重繪時JButton被複制？

Question

我有一個JFrame其中有2 JPanel其中：a PaintPanel（與paint()方法）和ButtonPanel（帶按鈕）。當我調用PaintPanel的repaint()（但單擊按鈕）ButtonPanel的按鈕正在繪製在PaintPanel！它不是可點擊或任何東西，它只是在那裏。

我試圖重新使用這段代碼的問題：

public class Main { 

    public static void main(String[] args) { 
     JFrame frame = new JFrame("frame"); 
     frame.setSize(400,400); 
     frame.setLayout(new GridLayout(2,1)); 
     PaintPanel paint = new PaintPanel(); 
     ButtonPanel buttons = new ButtonPanel(paint); 
     frame.add(paint); 
     frame.add(buttons); 
     frame.setVisible(true); 
    } 
} 

public class PaintPanel extends JPanel{ 
    public void paint(Graphics g){ 
     g.drawRect(10, 10, 10, 10); 
    } 
} 

public class ButtonPanel extends JPanel implements ActionListener{ 

    private PaintPanel paintPanel; 

    public ButtonPanel(PaintPanel paintPanel){ 
     this.paintPanel=paintPanel; 
     JButton button = new JButton("button"); 
     button.addActionListener(this); 
     add(button); 
    } 

    @Override 
    public void actionPerformed(ActionEvent arg0) { 
     paintPanel.repaint();   
    } 
} 

這重新前人的精力我有問題（對不起，奇碼標記，似乎無法得到它的權利）。

我真的希望你一個人知道這裏發生了什麼，因爲我不...

Answer 1

首先，你應該重寫paintComponent()而不是paint()。這是Swing最佳實踐的一部分，當涉及到一些面板定製。

其次，這裏是爲我的作品（我不知道爲什麼你沒有，但：S）：代碼

public class Main { 

    public static void main(String[] args) { 

     JFrame frame = new JFrame("frame"); 
     frame.setSize(400, 400); 
     // frame.setLayout(new GridLayout(2, 1)); 
     PaintPanel paint = new PaintPanel(); 
     ButtonPanel buttons = new ButtonPanel(paint); 
     // frame.add(paint); 
     // frame.add(buttons); 
     frame.setVisible(true); 

     JPanel pan = new JPanel(new BorderLayout()); 
     pan.add(paint); 
     pan.add(buttons, BorderLayout.SOUTH); 
     frame.add(pan); 

    } 
} 

class PaintPanel extends JPanel { 

    @Override 
    protected void paintComponent(Graphics g) { 
     super.paintComponent(g); 
     g.setColor(new Color(new Random().nextInt())); 
     g.drawRect(10, 10, 10, 10); 
    } 
} 

class ButtonPanel extends JPanel implements ActionListener { 

    private final PaintPanel paintPanel; 

    public ButtonPanel(PaintPanel paintPanel) { 

     this.paintPanel = paintPanel; 
     JButton button = new JButton("button"); 
     button.addActionListener(this); 
     add(button); 
    } 

    @Override 
    public void actionPerformed(ActionEvent arg0) { 
     if (getParent() != null) { 
      getParent().repaint(); 
     } 
    } 
}