UndoDemo.java Source code

Introduction

Here is the source code for UndoDemo.java

Source

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.undo.UndoManager;

/**
 * Simple GUI demo of UndoManager and friends.
 * 
 * @author Ian Darwin http://www.darwinsys.com/
 */
public class UndoDemo extends JFrame {

    JTextArea ta;

    UndoManager um;

    /** Simple main program that just constructs and shows the GUI */
    public static void main(String[] files) {
        new UndoDemo().setVisible(true);
    }

    /** Construct a GUI that demonstrates use of UndoManager */
    public UndoDemo() {

        Container cp = getContentPane();
        cp.add(ta = new JTextArea(20, 60), BorderLayout.CENTER);
        JPanel bp;
        cp.add(bp = new JPanel(), BorderLayout.SOUTH);

        // Create a javax.swing.undo.UndoManager; this is an amazing class that
        // keeps a Stack of UndoableEdits and lets you invoke them;
        // by registering it as a Listener on the TextComponent.Document,
        // the Document will create the UndoableEdit objects and send them
        // to the UndoManager. Between them they do ALL the work!
        um = new UndoManager();
        ta.getDocument().addUndoableEditListener(um);

        // Create the buttons
        JButton cutButton, copyButton, pasteButton, undoButton, redoButton;
        bp.add(cutButton = new JButton("Cut"));
        cutButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                ta.cut();
            }
        });

        bp.add(copyButton = new JButton("Copy"));
        copyButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                ta.copy();
            }
        });

        bp.add(pasteButton = new JButton("Paste"));
        pasteButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                ta.paste();
            }
        });
        bp.add(undoButton = new JButton("UnDo"));
        undoButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (um.canUndo()) {
                    um.undo();
                } else {
                    warn("Can't undo");
                }
            }
        });
        bp.add(redoButton = new JButton("ReDo"));
        redoButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (um.canRedo()) {
                    um.redo();
                } else {
                    warn("Can't redo");
                }
            }
        });
        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    void warn(String msg) {
        JOptionPane.showMessageDialog(this, "Warning: " + msg, "Warning", JOptionPane.WARNING_MESSAGE);
    }
}