Java Tutorial/Swing/Redo Undo

14. Adding Undo and Redo to a Text Component

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
public class Main{
public static void main(String[] argv) throws Exception{
    JTextComponent textcomp = new JTextArea();
    final UndoManager undo = new UndoManager();
    Document doc = textcomp.getDocument();
    JFrame f = new JFrame();
    f.add(new JScrollPane(textcomp));
    f.setSize(330,300);
    f.setVisible(true);
    
    doc.addUndoableEditListener(new UndoableEditListener() {
        public void undoableEditHappened(UndoableEditEvent evt) {
            undo.addEdit(evt.getEdit());
        }
    });
    
    textcomp.getActionMap().put("Undo",
        new AbstractAction("Undo") {
            public void actionPerformed(ActionEvent evt) {
                try {
                    if (undo.canUndo()) {
                        undo.undo();
                    }
                } catch (CannotUndoException e) {
                }
            }
       });
    
    textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
    
    textcomp.getActionMap().put("Redo",
        new AbstractAction("Redo") {
            public void actionPerformed(ActionEvent evt) {
                try {
                    if (undo.canRedo()) {
                        undo.redo();
                    }
                } catch (CannotRedoException e) {
                }
            }
        });
    
    textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Y"), "Redo");
}}

14. Bind the undo action to ctl-Z

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
public class Main {
  public static void main(String[] argv) {
    JTextComponent textcomp = new JTextArea();
    final UndoManager undo = new UndoManager();
    Document doc = textcomp.getDocument();
    doc.addUndoableEditListener(new UndoableEditListener() {
      public void undoableEditHappened(UndoableEditEvent evt) {
        undo.addEdit(evt.getEdit());
      }
    });
    textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
      public void actionPerformed(ActionEvent evt) {
        try {
          if (undo.canUndo()) {
            undo.undo();
          }
        } catch (CannotUndoException e) {
        }
      }
    });
    textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new JScrollPane(textcomp));
    frame.setSize(380, 320);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

14. Create an undo action and add it to the text component

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
public class Main {
  public static void main(String[] argv) {
    JTextComponent textcomp = new JTextArea();
    final UndoManager undo = new UndoManager();
    Document doc = textcomp.getDocument();
    doc.addUndoableEditListener(new UndoableEditListener() {
      public void undoableEditHappened(UndoableEditEvent evt) {
        undo.addEdit(evt.getEdit());
      }
    });
    textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
      public void actionPerformed(ActionEvent evt) {
        try {
          if (undo.canUndo()) {
            undo.undo();
          }
        } catch (CannotUndoException e) {
        }
      }
    });
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new JScrollPane(textcomp));
    frame.setSize(380, 320);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

14. Create a redo action and add it to the text component (JTextComponent)

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
public class Main {
  public static void main(String[] argv) {
    JTextComponent textcomp = new JTextArea();
    final UndoManager undo = new UndoManager();
    Document doc = textcomp.getDocument();
    doc.addUndoableEditListener(new UndoableEditListener() {
      public void undoableEditHappened(UndoableEditEvent evt) {
        undo.addEdit(evt.getEdit());
      }
    });
    textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
      public void actionPerformed(ActionEvent evt) {
        try {
          if (undo.canUndo()) {
            undo.undo();
          }
        } catch (CannotUndoException e) {
        }
      }
    });
    textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
    textcomp.getActionMap().put("Redo", new AbstractAction("Redo") {
      public void actionPerformed(ActionEvent evt) {
        try {
          if (undo.canRedo()) {
            undo.redo();
          }
        } catch (CannotRedoException e) {
        }
      }
    });
    textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Y"), "Redo");
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new JScrollPane(textcomp));
    frame.setSize(380, 320);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

14. Listen for undo and redo events

public class Main{
public static void main(String[] argv){
    JTextComponent textcomp = new JTextArea();
    final UndoManager undo = new UndoManager();
    Document doc = textcomp.getDocument();
    
    doc.addUndoableEditListener(new UndoableEditListener() {
        public void undoableEditHappened(UndoableEditEvent evt) {
            undo.addEdit(evt.getEdit());
        }
    });    
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new JScrollPane(textcomp));
    frame.setSize(380, 320);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}}

