如何在JTextArea中实现撤消功能

[xsjohn]

如何在JTextArea中实现撤消功能，JTextArea是否有现成的方法可以调用？求教大人~~

[mq612]

你要的是Undo和Redo吧？
真正操控Undo、Redo功能的是Document，下面写个小例子，希望对你有帮助：

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.event.UndoableEditEvent;
import javax.swing.text.Document;
import javax.swing.undo.UndoManager;

public class Test extends JFrame {

private static final long serialVersionUID = -2397593626990759111L;

private JPanel pane = null;

private JButton undo = null, redo = null;

private JScrollPane sPane = null;

private JTextArea text = null;

private Document doc = null;

private UndoManager undomang = null;

public Test() {
super("Redo and Undo");
undomang = new UndoManager(){
private static final long serialVersionUID = -5960092671497318496L;
public void undoableEditHappened(UndoableEditEvent e) {
this.addEdit(e.getEdit());
}
};
text = new JTextArea();
doc = text.getDocument();
redo = new JButton(">>");
undo = new JButton("<<");
undo.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
if (undomang.canUndo())
undomang.undo();
}
});
redo.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (undomang.canRedo())
undomang.redo();
}
});
pane = new JPanel();
pane.add(undo);
pane.add(redo);
doc.addUndoableEditListener(undomang);
sPane = new JScrollPane(text);
this.getContentPane().add(sPane);
this.getContentPane().add(pane, BorderLayout.NORTH);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(300, 200);
this.setVisible(true);
}

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

}