java - 我的 Swing 应用程序可能不是线程安全的 - 虽然不知道为什么

Question

应评论者的要求进行编辑。我希望这是合规的。

第一次发帖!试图理解为什么我的 Swing 应用程序不能从一个面板前进到下一个面板。这是代码的一般流程:

public class MainWindow {

JFrame mainFrame;
ChangeablePanel currentScreen; // abstract and extends JPanel, has getters &
setters for a Timer (swing timer), a String (nextScreen), and an Image 
(background image).  also has a close(AWTEvent e) method that simply calls 
"this.setVisible(false);"

public MainWindow() {
    mainFrame = new JFrame("New Arcana");
    mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       
    setTitleFrame();
} // MainFrame constructor

public void changeFrame(String frameType, String frameName) {               
    switch (frameType) {
        case "Title":
            setTitleFrame();
            break;
        case "Town":
            setTownFrame(frameName);
            break;
        case "Movie":
            setMovieFrame(frameName);               
            break;
        default:
            break;
    } // switch     
} // changeFrame

private void setTitleFrame() {      
    currentScreen = new TitlePanel();
    currentScreen.addComponentListener(new ScreenChangeListener());
    ...             
    mainFrame.setContentPane(currentScreen);
    mainFrame.setSize(titleScreenLength, titleScreenHeight); // put constants here if you want
    mainFrame.setLocationRelativeTo(null);
    mainFrame.setVisible(true);
} // setTitleFrame

private void setTownFrame(String townName) {        
    currentScreen = new TownPanel(townName);
    currentScreen.addComponentListener(new ScreenChangeListener());
    ...     
    mainFrame.setContentPane(currentScreen);        
    mainFrame.setSize(townScreenLength, townScreenHeight); // put constants here if you want
    mainFrame.setVisible(true);     
} // setTownFrame

private void setMovieFrame(String movieName) {      
    currentScreen = new MoviePanel(movieName);
    currentScreen.addComponentListener(new ScreenChangeListener());
    ...
    mainFrame.setContentPane(currentScreen);
    mainFrame.setSize(titleScreenLength, titleScreenHeight); // put constants here if you want      
    mainFrame.setVisible(true);     
} // setMovieFrame

private class ScreenChangeListener implements ComponentListener {
    @Override
    public void componentHidden(ComponentEvent e) {
        gotoNextScreen(e);
    }

    public void componentMoved(ComponentEvent e) {}

    public void componentResized(ComponentEvent e) {}

    public void componentShown(ComponentEvent e) {}     
} // ScreenChangeListener

public void gotoNextScreen(ComponentEvent e) {        
    changeFrame(currentScreen.getNextScreen(), null);   
}
} // MainWindow

public class Start {
...
public static void main(String[] args) {
    initialize();   

    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            new MainWindow();
        }
    });   
} // main
...
} // Start

public class TitlePanel extends ChangeablePanel implements ActionListener {

JButton newGame, continueGame;

public TitlePanel() {       
    setFocusable(true);     
    ...

    newGame = new JButton("New Game");
    continueGame = new JButton("Continue");     

    newGame.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            setNextScreen("Movie");
            close(e);               
        }       
    });

    add(newGame);
    add(continueGame);

    createTimer(10, this);
    getTimer().start();
} // TitlePanel constructor

@Override
public void actionPerformed(ActionEvent e) {
    repaint();      
}

public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D) g;        
    drawTitleScreen(g2d);       
} // paintComponent

private void drawTitleScreen(Graphics2D g2d) {
    g2d.drawImage(getBGImage(), 0, 0, null);
    newGame.setLocation(170, 550);
    continueGame.setLocation(605, 550);
} // drawTitleScreen
} // TitlePanel

public class MoviePanel extends ChangeablePanel implements ActionListener { 

public MoviePanel(String movieName) {       
    setFocusable(true); 

    addKeyListener(new AnyKeyActionListener());
    ...
    createTimer(10, this);
    getTimer().start();
} // TitlePanel constructor

@Override
public void actionPerformed(ActionEvent e) {
    repaint();
}

public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;        
    drawMovie(g2d);     
} // paintComponent 

private void drawMovie(Graphics2D g2d) {
    g2d.drawImage(getBGImage(), 0, 0, null);        
} // drawTitleScreen    

private class AnyKeyActionListener extends KeyAdapter {     
    public void keyTyped(KeyEvent e) {
        setNextScreen("Town");
        close(e);
    } // keyPressed     
} // listener to check for keystrokes   
} // MoviePanel

随着应用程序基于用户输入的推进，MainFrame 将填充更多的帧(目前，只有 MoviePanel 和 TownPanel 被编码)，它们的代码与这个非常相似——我也粘贴了 MoviePanel。

执行在上面基于 KeyAdapter 的监听器之后中断。但是，当我在带有断点的 Eclipse 中以 Debug模式运行我的应用程序时，这确实完成了它应该做的事情并从 MoviePanel 前进到 TownPanel。正因为如此，我怀疑线程是这里的罪魁祸首。请注意，我确实在上面的代码块上尝试了 SwingUtilities.invokeLater() 技术的许多不同组合，但它没有改变任何东西。任何帮助，将不胜感激;谢谢!

Answer 1

执行以下操作:

• invokeLater 用于在 GUI 事件调度线程上创建
• 在构建过程中没有 repaint()
• 最后设置可见

特别是在事件监听器上再次使用 invokeLater，让按钮等响应，然后采取响应的 Action 。

public static void main(String[] args) {
    ...
    SwingUtilities.invokeLater() {
        @Override()
        new Runnable() {
            new MainFrame().setVisible(true);
        }
    };        
}

---

代码审查

在 TitlePanel.TitlePanel 中最好使用绝对布局(即 null)，而不是在绘制代码中使用 setLocation。

    setLayout(null);
    newGame = new JButton("New Game");
    continueGame = new JButton("Continue");
    newGame.setBounds(170, 550, 120, 24);
    continueGame.setBounds(605, 550, 120, 24);

在 ChangeablePanel.close 中也确保 timer.stop()。

在 MainWindow 中使用 invokeLater:

public void gotoNextScreen(ComponentEvent e) {
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            changeFrame(currentScreen.getNextScreen(), null);
        }
    });   
}

在 MoviePanel 中 我看不到 addKeyListener 可以运行；也许遗漏的代码？或者这可能是您看到的错误？此外，我发现一个简单的 repaint() 可疑；会期待这样的事情:

public void actionPerformed(ActionEvent e) {
    invalidate();
    repaint(10L);
}