Question

我正在从一本书中学习面向对象的编程。我走得很远，但现在我被卡住了。 wExec重新执行了吗？我不确定这是否可行。有人可以为我清除这一点。当我按下“完成”按钮并退出执行参考对象时，我很困惑。这是每个代码类：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class RunApp {
    public static void main(String[] args) {
        MainApp app = new MainApp("hello world");
        app.showApp();
    }
}

class MainApp extends MmvcApp {
    WmvcButton btnDone;
    WmvcButton btnExit;

    public MainApp(String title) {
        super(title);
        btnDone = new WmvcButton("Done", new WmvcExecutor() {
            public void execute(ActionEvent event) {
                System.out.println("done");
                System.out.println("test 2");
            }
        });

        btnExit = new WmvcButton("Exit", btnDone.getExecutor());

    }
}

abstract class MmvcApp {
    private static JFrame frame;
    private static JPanel panel;
    private static MmvcApp singletonApp = null;

    public MmvcApp(String frameText) {
        singletonApp = this;
        initializeApp(frameText);
    }

    public void initializeApp(String frameText) {
        frame = new JFrame(frameText);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        panel = new JPanel();
        panel.setPreferredSize(new Dimension(400, 300));
        frame.add(panel, BorderLayout.CENTER);
    }

    public static JFrame getFrame() {
        return frame;
    }

    public static JPanel getPanel() {
        return panel;
    }

    public static MmvcApp getApp() {
        return singletonApp;
    }

    public void showApp() {
        frame.pack();
        frame.setVisible(true);
    }
}

class WmvcButton extends WmvcController {
    private JButton myButton;

    public WmvcButton(String compText, WmvcExecutor wExec) {
        super((JComponent) new JButton(), wExec);

        myButton = (JButton) myComponent;

        myButton.setText(compText);
        myButton.addActionListener(this);
        MmvcApp.getPanel().add(myButton);
    }
}

class WmvcController implements ActionListener {
    public JComponent myComponent;
    private WmvcExecutor wExec;

    public WmvcController(JComponent component, WmvcExecutor wExec) {
        myComponent = component;
        this.wExec = wExec;
    }

    public WmvcExecutor getExecutor() {
        return wExec;
    }

    public void actionPerformed(ActionEvent event) {
        if (wExec != null) {
            wExec.execute(event);
            System.out.println("test 1");
        } else
            System.out.println("not working ");
    }
}

class WmvcExecutor {
    public void execute(ActionEvent event) {
    }
}

Answer 1

btnDone和btnExit都与WmvncExecuter具有相同的引用。在这一行：

btnDone = new WmvcButton("Done", new WmvcExecutor() {
    public void execute(ActionEvent event) {
        System.out.println("done");
        System.out.println("test 2");
    }
});
btnExit = new WmvcButton("Exit", btnDone.getExecutor());

您正在覆盖execute()方法。这与制作一个新课程并在那里重写一样。

class WmvcExecuterTest extends WmvcExecuter{
    public void execute(ActionEvent event){
        System.out.println("done");
    }
}

因此，当您从普通execute()拨打WmvnExecuter时，它不会执行任何操作，但是因为您覆盖了execute()。只要从该特定实例调用execute()，它就会执行新代码。

事件对象会发生什么？它是否重新执行代码？

1 个答案: