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## java.awt.dnd
Interface DropTargetListener

All Superinterfaces:
  EventListener

All Known Implementing Classes:
  DropTarget, DropTargetAdapter

    public interface DropTargetListener

extends EventListener

The `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
`void` | `dragEnter(DropTargetDragEvent dtde)` Called while a drag operation is ongoing, when the mouse pointer enters the operable part of the drop site for the `DropTarget` 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 the `DropTarget` 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 the `DropTarget` 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 the `DropTarget` registered with this listener.
`void` | `dropActionChanged(DropTargetDragEvent dtde)` Called if the user has modified the current drop gesture.

Method Detail

### dragEnter

    void dragEnter(DropTargetDragEvent dtde)

  Called while a drag operation is ongoing, when the mouse pointer enters the operable part of the drop site for the `DropTarget` registered with this listener.

  Parameters:
    `dtde` - the `DropTargetDragEvent`

### dragOver

    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 the `DropTarget` registered with this listener.

  Parameters:
    `dtde` - the `DropTargetDragEvent`

### dropActionChanged

    void dropActionChanged(DropTargetDragEvent dtde)

  Called if the user has modified the current drop gesture.

  Parameters:
    `dtde` - the `DropTargetDragEvent`

### dragExit

    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 the `DropTarget` registered with this listener.

  Parameters:
    `dte` - the `DropTargetEvent`

### drop

    void drop(DropTargetDropEvent dtde)

  Called when the drag operation has terminated with a drop on the operable part of the drop site for the `DropTarget` 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 a `Transferable` object that represents the data object(s) to be transfered.

  From this method, the `DropTargetListener` shall accept or reject the drop via the acceptDrop(int dropAction) or rejectDrop() methods of the `DropTargetDropEvent` parameter.

  Subsequent to acceptDrop(), but not before, `DropTargetDropEvent`'s getTransferable() method may be invoked, and data transfer may be performed via the returned `Transferable`'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 the `DropTargetDropEvent`'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 the `Transferable` returned by `DropTargetDropEvent.getTransferable()` is guaranteed to succeed only if the data transfer is local; that is, only if `DropTargetDropEvent.isLocalTransfer()` returns `true`. Otherwise, the behavior of the call is implementation-dependent.

  Parameters:
    `dtde` - the `DropTargetDropEvent`

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.