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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) {}
}