如何添加一个扩展JPanel的类，并显示其自己的面板和按钮？

Question

I put a JPanel(jp1) on the JFrame(fr1) , but where is jp2 going?

I would like to display the jp2 contains in jp1 on fr1 ?

(the button "start!" and "DEBUGGING" should both displayed on the window)

How to do?

import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;

public class F extends JFrame {

/**
 * @param args
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub
    F fr1 = new F();
    P jp1 = new P();
    jp1.add(new JButton("start!"));
    fr1.setSize(1024, 768);
    fr1.add(jp1, BorderLayout.CENTER);
    fr1.setVisible(true);

    }

}

class P extends JPanel{
    private JPanel jp2;
    private JButton b2;
    public P(){
        jp2 = new JPanel();
        jp2.setBackground(Color.green);
        b2 = new JButton("DEBUGGING.");
        jp2.add(b2);
    }
}

Answer 1

use this.add or just add inside your class p to add component to jpanel p[class p].your class p is itself a jpanel because it is extended by jpanel .so you need to add jp2 to that panel .

and care about your layout of panel[class p] you can set layout by setLayout.... inside class p

class P extends JPanel{
    private JPanel jp2;
    private JButton b2;
    public P(){
        jp2 = new JPanel();
        jp2.setBackground(Color.green);
        b2 = new JButton("DEBUGGING.");
        jp2.add(b2);
        // setLayout.....use a appropriate layout if you need
        add(jp2);
    }
}

Answer 2

You never add jp2 in P to anything

class P extends JPanel{
    private JPanel jp2;
    private JButton b2;
    public P(){
        jp2 = new JPanel();
        jp2.setBackground(Color.green);
        b2 = new JButton("DEBUGGING.");
        jp2.add(b2);
        //???
    }
}

Add add(jp2); as the last statement