Java - 在 JTextField 中输入一些字母后，JFrame 一直卡住

Question

我不知道为什么我的 JFrame 在我在 JTextField“用户名”和“密码”中输入字母后一直卡住:/任何人都可以查看我的代码并告诉我原因并修复它吗？

public class Main 
{       
    public static void main(String [ ] args)
    {    
        LoginWindow loginframe = new LoginWindow();
        loginframe.setVisible(true);
        loginframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        loginframe.initialize();    
        while(true)
        {
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            loginframe.Repaint();
        }
    }
}

框架类:

public class LoginWindow extends JFrame implements MouseListener, KeyListener, MouseMotionListener{

    public LoginWindow(){
        setSize(806, 629);
        setResizable(false);
        setLayout(new BorderLayout());
        background = new JLabel(ResourceLoader.Iconload("/main_01.jpg"));
        background.setBounds(0, 0, 800, 600);
        add(background);            
        background.setLayout(null);
        Username = new JTextField("", 20);
        Username.setForeground(Color.WHITE);
        Username.setBounds(312, 433, 170, 40);
        Username.setFont(new Font("Impact", Font.BOLD, 25));
        Username.setBackground(Color.BLACK);
        Username.setBorder(BorderFactory.createMatteBorder(0, 0, 5, 0, Color.BLACK));
        background.add(Username);           
        Password = new JPasswordField("", 20);
        Password.setForeground(Color.WHITE);
        Password.setBounds(312, 489, 170, 40);
        Password.setBackground(Color.BLACK);
        Password.setBorder(BorderFactory.createMatteBorder(0, 0, 5, 0, Color.BLACK));
        Password.setFont(new Font("Serif", Font.BOLD, 25));
        background.add(Password);
    }

    public void initialize()
    {
        makestrat();    
        addKeyListener(this);
        requestFocus();
        addMouseListener(this);
        addMouseMotionListener(this);    
    }

    public void makestrat()
    {
        createBufferStrategy(2);
        strat = getBufferStrategy(); 
    }

    public void Repaint()
    {           
        //System.out.println(mouseX + " " + mouseY);
        Graphics g = strat.getDrawGraphics();
        paintComponents(g);
        Draw(g);
        g.dispose();            
        strat.show();
    }

    public void Update()
    {           
    }

    public void Draw(Graphics g)
    {
        if(((mouseX >= 499) && (mouseX <=  669)) && ((mouseY >= 433)&&( mouseY <= 530))){
            g.drawImage(ResourceLoader.ImageLoad("/login_02.jpg"), 502, 459, null);
        }else{
            g.drawImage(ResourceLoader.ImageLoad("/login_01.jpg"), 502, 459, null);
        }
    }

    private class thehandler implements ActionListener{

        @Override
        public void actionPerformed(ActionEvent event) {   

        }           
    }

    public void mouseMoved(MouseEvent event)
    {
        mouseY = event.getY()-26;
        mouseX = event.getX()-3;
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        PointerInfo a = MouseInfo.getPointerInfo();
        Point point = new Point(a.getLocation());
        SwingUtilities.convertPointFromScreen(point, e.getComponent());
        double mouseX = (int) point.getX();
        double mouseY = (int) point.getY(); 
        System.out.println("(ContainerPos) Mouse clicked! X: " + mouseX + " Y: " + mouseY);
    }

    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub          
    }

    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub          
    }

    @Override
    public void mousePressed(MouseEvent e) {            
    }

    @Override
    public void mouseReleased(MouseEvent e) {           
    }

    @Override
    public void keyPressed(KeyEvent arg0) {
        // TODO Auto-generated method stub          
    }

    @Override
    public void keyReleased(KeyEvent arg0) {
        // TODO Auto-generated method stub          
    }

    @Override
    public void keyTyped(KeyEvent arg0) {
        // TODO Auto-generated method stub          
    }

    @Override
    public void mouseDragged(MouseEvent arg0) {
        // TODO Auto-generated method stub          
    }
}

Answer 1

1. 您不需要将 while 循环与 Thread.sleeap() 结合使用。它正在破坏你的程序。
2. 您在这里想要实现的目标，即连续调用重绘，可以使用 javax.swing.Timer 轻松完成
3. 不要显式调用 paintComponent。对 real repaint() 方法的实际调用将为您完成此操作。无需创建模仿Repaint()
4. 使用 JPanel 进行绘画，而不是尝试在 JFrame 上绘画
5. 我会初始化，然后设置可见
6. 您的代码甚至无法编译，因此我可以尝试为您修复。
7. 使用 Java 命名约定:方法和变量以小写字母开头。
8. 这是一个example of a simple Login Window ，使用模态 JDialog
9. 了解如何使用Layout Managers而不是依赖 setBounds()

<小时/>

第 2 点。您的 main 应该如下所示

public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable(){
        public void run(){
            LoginWindow loginframe = new LoginWindow();
            loginframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            loginframe.initialize();
            loginframe.setVisible(true);
        }
    });
}

在构造函数中，使用 javax.swing.Timer 而不是 while 循环

private Timer timer = null;
private DrawPanel drawPanel = new DrawPanel();  // see below for DrawPanel
public LoginWindow() {
    // add drawPanel somewhere
    ...
    timer = new Timer (50, new ActionListener(){
        public void actionPerformed(ActionEvent e) {
            drawPanel.repaint();
        }
    });
    timer.start();
}

<小时/>

第 4 点。 有一个内部 JPanel 类，您可以在其中完成所有绘制，并将该组件添加到框架中。您需要重写 paintComponent 方法。

private DrawPanel extends JPanel {
    @Override
    protected void paintComponent(Graophics g) {
        super.paintComponent(g);
        Draw(g);
    }
}