如何与其他的JPanel

Question

取代的JPanel我想与另一位在一个JFrame 我已经搜索并尝试我的代码，但没有什么是发生 更换一个JPanel这是我的代码：

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); 
    } 
} 

有人可以帮助我？非常感谢

Answer 1

在完成删除和添加操作后，您必须在包含面板上调用validate()然后repaint()。

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

Answer 2

1. 不要使用AbsoluteLayout

2. 变化validate();在actionPerformed到contain.validate();与contain.repaint();

3. 重命名类名（Java的保留字，或方法名称）如下Frame（ java.awt.Frame）至MyFrame（例如）

4. 使用CardLayout改为移除，然后在运行时

Answer 3

你需要做这样的添加新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

的几个问题与您的代码。这里是固定的版本：

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); 
    } 
}