Drag n Drop

[sun par]

I need to learn Drap n Drop capabilities of Swing. Can someone suggest some material for it??
Thanks

[Dirk Schreckmann]

I'd suggest taking a look at The Drag and Drop Trail of Sun's Java Tutorial, taking a look at The Drag and Drop section of the J2SE Documentation, and trying a quick search on this forum. (The search page link is at the top-right of this page.)
Good luck.
[ April 03, 2003: Message edited by: Dirk Schreckmann ]

[Manish Hatwalne]

Also have a look at this tip from the latest Tech Tip by Sun.
- Manish

[Yoo-Jin Lee]

Hi,
Here's some code for drag n drop and cut and paste:

 
package test.swing;
import uk.co.aps.swing.SwingWorker;
import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.event.*;
import javax.swing.*;
public class Progress
        extends JPanel {
    private BorderLayout borderLayout1 = new BorderLayout();
    private static JProgressBar bar = new JProgressBar();
    private JButton btn = new JButton();
    private final void pasteIt() {
        final SwingWorker worker = new SwingWorker() {
            public Object construct() {
                try {
                    int total = 100;
                    bar.setMaximum(total);
                    bar.setMinimum(0);
                    for (int i = 0; i < total; i++) {
                        try {
                            Thread.sleep(100);
                        }
                        catch (InterruptedException ex) {
                        }
                        bar.setValue(i);
                    }
                }
                catch (Exception e) {
                }
                return null;
            }
            public void finished() {
            }
        };
        worker.start();
    }
    public Progress() {
        try {
            jbInit();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
    private void jbInit() throws Exception {
        this.setLayout(borderLayout1);
        this.setDoubleBuffered(false);
        bar.setDoubleBuffered(false);
        btn.setDoubleBuffered(false);
        btn.setText("import");
        btn.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                pasteIt();
            }
        });
        this.add(bar, BorderLayout.SOUTH);
        this.add(btn, BorderLayout.CENTER);
    }
    public static void main(String[] args) {
        Progress dndTest = new Progress();
        javax.swing.JFrame frame = new javax.swing.JFrame();
        frame.getContentPane().add(dndTest,
                                   java.awt.BorderLayout.CENTER);
        frame.pack();
        frame.setSize(500, 100);
        frame.setLocation(300, 600);
        frame.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
//        uncomment to see it work correctly
//        dndTest.pasteIt();
    }
}
package test.swing;
import javax.swing.SwingUtilities;
/**
 * This is the 3rd version of SwingWorker (also known as
 * SwingWorker 3), an abstract class that you subclass to
 * perform GUI-related work in a dedicated thread.  For
 * instructions on using this class, see:
 *
 * <http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html>
 *
 * Note that the API changed slightly in the 3rd version:
 * You must now invoke start() on the SwingWorker after
 * creating it.
 */
public abstract class SwingWorker {
    private Object value;  // see getValue(), setValue()
    private Thread thread;
    /**
     * Class to maintain reference to current worker thread
     * under separate synchronization control.
     */
    private static class ThreadVar {
        private Thread thread;
        ThreadVar(Thread t) { thread = t; }
        synchronized Thread get() { return thread; }
        synchronized void clear() { thread = null; }
    }
    private ThreadVar threadVar;
    /**
     * Get the value produced by the worker thread, or null if it
     * hasn't been constructed yet.
     */
    protected synchronized Object getValue() {
        return value;
    }
    /**
     * Set the value produced by worker thread
     */
    private synchronized void setValue(Object x) {
        value = x;
    }
    /**
     * Compute the value to be returned by the <code>get</code> method.
     */
    public abstract Object construct();
    /**
     * Called on the event dispatching thread (not on the worker thread)
     * after the <code>construct</code> method has returned.
     */
    public void finished() {
    }
    /**
     * A new method that interrupts the worker thread.  Call this method
     * to force the worker to stop what it's doing.
     */
    public void interrupt() {
        Thread t = threadVar.get();
        if (t != null) {
            t.interrupt();
        }
        threadVar.clear();
    }
    /**
     * Return the value created by the <code>construct</code> method.
     * Returns null if either the constructing thread or the current
     * thread was interrupted before a value was produced.
     *
     * @return the value created by the <code>construct</code> method
     */
    public Object get() {
        while (true) {
            Thread t = threadVar.get();
            if (t == null) {
                return getValue();
            }
            try {
                t.join();
            }
            catch (InterruptedException e) {
                Thread.currentThread().interrupt(); // propagate
                return null;
            }
        }
    }
    /**
     * Start a thread that will call the <code>construct</code> method
     * and then exit.
     */
    public SwingWorker() {
        final Runnable doFinished = new Runnable() {
           public void run() { finished(); }
        };
        Runnable doConstruct = new Runnable() {
            public void run() {
                try {
                    setValue(construct());
                }
                finally {
                    threadVar.clear();
                }
                SwingUtilities.invokeLater(doFinished);
            }
        };
        Thread t = new Thread(doConstruct);
        threadVar = new ThreadVar(t);
    }
    /**
     * Start the worker thread.
     */
    public void start() {
        Thread t = threadVar.get();
        if (t != null) {
            t.start();
        }
    }
}