UndoEditor.java Source code

Introduction

Here is the source code for UndoEditor.java

Source

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

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.UndoManager;

public class UndoEditor extends JFrame {
    private UndoManager undoManager = new UndoManager();
    private JMenuBar menuBar = new JMenuBar();
    private JMenu editMenu = new JMenu("Edit");
    private UndoAction undoAction = new UndoAction();
    private RedoAction redoAction = new RedoAction();

    public UndoEditor() {
        setLayout(new BorderLayout());
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTextPane editor = new JTextPane();
        editor.getDocument().addUndoableEditListener(new UndoListener());

        JScrollPane scroller = new JScrollPane(editor);
        menuBar.add(editMenu);
        editMenu.add(undoAction);
        editMenu.add(redoAction);
        this.setJMenuBar(menuBar);
        add(scroller);
        setSize(400, 300);
        setVisible(true);
    }

    public static void main(String[] args) {
        new UndoEditor();
    }

    class UndoListener implements UndoableEditListener {
        public void undoableEditHappened(UndoableEditEvent e) {
            undoManager.addEdit(e.getEdit());
            undoAction.update();
            redoAction.update();
        }
    }

    class UndoAction extends AbstractAction {
        public UndoAction() {
            this.putValue(Action.NAME, undoManager.getUndoPresentationName());
            this.setEnabled(false);
        }

        public void actionPerformed(ActionEvent e) {
            if (this.isEnabled()) {
                undoManager.undo();
                undoAction.update();
                redoAction.update();
            }
        }

        public void update() {
            this.putValue(Action.NAME, undoManager.getUndoPresentationName());
            this.setEnabled(undoManager.canUndo());
        }
    }

    class RedoAction extends AbstractAction {
        public RedoAction() {
            this.putValue(Action.NAME, undoManager.getRedoPresentationName());
            this.setEnabled(false);
        }

        public void actionPerformed(ActionEvent e) {
            if (this.isEnabled()) {
                undoManager.redo();
                undoAction.update();
                redoAction.update();
            }
        }

        public void update() {
            this.putValue(Action.NAME, undoManager.getRedoPresentationName());
            this.setEnabled(undoManager.canRedo());
        }
    }
}