14. Undoable Drawing

import java.awt.BorderLayout;
import java.awt.ruponent;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Hashtable;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JToolBar;
import javax.swing.UIManager;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.StateEdit;
import javax.swing.undo.StateEditable;
import javax.swing.undo.UndoManager;
import javax.swing.undo.UndoableEditSupport;
public class UndoableDrawingPanel extends JPanel implements StateEditable {
  private static String POLYGON_KEY = "Polygon";
  UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);
  Polygon polygon = new Polygon();
  public UndoableDrawingPanel() {
    MouseListener mouseListener = new MouseAdapter() {
      public void mouseReleased(MouseEvent mouseEvent) {
        StateEdit stateEdit = new StateEdit(UndoableDrawingPanel.this);
        polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());
        stateEdit.end();
        undoableEditSupport.postEdit(stateEdit);
        repaint();
      }
    };
    addMouseListener(mouseListener);
  }
  public void addUndoableEditListener(UndoableEditListener undoableEditListener) {
    undoableEditSupport.addUndoableEditListener(undoableEditListener);
  }
  public void removeUndoableEditListener(UndoableEditListener undoableEditListener) {
    undoableEditSupport.removeUndoableEditListener(undoableEditListener);
  }
  public void storeState(Hashtable state) {
    state.put(POLYGON_KEY, getPolygon());
  }
  public void restoreState(Hashtable state) {
    Polygon polygon = (Polygon) state.get(POLYGON_KEY);
    if (polygon != null) {
      setPolygon(polygon);
    }
  }
  public void setPolygon(Polygon newValue) {
    polygon = newValue;
    repaint();
  }
  public Polygon getPolygon() {
    Polygon returnValue;
    if (polygon.npoints == 0) {
      returnValue = new Polygon();
    } else {
      returnValue = new Polygon(polygon.xpoints, polygon.ypoints, polygon.npoints);
    }
    return returnValue;
  }
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.drawPolygon(polygon);
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("Drawing Sample2");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    UndoableDrawingPanel drawingPanel = new UndoableDrawingPanel();
    UndoManager manager = new UndoManager();
    drawingPanel.addUndoableEditListener(manager);
    JToolBar toolbar = new JToolBar();
    JButton undoButton = new JButton(UndoManagerHelper.getUndoAction(manager));
    toolbar.add(undoButton);
    JButton redoButton = new JButton(UndoManagerHelper.getRedoAction(manager));
    toolbar.add(redoButton);
    frame.add(toolbar, BorderLayout.NORTH);
    frame.add(drawingPanel, BorderLayout.CENTER);
    frame.setSize(300, 150);
    frame.setVisible(true);
  }
}
class UndoManagerHelper {
  public static Action getUndoAction(UndoManager manager, String label) {
    return new UndoAction(manager, label);
  }
  public static Action getUndoAction(UndoManager manager) {
    return new UndoAction(manager, (String) UIManager.get("AbstractUndoableEdit.undoText"));
  }
  public static Action getRedoAction(UndoManager manager, String label) {
    return new RedoAction(manager, label);
  }
  public static Action getRedoAction(UndoManager manager) {
    return new RedoAction(manager, (String) UIManager.get("AbstractUndoableEdit.redoText"));
  }
  private abstract static class UndoRedoAction extends AbstractAction {
    UndoManager undoManager = new UndoManager();
    String errorMessage = "Cannot undo";
    String errorTitle = "Undo Problem";
    protected UndoRedoAction(UndoManager manager, String name) {
      super(name);
      undoManager = manager;
    }
    public void setErrorMessage(String newValue) {
      errorMessage = newValue;
    }
    public void setErrorTitle(String newValue) {
      errorTitle = newValue;
    }
    protected void showMessage(Object source) {
      if (source instanceof Component) {
        JOptionPane.showMessageDialog((Component) source, errorMessage, errorTitle,
            JOptionPane.WARNING_MESSAGE);
      } else {
        System.err.println(errorMessage);
      }
    }
  }
  public static class UndoAction extends UndoRedoAction {
    public UndoAction(UndoManager manager, String name) {
      super(manager, name);
      setErrorMessage("Cannot undo");
      setErrorTitle("Undo Problem");
    }
    public void actionPerformed(ActionEvent actionEvent) {
      try {
        undoManager.undo();
      } catch (CannotUndoException cannotUndoException) {
        showMessage(actionEvent.getSource());
      }
    }
  }
  public static class RedoAction extends UndoRedoAction {
    public RedoAction(UndoManager manager, String name) {
      super(manager, name);
      setErrorMessage("Cannot redo");
      setErrorTitle("Redo Problem");
    }
    public void actionPerformed(ActionEvent actionEvent) {
      try {
        undoManager.redo();
      } catch (CannotRedoException cannotRedoException) {
        showMessage(actionEvent.getSource());
      }
    }
  }
}

