/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.gui;import javax.swing.*;import java.awt.*;/** * A component subclass that demonstrates nested containers and components. * It creates the hierarchy shown below, and uses different colors to * distinguish the different nesting levels of the containers * * Containers---panel1----button1 *        |       |---panel2----button2 *        |       |        |----panel3----button3 *        |       |------panel4----button4 *        |                   |----button5 *        |---button6 */public class Containers extends JPanel {    public Containers() {	this.setBackground(Color.white);            // This component is white	this.setFont(new Font("Dialog", Font.BOLD, 24));	JPanel p1 = new JPanel();	p1.setBackground(new Color(200, 200, 200)); // Panel1 is darker	this.add(p1);                // p1 is contained by this component	p1.add(new JButton("#1"));   // Button 1 is contained in p1		JPanel p2 = new JPanel();	p2.setBackground(new Color(150, 150, 150)); // p2 is darker than p2	p1.add(p2);                  // p2 is contained in p1	p2.add(new JButton("#2"));   // Button 2 is contained in p2		JPanel p3 = new JPanel();	p3.setBackground(new Color(100, 100, 100)); // p3 is darker than p2	p2.add(p3);                  // p3 is contained in p2	p3.add(new JButton("#3"));   // Button 3 is contained in p3		JPanel p4 = new JPanel();	p4.setBackground(new Color(150, 150, 150)); // p4 is darker than p1	p1.add(p4);                  // p4 is contained in p1	p4.add(new JButton("#4"));   // Button4 is contained in p4	p4.add(new JButton("#5"));   // Button5 is also contained in p4		this.add(new JButton("#6")); // Button6 is contained in this component    }}