java嵌套在彼此之上的面板打印

Question

import java.awt.*;
import javax.swing.*;

public class Panels extends JApplet
{
  private Container c = getContentPane();

  public void init()
  {
    BorderLayout bl = new BorderLayout();   
    setLayout(bl);

    add(new JButton("East "),   BorderLayout.EAST);  
    add(new JButton("West "),   BorderLayout.WEST);  
    add(new JButton("North "),  BorderLayout.NORTH); 
    add(new JButton("South "),  BorderLayout.SOUTH);

    addCenterPanel();
  }

  void addCenterPanel()
  {
    JPanel p = new JPanel();
    setLayout(new BorderLayout());

    add(new JButton("Right "),  BorderLayout.EAST);  
    add(new JButton("Left "),   BorderLayout.WEST);  
    add(new JButton("Up "),     BorderLayout.NORTH); 
    add(new JButton("Down "),   BorderLayout.SOUTH);

    addInnermostPanel();
  }

  void addInnermostPanel()
  {
    JPanel center = new JPanel();

    center.setLayout(new BorderLayout());

    add(new JButton("> "),  BorderLayout.EAST);  
    add(new JButton("< "),  BorderLayout.WEST);  
    add(new JButton("^ "),  BorderLayout.NORTH); 
    add(new JButton("v "),  BorderLayout.SOUTH);
    add(new JButton("O"),   BorderLayout.CENTER);  
  }
}

I want the panels to display inside of each other (in the CENTER region) , but they are printing on top of each other and for whatever reason I cant figure out what Im missing. Thanks in advance, any help is appreciated

Answer 1

Here is you're code should be like this;

import java.awt.*;
import javax.swing.*;

public class Panels extends JFrame
{
  private Container c = getContentPane();

  public void init()
  {
    BorderLayout bl = new BorderLayout();
    setLayout(bl);
    setDefaultCloseOperation(3);
    setLocationRelativeTo(null);

    add(new JButton("East "),   BorderLayout.EAST);
    add(new JButton("West "),   BorderLayout.WEST);
    add(new JButton("North "),  BorderLayout.NORTH);
    add(new JButton("South "),  BorderLayout.SOUTH);

    add(addCenterPanel(),"Center");
  }

  JPanel addCenterPanel()
  {
    JPanel p = new JPanel();
    p.setLayout(new BorderLayout());

    p.add(new JButton("Right "),  BorderLayout.EAST);
    p.add(new JButton("Left "),   BorderLayout.WEST);
    p.add(new JButton("Up "),     BorderLayout.NORTH);
    p.add(new JButton("Down "),   BorderLayout.SOUTH);

    p.add(addInnermostPanel(),"Center");
    return p;
  }

  JPanel addInnermostPanel()
  {
    JPanel center = new JPanel();

    center.setLayout(new BorderLayout());

    center.add(new JButton("> "),  BorderLayout.EAST);
    center.add(new JButton("< "),  BorderLayout.WEST);
    center.add(new JButton("^ "),  BorderLayout.NORTH);
    center.add(new JButton("v "),  BorderLayout.SOUTH);
    center.add(new JButton("O"),   BorderLayout.CENTER);
    return center;
  }

  public static void main(String ...args){
       new Panels().setVisible(true);
  }
  public Panels(){
      init();
      pack();

  }
}

Note : I used JFrame instead applet. Also I just posted the code because it takes many time to describe the whole program, I think only the code will be enough.

If you have a question, write it in the comment.

Answer 2

In addCenterPanel youre adding all components directly to the applet itself rather than to the JPanel p . That panel is not being added to the applet itself. In addInnermostPanel the components are again added to the applet and the center JPanel is never added to the container