Java example source code file (DropTargetAdapter.java)

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Java - Java tags/keywords

droptargetadapter, droptargetlistener

The DropTargetAdapter.java Java example source code

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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 listener
 * and override the methods for the events of interest. (If you implement the
 * <code>DropTargetListener 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), so you only have
 * to define methods for events you care about.) You must provide an
 * implementation for at least <code>drop(DropTargetDropEvent). 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. When the drag enters, moves over, or exits
 * the operable part of the drop site for that <code>DropTarget, when
 * the drop action changes, and when the drop occurs, the relevant method in
 * the listener object is invoked, and the <code>DropTargetEvent is
 * passed to it.
 * <p>
 * The operable part of the drop site for the <code>DropTarget is
 * the part of the associated <code>Component's geometry that is not
 * obscured by an overlapping top-level window or by another
 * <code>Component higher in the Z-order that has an associated active
 * <code>DropTarget.
 * <p>
 * During the drag, the data associated with the current drag operation can be
 * retrieved by calling <code>getTransferable() on
 * <code>DropTargetDragEvent instances passed to the listener's
 * methods.
 * <p>
 * Note that <code>getTransferable() on the
 * <code>DropTargetDragEvent instance should only be called within the
 * respective listener's method and all the necessary data should be retrieved
 * from the returned <code>Transferable 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
     * registered with this listener.
     *
     * @param dtde the <code>DropTargetDragEvent
     */
    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
     * registered with this listener.
     *
     * @param dtde the <code>DropTargetDragEvent
     */
    public void dragOver(DropTargetDragEvent dtde) {}

    /**
     * Called if the user has modified
     * the current drop gesture.
     *
     * @param dtde the <code>DropTargetDragEvent
     */
    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 registered with this listener.
     *
     * @param dte the <code>DropTargetEvent
     */
    public void dragExit(DropTargetEvent dte) {}
}