使用不可变对象撤消/重做

def undo():
    try:
        redo()
    except Exception as e:
        print("Error while undoing: ", e)

def redo():
    try:
        undo()
    except Exception as e:
        print("Error while redoing: ", e)

import javax.swing.undo.*;

public class UndoExample {
    public static void main(String[] args) {
        javax.swing.JTextArea textArea = new javax.swing.JTextArea();
        textArea.setText("Hello, world!");

        javax.swing.undo.UndoManager undoManager = new javax.swing.undo.UndoManager();
        javax.swing.undo.UndoableEditListener listener = new javax.swing.undo.UndoableEditListener() {
            public void undoableEditHappened(javax.swing.undo.UndoableEditEvent e) {
                System.out.println("Undoable edit occurred: " + e.getEdit());
            }
        };
        textArea.getDocument().addUndoableEditListener(listener);

        // 撤销和重做操作
        undoManager.undo();
        System.out.println("Undo level: " + undoManager.getUndoLevel());
        undoManager.redo();
        System.out.println("Redo level: " + undoManager.getRedoLevel());

        // 移除撤销和重做事件监听器
        textArea.getDocument().removeUndoableEditListener(listener);
    }
}