Java/Swing JFC/Basics

CelsiusConverter: the use of JButton, JTextField and JLabel

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
// v 1.3
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
// This example demonstrates the use of JButton, JTextField and JLabel.
public class CelsiusConverter implements ActionListener {
  JFrame converterFrame;
  JPanel converterPanel;
  JTextField tempCelsius;
  JLabel celsiusLabel, fahrenheitLabel;
  JButton convertTemp;
  // Constructor
  public CelsiusConverter() {
    // Create the frame and container.
    converterFrame = new JFrame("Convert Celsius to Fahrenheit");
    converterPanel = new JPanel();
    converterPanel.setLayout(new GridLayout(2, 2));
    // Add the widgets.
    addWidgets();
    // Add the panel to the frame.
    converterFrame.getContentPane()
        .add(converterPanel, BorderLayout.CENTER);
    // Exit when the window is closed.
    converterFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Show the converter.
    converterFrame.pack();
    converterFrame.setVisible(true);
  }
  // Create and add the widgets for converter.
  private void addWidgets() {
    // Create widgets.
    tempCelsius = new JTextField(2);
    celsiusLabel = new JLabel("Celsius", SwingConstants.LEFT);
    convertTemp = new JButton("Convert...");
    fahrenheitLabel = new JLabel("Fahrenheit", SwingConstants.LEFT);
    // Listen to events from Convert button.
    convertTemp.addActionListener(this);
    // Add widgets to container.
    converterPanel.add(tempCelsius);
    converterPanel.add(celsiusLabel);
    converterPanel.add(convertTemp);
    converterPanel.add(fahrenheitLabel);
    celsiusLabel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    fahrenheitLabel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
  }
  // Implementation of ActionListener interface.
  public void actionPerformed(ActionEvent event) {
    // Parse degrees Celsius as a double and convert to Fahrenheit.
    int tempFahr = (int) ((Double.parseDouble(tempCelsius.getText())) * 1.8 + 32);
    fahrenheitLabel.setText(tempFahr + " Fahrenheit");
  }
  // main method
  public static void main(String[] args) {
    // Set the look and feel.
    try {
      UIManager.setLookAndFeel(UIManager
          .getCrossPlatformLookAndFeelClassName());
    } catch (Exception e) {
    }
    CelsiusConverter converter = new CelsiusConverter();
  }
}

Creates two JPanels (opaque), one containing another opaque JPanel, and the other containing a non-opaque JPanel

import java.awt.Color;
import java.awt.FlowLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class OpaqueExample extends JFrame {
  public OpaqueExample() {
    super("Opaque JPanel Demo");
    setSize(400, 200);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    JPanel opaque = createNested(true);
    JPanel notOpaque = createNested(false);
    // Throw it all together
    getContentPane().setLayout(new FlowLayout());
    getContentPane().add(opaque);
    getContentPane().add(notOpaque);
  }
  public static void main(String[] args) {
    OpaqueExample oe = new OpaqueExample();
    oe.setVisible(true);
  }
  public JPanel createNested(boolean opaque) {
    JPanel outer = new JPanel(new FlowLayout());
    JPanel inner = new JPanel(new FlowLayout());
    outer.setBackground(Color.white);
    inner.setBackground(Color.black);
    inner.setOpaque(opaque);
    inner.setBorder(BorderFactory.createLineBorder(Color.gray));
    inner.add(new JButton("Button"));
    outer.add(inner);
    return outer;
  }
}

GUI invoked from the event-dispatching thread

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenuBar;
/* TopLevelDemo.java requires no other files. */
public class TopLevelDemo {
  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    //Make sure we have nice window decorations.
    JFrame.setDefaultLookAndFeelDecorated(true);
    //Create and set up the window.
    JFrame frame = new JFrame("TopLevelDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    //Create the menu bar. Make it have a cyan background.
    JMenuBar cyanMenuBar = new JMenuBar();
    cyanMenuBar.setOpaque(true);
    cyanMenuBar.setBackground(Color.cyan);
    cyanMenuBar.setPreferredSize(new Dimension(200, 20));
    //Create a yellow label to put in the content pane.
    JLabel yellowLabel = new JLabel();
    yellowLabel.setOpaque(true);
    yellowLabel.setBackground(Color.yellow);
    yellowLabel.setPreferredSize(new Dimension(200, 180));
    //Set the menu bar and add the label to the content pane.
    frame.setJMenuBar(cyanMenuBar);
    frame.getContentPane().add(yellowLabel, BorderLayout.CENTER);
    //Display the window.
    frame.pack();
    frame.setVisible(true);
  }
  public static void main(String[] args) {
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application"s GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}

