如何與其他的JPanel

Question

取代的JPanel我想與另一位在一個JFrame 我已經搜索並嘗試我的代碼，但沒有什麼是發生 更換一個JPanel這是我的代碼：

public class Frame extends JFrame { 

    private Container contain; 
    private JPanel reChange,reChange2; 
    private JButton reChangeButton; 

    public Frame() { 
     super("Change a panel"); 
     setSize(350, 350); 
     setLayout(null); 
     setLocationRelativeTo(null); 
     setResizable(false); 

     reChange = new JPanel(null); 
     reChange.setBackground(Color.red); 
     reChange.setSize(240, 225); 
     reChange.setBounds(50, 50, 240, 225); 
     add(reChange); 

     reChangeButton = new JButton("Change It"); 
     reChangeButton.setBounds(20, 20, 100, 20); 
     add(reChangeButton); 

     reChangeButton.addActionListener(new ActionListener() { 
      @Override 
      public void actionPerformed(ActionEvent e) { 
       //System.out.println("in"); 
       contain = getContentPane(); 
       contain.removeAll(); 
       //System.out.println("in2"); 

       reChange2 = new JPanel(null); 
       reChange2.setBackground(Color.white); 
       reChange2.setSize(240, 225); 
       reChange2.setBounds(50, 50, 240, 225); 
       //System.out.println("in3"); 

       contain.add(reChange2); 
       validate(); 
       //System.out.println("in4"); 
       setVisible(true); 
       //System.out.println("in5"); 
      } 
     }); 

    } 

    public static void main(String[] args) { 
     Frame frame = new Frame(); 
     frame.setVisible(true); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    } 
} 

有人可以幫助我？非常感謝

Answer 1

在完成刪除和添加操作後，您必須在包含面板上調用validate()然後repaint()。

contain.validate(); 
contain.repaint(); 

Answer 2

1. 不要使用AbsoluteLayout

2. 變化validate();在actionPerformed到contain.validate();與contain.repaint();

3. 重命名類名（Java的保留字，或方法名稱）如下Frame（ java.awt.Frame）至MyFrame（例如）

4. 使用CardLayout改爲移除，然後在運行時

Answer 3

你需要做這樣的添加新JPanel：

 public void actionPerformed(ActionEvent e) { 
     //System.out.println("in"); 
     contain = getContentPane(); 
     contain.removeAll(); 
     //System.out.println("in2"); 

     reChange2 = new JPanel(null); 
     reChange2.setBackground(Color.white); 
     reChange2.setSize(240, 225); 
     reChange2.setBounds(50, 50, 240, 225); 
     //System.out.println("in3"); 

     contain.add(reChange2); 
     validate(); 
     repaint(); 
     //System.out.println("in4"); 
     setVisible(true); 
     //System.out.println("in5"); 
    } 
}); 

Answer 4

的幾個問題與您的代碼。這裏是固定的版本：

public class Frame extends JFrame { 

    private Container contain; 
    private JPanel reChange,reChange2; 
    private JButton reChangeButton; 

    public Frame() { 
     super("Change a panel"); 
     setSize(350, 350); 
     getContentPane().setLayout(null); // Changed here 
     setLocationRelativeTo(null); 
     setResizable(false); 

     reChange = new JPanel(null); 
     reChange.setBackground(Color.red); 
     reChange.setSize(240, 225); 
     reChange.setBounds(50, 50, 240, 225); 
     getContentPane().add(reChange); // Changed here 

     reChangeButton = new JButton("Change It"); 
     reChangeButton.setBounds(20, 20, 100, 20); 
     getContentPane().add(reChangeButton); // Changed here 

     reChangeButton.addActionListener(new ActionListener() { 
      @Override 
      public void actionPerformed(ActionEvent e) { 
       contain = getContentPane(); 
       contain.removeAll(); 

       reChange2 = new JPanel(null); 
       reChange2.setBackground(Color.white); 
       reChange2.setSize(240, 225); 
       reChange2.setBounds(50, 50, 240, 225); 

       contain.add(reChange2); 
       invalidate(); // Changed here 
       repaint(); // Changed here 
      } 
     }); 
    } 

    public static void main(String[] args) { 
     Frame frame = new Frame(); 
     frame.setVisible(true); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    } 
}