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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

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package java.awt.dnd;

/**

* An abstract adapter class for receiving drop target events. The methods in

* this class are empty. This class exists only as a convenience for creating

* listener objects.

* <p>

* Extend this class to create a <code>DropTargetEvent</code> listener

* and override the methods for the events of interest. (If you implement the

* <code>DropTargetListener</code> interface, you have to define all of

* the methods in it. This abstract class defines a null implementation for

* every method except <code>drop(DropTargetDropEvent)</code>, so you only have

* to define methods for events you care about.) You must provide an

* implementation for at least <code>drop(DropTargetDropEvent)</code>. This

* method cannot have a null implementation because its specification requires

* that you either accept or reject the drop, and, if accepted, indicate

* whether the drop was successful.

* <p>

* Create a listener object using the extended class and then register it with

* a <code>DropTarget</code>. When the drag enters, moves over, or exits

* the operable part of the drop site for that <code>DropTarget</code>, when

* the drop action changes, and when the drop occurs, the relevant method in

* the listener object is invoked, and the <code>DropTargetEvent</code> is

* passed to it.

* <p>

* The operable part of the drop site for the <code>DropTarget</code> is

* the part of the associated <code>Component</code>'s geometry that is not

* obscured by an overlapping top-level window or by another

* <code>Component</code> higher in the Z-order that has an associated active

* <code>DropTarget</code>.

* <p>

* During the drag, the data associated with the current drag operation can be

* retrieved by calling <code>getTransferable()</code> on

* <code>DropTargetDragEvent</code> instances passed to the listener's

* methods.

* <p>

* Note that <code>getTransferable()</code> on the

* <code>DropTargetDragEvent</code> instance should only be called within the

* respective listener's method and all the necessary data should be retrieved

* from the returned <code>Transferable</code> before that method returns.

*

* @see DropTargetEvent

* @see DropTargetListener

*

* @author David Mendenhall

* @since 1.4

*/

public abstract class DropTargetAdapter implements DropTargetListener {

/**

* Called while a drag operation is ongoing, when the mouse pointer enters

* the operable part of the drop site for the <code>DropTarget</code>

* registered with this listener.

*

* @param dtde the <code>DropTargetDragEvent</code>

*/

public void dragEnter(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 <code>DropTarget</code>

* registered with this listener.

*

* @param dtde the <code>DropTargetDragEvent</code>

*/

public void dragOver(DropTargetDragEvent dtde) {}

/**

* Called if the user has modified

* the current drop gesture.

*

* @param dtde the <code>DropTargetDragEvent</code>

*/

public void dropActionChanged(DropTargetDragEvent dtde) {}

/**

* Called while a drag operation is ongoing, when the mouse pointer has

* exited the operable part of the drop site for the

* <code>DropTarget</code> registered with this listener.

*

* @param dte the <code>DropTargetEvent</code>

*/

public void dragExit(DropTargetEvent dte) {}

}