14. Undo Editor

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());
    }
  }
}

14. Using the Undo Framework with Swing Text Components

import java.awt.BorderLayout;
import java.awt.ruponent;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JToolBar;
import javax.swing.UIManager;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
class UndoManagerHelper {
  public static Action getUndoAction(UndoManager manager, String label) {
    return new UndoAction(manager, label);
  }
  public static Action getUndoAction(UndoManager manager) {
    return new UndoAction(manager, (String) UIManager.get("AbstractUndoableEdit.undoText"));
  }
  public static Action getRedoAction(UndoManager manager, String label) {
    return new RedoAction(manager, label);
  }
  public static Action getRedoAction(UndoManager manager) {
    return new RedoAction(manager, (String) UIManager.get("AbstractUndoableEdit.redoText"));
  }
  private abstract static class UndoRedoAction extends AbstractAction {
    UndoManager undoManager = new UndoManager();
    String errorMessage = "Cannot undo";
    String errorTitle = "Undo Problem";
    protected UndoRedoAction(UndoManager manager, String name) {
      super(name);
      undoManager = manager;
    }
    public void setErrorMessage(String newValue) {
      errorMessage = newValue;
    }
    public void setErrorTitle(String newValue) {
      errorTitle = newValue;
    }
    protected void showMessage(Object source) {
      if (source instanceof Component) {
        JOptionPane.showMessageDialog((Component) source, errorMessage, errorTitle,
            JOptionPane.WARNING_MESSAGE);
      } else {
        System.err.println(errorMessage);
      }
    }
  }
  public static class UndoAction extends UndoRedoAction {
    public UndoAction(UndoManager manager, String name) {
      super(manager, name);
      setErrorMessage("Cannot undo");
      setErrorTitle("Undo Problem");
    }
    public void actionPerformed(ActionEvent actionEvent) {
      try {
        undoManager.undo();
      } catch (CannotUndoException cannotUndoException) {
        showMessage(actionEvent.getSource());
      }
    }
  }
  public static class RedoAction extends UndoRedoAction {
    public RedoAction(UndoManager manager, String name) {
      super(manager, name);
      setErrorMessage("Cannot redo");
      setErrorTitle("Redo Problem");
    }
    public void actionPerformed(ActionEvent actionEvent) {
      try {
        undoManager.redo();
      } catch (CannotRedoException cannotRedoException) {
        showMessage(actionEvent.getSource());
      }
    }
  }
}
public class UndoSample {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Undo Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextArea textArea = new JTextArea();
    JScrollPane scrollPane = new JScrollPane(textArea);
    UndoManager manager = new UndoManager();
    textArea.getDocument().addUndoableEditListener(manager);
    JToolBar toolbar = new JToolBar();
    JButton undoButton = new JButton(UndoManagerHelper.getUndoAction(manager));
    toolbar.add(undoButton);
    JButton redoButton = new JButton(UndoManagerHelper.getRedoAction(manager));
    toolbar.add(redoButton);
    frame.add(toolbar, BorderLayout.NORTH);
    frame.add(scrollPane, BorderLayout.CENTER);
    frame.setSize(300, 150);
    frame.setVisible(true);
  }
}