargetListener
shall accept or reject the drop via the acceptDrop(int dropAction) or rejectDrop() methods of theDropTargetDropEvent
parameter.Subsequent to acceptDrop(), but not before,
DropTargetDropEvent
's getTransferable() method may be invoked, and data transfer may be performed via the returnedTransferable
's getTransferData() method.At the completion of a drop, an implementation of this method is required to signal the success/failure of the drop by passing an appropriate
boolean
to theDropTargetDropEvent
's dropComplete(boolean success) method.Note: The data transfer should be completed before the call to the
DropTargetDropEvent
's dropComplete(boolean success) method. After that, a call to the getTransferData() method of theTransferable
returned byDropTargetDropEvent.getTransferable()
is guaranteed to succeed only if the data transfer is local; that is, only ifDropTargetDropEvent.isLocalTransfer()
returnstrue
. Otherwise, the behavior of the call is implementation-dependent.- Parameters:
dtde
- theDropTargetDropEvent
-