Demonstrates how to add copy and drag support to a Swing component with TransferHandler : Drag Drop « Swing « Java Tutorial

/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.text.DateFormat;
import java.util.Date;

import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JLabel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.TransferHandler;
import javax.swing.border.LineBorder;

/**
 * A custom Swing component that displays a simple digital clock. Demonstrates
 * how to add copy and drag support to a Swing component with TransferHandler.
 */
public class DigitalClock extends JLabel {
  DateFormat format; // How to display the time in string form

  int updateFrequency; // How often to update the time (in milliseconds)

  Timer timer; // Triggers repeated updates to the clock

  public DigitalClock() {
    // Set default values for our properties
    setFormat(DateFormat.getTimeInstance(DateFormat.MEDIUM, getLocale()));
    setUpdateFrequency(1000); // Update once a second

    // Specify a Swing TransferHandler object to do the dirty work of
    // copy-and-paste and drag-and-drop for us. This one will transfer
    // the value of the "time" property. Since this property is read-only
    // it will allow drags but not drops.
    setTransferHandler(new TransferHandler("time"));

    // Since JLabel does not normally support drag-and-drop, we need an
    // event handler to detect a drag and start the transfer.
    addMouseMotionListener(new MouseMotionAdapter() {
      public void mouseDragged(MouseEvent e) {
        getTransferHandler().exportAsDrag(DigitalClock.this, e, TransferHandler.COPY);
      }
    });

    // Before we can have a keyboard binding for a Copy command,
    // the component needs to be able to accept keyboard focus.
    setFocusable(true);
    // Request focus when we're clicked on
    addMouseListener(new MouseAdapter() {
      public void mouseClicked(MouseEvent e) {
        requestFocus();
      }
    });
    // Use a LineBorder to indicate when we've got the keyboard focus
    addFocusListener(new FocusListener() {
      public void focusGained(FocusEvent e) {
        setBorder(LineBorder.createBlackLineBorder());
      }

      public void focusLost(FocusEvent e) {
        setBorder(null);
      }
    });

    // Now bind the Ctrl-C keystroke to a "Copy" command.
    InputMap im = new InputMap();
    im.setParent(getInputMap(WHEN_FOCUSED));
    im.put(KeyStroke.getKeyStroke(KeyEvent.VK_C, InputEvent.CTRL_MASK), "Copy");
    setInputMap(WHEN_FOCUSED, im);

    // And bind the "Copy" command to a pre-defined Action that performs
    // a copy using the TransferHandler we've installed.
    ActionMap am = new ActionMap();
    am.setParent(getActionMap());
    am.put("Copy", TransferHandler.getCopyAction());
    setActionMap(am);

    // Create a javax.swing.Timer object that will generate ActionEvents
    // to tell us when to update the displayed time. Every updateFrequency
    // milliseconds, this timer will cause the actionPerformed() method
    // to be invoked. (For non-GUI applications, see java.util.Timer.)
    timer = new Timer(updateFrequency, new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        setText(getTime()); // set label to current time string
      }
    });
    timer.setInitialDelay(0); // Do the first update immediately
    timer.start(); // Start timing now!
  }

  // Return the current time as a String.
  // This is the property accessor method used by the TransferHandler.
  // Since there is a getter, but no setter, the TransferHandler will
  // reject any attempts to drop data on us.
  public String getTime() {
    // Use the DateFormat object to convert current time to a string
    return format.format(new Date());
  }

  // Here are two related property setter methods
  public void setFormat(DateFormat format) {
    this.format = format;
  }

  public void setUpdateFrequency(int ms) {
    this.updateFrequency = ms;
  }
}

14.112.Drag Drop
	14.112.1.	Basic drag and drop
	14.112.2.	Dragging Text from a JLabel
	14.112.3.	Drag-and-Drop Support for Images
	14.112.4.	Drag and drop icons: use an icon property.
	14.112.5.	implements DragGestureListener, Transferable
	14.112.6.	Dragging and dropping text between a text area, a list, and a table
	14.112.7.	Drag and drop between JTextArea and JTextField
	14.112.8.	Transfer both Text and Color between JTextField and JTextArea
	14.112.9.	Drag and drop between JList and JTextField
	14.112.10.	DropMode.ON
	14.112.11.	DropMode.INSERT
	14.112.12.	DropMode.ON_OR_INSERT
	14.112.13.	Set tree DropMode to DropMode.USE_SELECTION
	14.112.14.	Set tree drag mode to DropMode.ON
	14.112.15.	Set tree drag mode to DropMode.INSERT
	14.112.16.	Set tree drag mode to DropMode.ON_OR_INSERT
	14.112.17.	Choose Drop Action
	14.112.18.	Various drop actions
	14.112.19.	JTable drag and drop
	14.112.20.	Create a drag source a drop target and a transferable object.
	14.112.21.	Making a Component Draggable
	14.112.22.	Detect a drag initiating gesture in your application
	14.112.23.	Illustrates cut, copy, paste and drag and drop using three instances of JList
	14.112.24.	Location sensitive drag and drop
	14.112.25.	Demonstration of the top-level TransferHandler support on JFrame
	14.112.26.	Drag-and-Drop customization: drag the foreground color from the first label and drop it as the background color into the second one
	14.112.27.	Demonstrates how to add copy and drag support to a Swing component with TransferHandler
	14.112.28.	ScribblePane allows individual PolyLine lines to be selected, cut, copied, pasted, dragged, and dropped
	14.112.29.	Built-in drag and drop support: utilize a TransferHandler class
	14.112.30.	DND Drag and drop List