CompoundEdit: canUndo() : CompoundEdit « javax.swing.undo « Java by API

1. Java by API
2. javax.swing.undo
3. CompoundEdit

CompoundEdit: canUndo()

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

import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JRadioButton;
import javax.swing.JToggleButton;
import javax.swing.undo.AbstractUndoableEdit;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.CompoundEdit;
import javax.swing.undo.UndoableEdit;

public class UndoableToggleApp2 extends JFrame {

  private CompoundEdit edit;

  private JButton undoButton = new JButton("Undo");

  private JButton redoButton = new JButton("Redo");

  private JButton endButton = new JButton("End");

  public UndoableToggleApp2() {
    JToggleButton tog = new JToggleButton("ToggleButton");
    JCheckBox cb = new JCheckBox("CompoundEdit ExampleCheckBox");
    JRadioButton radio = new JRadioButton("RadioButton");

    SimpleListener sl = new SimpleListener();
    tog.addActionListener(sl);
    cb.addActionListener(sl);
    radio.addActionListener(sl);

    Box buttonBox = new Box(BoxLayout.Y_AXIS);
    buttonBox.add(tog);
    buttonBox.add(cb);
    buttonBox.add(radio);
    
    undoButton.setEnabled(false);
    redoButton.setEnabled(false);
    endButton.setEnabled(false);

    undoButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ev) {
        try {
          edit.undo();
        } catch (CannotUndoException ex) {
          ex.printStackTrace();
        } finally {
          undoButton.setEnabled(edit.canUndo());
          redoButton.setEnabled(edit.canRedo());
        }
      }
    });

    redoButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ev) {
        try {
          edit.redo();
        } catch (CannotRedoException ex) {
          ex.printStackTrace();
        } finally {
          undoButton.setEnabled(edit.canUndo());
          redoButton.setEnabled(edit.canRedo());
        }
      }
    });

    endButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ev) {
        edit.end();
        endButton.setEnabled(false);
        undoButton.setEnabled(edit.canUndo());
        redoButton.setEnabled(edit.canRedo());
      }
    });

    Box undoRedoEndBox = new Box(BoxLayout.X_AXIS);
    undoRedoEndBox.add(Box.createGlue());
    undoRedoEndBox.add(undoButton);
    undoRedoEndBox.add(Box.createHorizontalStrut(2));
    undoRedoEndBox.add(redoButton);
    undoRedoEndBox.add(Box.createHorizontalStrut(2));
    undoRedoEndBox.add(endButton);
    undoRedoEndBox.add(Box.createGlue());

    Container content = getContentPane();
    content.setLayout(new BorderLayout());
    content.add(buttonBox, BorderLayout.CENTER);
    content.add(undoRedoEndBox, BorderLayout.SOUTH);
    setSize(400, 150);
  }

  public class SimpleListener implements ActionListener {
    public void actionPerformed(ActionEvent ev) {
      if (edit == null || edit.isInProgress() == false)
        edit = new CompoundEdit();

      JToggleButton tb = (JToggleButton) ev.getSource();
      UndoableEdit togEdit = new UndoableToggleEdit(tb);
      edit.addEdit(togEdit);
      endButton.setEnabled(true);
      undoButton.setEnabled(edit.canUndo());
      redoButton.setEnabled(edit.canRedo());
    }
  }

  // Main program just creates the frame and displays it.
  public static void main(String[] args) {
    JFrame f = new UndoableToggleApp2();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
  }
}

class UndoableToggleEdit extends AbstractUndoableEdit {

  private JToggleButton button;

  private boolean selected;

  // Create a new edit for a JToggleButton that has just been toggled.
  public UndoableToggleEdit(JToggleButton button) {
    this.button = button;
    selected = button.isSelected();
  }

  // Return a reasonable name for this edit.
  public String getPresentationName() {
    return "Toggle " + button.getText() + " " + (selected ? "on" : "off");
  }

  // Redo by setting the button state as it was initially.
  public void redo() throws CannotRedoException {
    super.redo();
    button.setSelected(selected);
  }

  // Undo by setting the button state to the opposite value.
  public void undo() throws CannotUndoException {
    super.undo();
    button.setSelected(!selected);
  }
}

           
       

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