Name: tb29552 Date: 11/10/98


/*

The simple test program appended at the end of
this message generates a
NullPointerException when dragging is started, if
run under Motif (Solaris 2.6 sparc). It runs with
no error if run under Windows NT.

In both cases, we are using 1.2-rc1.

Here is the trace:

java.lang.NullPointerException
        at sun.awt.motif.MDragSourceContextPeer.startDrag(Compiled Code)
        at java.awt.dnd.DragSource.startDrag(Compiled Code)
        at java.awt.dnd.DragSource.startDrag(Compiled Code)
        at java.awt.dnd.DragGestureEvent.startDrag(Compiled Code)
        at DnDtest.dragGestureRecognized(Compiled Code)
        at java.awt.dnd.DragGestureRecognizer.fireDragGestureRecognized(Compiled Code)
        at sun.awt.motif.MMouseDragGestureRecognizer.mouseDragged(Compiled Code)
        at java.awt.Component.processMouseMotionEvent(Compiled Code)
        at java.awt.Component.processEvent(Compiled Code)
        at java.awt.Container.processEvent(Compiled Code)
        at java.awt.Window.processEvent(Compiled Code)
        at java.awt.Component.dispatchEventImpl(Compiled Code)
        at java.awt.Container.dispatchEventImpl(Compiled Code)
        at java.awt.Window.dispatchEventImpl(Compiled Code)
        at java.awt.Component.dispatchEvent(Compiled Code)
        at java.awt.EventQueue.dispatchEvent(Compiled Code)
        at java.awt.EventDispatchThread.run(Compiled Code)
java.awt.dnd.InvalidDnDOperationException: The operation requested cannot be performed by the DnD system since it is not in the appropriate state
        at sun.awt.motif.MDragSourceContextPeer.startDrag(Compiled Code)
        at java.awt.dnd.DragSource.startDrag(Compiled Code)
        at java.awt.dnd.DragSource.startDrag(Compiled Code)
        at java.awt.dnd.DragGestureEvent.startDrag(Compiled Code)
        at DnDtest.dragGestureRecognized(Compiled Code)
        at java.awt.dnd.DragGestureRecognizer.fireDragGestureRecognized(Compiled Code)
        at sun.awt.motif.MMouseDragGestureRecognizer.mouseDragged(Compiled Code)
        at java.awt.Component.processMouseMotionEvent(Compiled Code)
        at java.awt.Component.processEvent(Compiled Code)
        at java.awt.Container.processEvent(Compiled Code)
        at java.awt.Window.processEvent(Compiled Code)
        at java.awt.Component.dispatchEventImpl(Compiled Code)
        at java.awt.Container.dispatchEventImpl(Compiled Code)
        at java.awt.Window.dispatchEventImpl(Compiled Code)
        at java.awt.Component.dispatchEvent(Compiled Code)
        at java.awt.EventQueue.dispatchEvent(Compiled Code)
        at java.awt.EventDispatchThread.run(Compiled Code)

------------------------------------------
*/
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.dnd.peer.*;

public class DnDtest extends JFrame implements DragGestureListener, DragSourceListener {

    public DnDtest () {

        JComponent content = (JComponent) getContentPane();
        content.setLayout(new FlowLayout());
        content.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
        content.setBackground(Color.white);

        JButton close = new JButton("Close");
        close.setMaximumSize(close.getPreferredSize());
        close.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                setVisible(false);
                dispose();
            }
        });
        content.add(close);

        DragSource source = DragSource.getDefaultDragSource();

        DragGestureRecognizer dgc = source.createDefaultDragGestureRecognizer(
                                      this, DnDConstants.ACTION_COPY, this);
    }

    //
    // DragGestureListener interface
    //

    public void dragGestureRecognized(DragGestureEvent evt) {

        StringSelection data = new StringSelection("some data");

        try {
            evt.startDrag(DragSource.DefaultCopyNoDrop, data, this);
        } catch(Exception e) {
            e.printStackTrace();
            System.exit(0);
        }
    }

    //
    // DragSourceListener interface
    //

    public void dragEnter(DragSourceDragEvent drag) {
        System.err.println("enter");
    }

    public void dragOver(DragSourceDragEvent drag) {
        System.err.println("over");
    }

    public void dropActionChanged(DragSourceDragEvent drag) {
        System.err.println("action changed");
    }

    public void dragExit(DragSourceEvent evt) {
        System.err.println("exit");
    }

    public void dragDropEnd(DragSourceDropEvent drop) {
        System.err.println("drop end");
    }



    static public void main(String[] args) {
        final JFrame myself = new DnDtest ();

        myself.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        myself.addWindowListener(new WindowAdapter() {
            public void windowClosed(WindowEvent evt) {
                System.exit(0);
            }
        });

        myself.pack();
        myself.show();
    }
}

(Review ID: 42449)
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