Hello World Swing

import javax.swing.JFrame;
import javax.swing.JLabel;
public class HelloWorldSwing {
  public static void main(String[] args) {
    JFrame frame = new JFrame("HelloWorldSwing");
    final JLabel label = new JLabel("Hello World");
    frame.getContentPane().add(label);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
}

LunarPhases: the use of JButton, JTextField and JLabel

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
// v 1.3
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.URL;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
// This example demonstrates the use of JButton, JTextField
// and JLabel.
public class LunarPhases implements ActionListener {
  final static int NUM_IMAGES = 8;
  final static int START_INDEX = 3;
  ImageIcon[] images = new ImageIcon[NUM_IMAGES];
  JPanel mainPanel, selectPanel, displayPanel;
  JComboBox phaseChoices = null;
  JLabel phaseIconLabel = null;
  // Constructor
  public LunarPhases() {
    // Create the phase selection and display panels.
    selectPanel = new JPanel();
    displayPanel = new JPanel();
    // Add various widgets to the sub panels.
    addWidgets();
    // Create the main panel to contain the two sub panels.
    mainPanel = new JPanel();
    mainPanel.setLayout(new GridLayout(2, 1, 5, 5));
    mainPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    // Add the select and display panels to the main panel.
    mainPanel.add(selectPanel);
    mainPanel.add(displayPanel);
  }
  // Create and the widgets to select and display the phases of the moon.
  private void addWidgets() {
    // Get the images and put them into an array of ImageIcon.
    for (int i = 0; i < NUM_IMAGES; i++) {
      String imageName = "images/image" + i + ".jpg";
      System.out.println("getting image: " + imageName);
//      URL iconURL = ClassLoader.getSystemResource(imageName);
  //    ImageIcon icon = new ImageIcon(iconURL);
      images[i] = icon;
    }
    // Create label for displaying moon phase images and put a border around
    // it.
    phaseIconLabel = new JLabel();
    phaseIconLabel.setHorizontalAlignment(JLabel.CENTER);
    phaseIconLabel.setVerticalAlignment(JLabel.CENTER);
    phaseIconLabel.setVerticalTextPosition(JLabel.CENTER);
    phaseIconLabel.setHorizontalTextPosition(JLabel.CENTER);
    phaseIconLabel.setBorder(BorderFactory.createCompoundBorder(
        BorderFactory.createLoweredBevelBorder(), BorderFactory
            .createEmptyBorder(5, 5, 5, 5)));
    phaseIconLabel.setBorder(BorderFactory.createCompoundBorder(
        BorderFactory.createEmptyBorder(0, 0, 10, 0), phaseIconLabel
            .getBorder()));
    // Create combo box with lunar phase choices.
    String[] phases = { "New", "Waxing Crescent", "First Quarter",
        "Waxing Gibbous", "Full", "Waning Gibbous", "Third Quarter",
        "Waning Crescent" };
    phaseChoices = new JComboBox(phases);
    phaseChoices.setSelectedIndex(START_INDEX);
    // Display the first image.
    phaseIconLabel.setIcon(images[START_INDEX]);
    phaseIconLabel.setText("");
    // Add border around the select panel.
    selectPanel.setBorder(BorderFactory.createCompoundBorder(BorderFactory
        .createTitledBorder("Select Phase"), BorderFactory
        .createEmptyBorder(5, 5, 5, 5)));
    // Add border around the display panel.
    displayPanel.setBorder(BorderFactory.createCompoundBorder(BorderFactory
        .createTitledBorder("Display Phase"), BorderFactory
        .createEmptyBorder(5, 5, 5, 5)));
    // Add moon phases combo box to select panel and image label to
    // displayPanel.
    selectPanel.add(phaseChoices);
    displayPanel.add(phaseIconLabel);
    // Listen to events from combo box.
    phaseChoices.addActionListener(this);
  }
  // Implementation of ActionListener interface.
  public void actionPerformed(ActionEvent event) {
    if ("comboBoxChanged".equals(event.getActionCommand())) {
      // update the icon to display the new phase
      phaseIconLabel.setIcon(images[phaseChoices.getSelectedIndex()]);
    }
  }
  // main method
  public static void main(String[] args) {
    // create a new instance of LunarPhases
    LunarPhases phases = new LunarPhases();
    // Create a frame and container for the panels.
    JFrame lunarPhasesFrame = new JFrame("Lunar Phases");
    // Set the look and feel.
    try {
      UIManager.setLookAndFeel(UIManager
          .getCrossPlatformLookAndFeelClassName());
    } catch (Exception e) {
    }
    lunarPhasesFrame.setContentPane(phases.mainPanel);
    // Exit when the window is closed.
    lunarPhasesFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Show the converter.
    lunarPhasesFrame.pack();
    lunarPhasesFrame.setVisible(true);
  }
}

