The type new ActionListener(){} must implement the inherited abstract method ActionListener.actionPerformed(ActionEvent)

这个错误通常出现在使用 Java Swing 编写 GUI 界面时，其中一个 ActionListener 没有实现 actionPerformed(ActionEvent) 方法。它是 ActionListener 接口中的抽象方法，必须被实现以响应事件。

要解决这个错误，可以在实现 ActionListener 接口的类中添加 actionPerformed(ActionEvent) 方法。例如：

class MyActionListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        // 处理事件的代码
    }
}

或者，使用匿名内部类的方式：

myButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        // 处理事件的代码
    }
});

确保在实现 ActionListener 接口时，方法签名与 actionPerformed(ActionEvent) 方法相同即可。

相关问题

The type WindowMenu must implement the inherited abstract method ActionListener.actionPerformed(ActionEvent)是什么意思

这个错误信息意味着您定义的类 WindowMenu 继承自一个抽象类，但是没有实现该抽象类中的所有抽象方法。在这种情况下，该错误信息指出，WindowMenu 没有实现 ActionListener 接口中的 actionPerformed(ActionEvent) 方法。

要解决这个问题，您需要在 WindowMenu 类中添加一个 actionPerformed(ActionEvent) 方法的实现。这个方法将根据您的具体需求，编写处理 ActionEvent 事件的代码。例如，您可以编写一个 actionPerformed(ActionEvent) 方法来响应用户在菜单中选择某个选项时所需执行的操作。

Modify the MyFrame class from the code above to extend View, w.In the constructor of MyFrame, the actionPerformed method of the ActionListener of the “Reset” button must call the resetClicked method of the controller c, and the actionPerformed method of the ActionListener of the “Undo” button must call the undoClicked method of the controller c. The controller c will then itself implement the actual meaning of the button clicks. Also move the setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) method call from the constructor of MyFrame to the constructor of View.

Here is the modified code:

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.JTextField;

public class MyFrame extends View {

    private Controller c;
    private JTextField textField;

    public MyFrame(Controller controller) {
        super();
        this.c = controller;
        textField = new JTextField(20);
        JButton resetButton = new JButton("Reset");
        resetButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                c.resetClicked();
            }
        });
        JButton undoButton = new JButton("Undo");
        undoButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                c.undoClicked();
            }
        });
        JPanel panel = new JPanel();
        panel.add(textField);
        panel.add(resetButton);
        panel.add(undoButton);
        add(panel, BorderLayout.CENTER);
        pack();
        setVisible(true);
    }

    @Override
    public void update(String text) {
        textField.setText(text);
    }

    @Override
    public void setDefaultCloseOperation() {
        super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

In this modified code, `MyFrame` extends `View` and implements the `update` method. The `Controller` instance is passed to the constructor of `MyFrame`. The `actionPerformed` method of the `ActionListener` of the "Reset" button calls the `resetClicked` method of the `Controller`, and the `actionPerformed` method of the `ActionListener` of the "Undo" button calls the `undoClicked` method of the `Controller`. The `setDefaultCloseOperation` method call has been moved to the constructor of `View`.