Separating GUI logic and business objects

// : c14:Separation.java
// Separating GUI logic and business objects.
// <applet code=Separation width=250 height=150></applet>
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
class BusinessLogic {
  private int modifier;
  public BusinessLogic(int mod) {
    modifier = mod;
  }
  public void setModifier(int mod) {
    modifier = mod;
  }
  public int getModifier() {
    return modifier;
  }
  // Some business operations:
  public int calculation1(int arg) {
    return arg * modifier;
  }
  public int calculation2(int arg) {
    return arg + modifier;
  }
}
public class Separation extends JApplet {
  private JTextField t = new JTextField(15), mod = new JTextField(15);
  private JButton calc1 = new JButton("Calculation 1"), calc2 = new JButton(
      "Calculation 2");
  private BusinessLogic bl = new BusinessLogic(2);
  public static int getValue(JTextField tf) {
    try {
      return Integer.parseInt(tf.getText());
    } catch (NumberFormatException e) {
      return 0;
    }
  }
  class Calc1L implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      t.setText(Integer.toString(bl.calculation1(getValue(t))));
    }
  }
  class Calc2L implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      t.setText(Integer.toString(bl.calculation2(getValue(t))));
    }
  }
  // If you want something to happen whenever
  // a JTextField changes, add this listener:
  class ModL implements DocumentListener {
    public void changedUpdate(DocumentEvent e) {
    }
    public void insertUpdate(DocumentEvent e) {
      bl.setModifier(getValue(mod));
    }
    public void removeUpdate(DocumentEvent e) {
      bl.setModifier(getValue(mod));
    }
  }
  public void init() {
    Container cp = getContentPane();
    cp.setLayout(new FlowLayout());
    cp.add(t);
    calc1.addActionListener(new Calc1L());
    calc2.addActionListener(new Calc2L());
    JPanel p1 = new JPanel();
    p1.add(calc1);
    p1.add(calc2);
    cp.add(p1);
    mod.getDocument().addDocumentListener(new ModL());
    JPanel p2 = new JPanel();
    p2.add(new JLabel("Modifier:"));
    p2.add(mod);
    cp.add(p2);
  }
  public static void main(String[] args) {
    run(new Separation(), 250, 100);
  }
  public static void run(JApplet applet, int width, int height) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(applet);
    frame.setSize(width, height);
    applet.init();
    applet.start();
    frame.setVisible(true);
  }
} ///:~

Standalone GUI program that shows paint, repaint, and update

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
///
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JLabel;
/** Standalone GUI program that shows paint, repaint, and update */
public class PaintMethods extends JLabel {
  /** "main program" method - construct and show */
  public static void main(String[] av) {
    final JFrame f = new JFrame("PaintMethods demo");
    f.getContentPane().add("Center", new PaintMethods("Testing 1 2 3"));
    f.pack();
    f.setVisible(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
  public PaintMethods(String s) {
    super(s);
  }
  public void paint(Graphics g) {
    System.out.println("Paint");
    super.paint(g);
  }
  public void repaint() {
    System.out.println("repaint");
    super.repaint();
  }
  public void update(Graphics g) {
    System.out.println("update");
    super.update(g);
  }
}

Swing Application

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
// v 1.3
import java.awt.BorderLayout;
import java.awt.ruponent;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
public class SwingApplication {
  private static String labelPrefix = "Number of button clicks: ";
  private int numClicks = 0;
  public Component createComponents() {
    final JLabel label = new JLabel(labelPrefix + "0    ");
    JButton button = new JButton("I"m a Swing button!");
    button.setMnemonic(KeyEvent.VK_I);
    button.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        numClicks++;
        label.setText(labelPrefix + numClicks);
      }
    });
    label.setLabelFor(button);
    /*
     * An easy way to put space between a top-level container and its
     * contents is to put the contents in a JPanel that has an "empty"
     * border.
     */
    JPanel pane = new JPanel();
    pane.setBorder(BorderFactory.createEmptyBorder(30, //top
        30, //left
        10, //bottom
        30) //right
        );
    pane.setLayout(new GridLayout(0, 1));
    pane.add(button);
    pane.add(label);
    return pane;
  }
  public static void main(String[] args) {
    try {
      UIManager.setLookAndFeel(UIManager
          .getCrossPlatformLookAndFeelClassName());
    } catch (Exception e) {
    }
    //Create the top-level container and add contents to it.
    JFrame frame = new JFrame("SwingApplication");
    SwingApplication app = new SwingApplication();
    Component contents = app.createComponents();
    frame.getContentPane().add(contents, BorderLayout.CENTER);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
}

The revalidate method to dynamically update the

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class RevalidateExample extends JFrame {
  public RevalidateExample() {
    super("Revalidation Demo");
    setSize(300, 150);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Font font = new Font("Dialog", Font.PLAIN, 10);
    final JButton b = new JButton("Add");
    b.setFont(font);
    Container c = getContentPane();
    c.setLayout(new FlowLayout());
    c.add(b);
    b.addActionListener(new ActionListener() {
      // Increase the size of the button"s font each time it"s clicked
      int size = 20;
      public void actionPerformed(ActionEvent ev) {
        b.setFont(new Font("Dialog", Font.PLAIN, ++size));
        b.revalidate(); // invalidates the button & validates its root pane
      }
    });
  }
  public static void main(String[] args) {
    RevalidateExample re = new RevalidateExample();
    re.setVisible(true);
  }
}

This example demonstrates the use of JButton, JTextField and JLabel

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
// v 1.3
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
// This example demonstrates the use of JButton, JTextField and JLabel.
public class CelsiusConverter2 implements ActionListener {
  JFrame converterFrame;
  JPanel converterPanel;
  JTextField tempCelsius;
  JLabel celsiusLabel, fahrenheitLabel;
  JButton convertTemp;
  // Constructor
  public CelsiusConverter2() {
    // Create the frame and container.
    converterFrame = new JFrame("Convert Celsius to Fahrenheit");
    converterPanel = new JPanel();
    converterPanel.setLayout(new GridLayout(2, 2));
    // Add the widgets.
    addWidgets();
    // Add the panel to the frame.
    converterFrame.getContentPane()
        .add(converterPanel, BorderLayout.CENTER);
    // Exit when the window is closed.
    converterFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Show the converter.
    converterFrame.pack();
    converterFrame.setVisible(true);
  }
  // Create and add the widgets for converter.
  private void addWidgets() {
    // Create widgets.
    ImageIcon icon = new ImageIcon("images/convert.gif",
        "Convert temperature");
    tempCelsius = new JTextField(2);
    celsiusLabel = new JLabel("Celsius", SwingConstants.LEFT);
    convertTemp = new JButton(icon);
    fahrenheitLabel = new JLabel("Fahrenheit", SwingConstants.LEFT);
    celsiusLabel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    fahrenheitLabel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    // Listen to events from Convert button.
    convertTemp.addActionListener(this);
    // Add widgets to container.
    converterPanel.add(tempCelsius);
    converterPanel.add(celsiusLabel);
    converterPanel.add(convertTemp);
    converterPanel.add(fahrenheitLabel);
  }
  // Implementation of ActionListener interface.
  public void actionPerformed(ActionEvent event) {
    // Parse degrees Celsius as a double and convert to Fahrenheit.
    int tempFahr = (int) ((Double.parseDouble(tempCelsius.getText())) * 1.8 + 32);
    // Set fahrenheitLabel to new value and set font color based on the
    // temperature.
    if (tempFahr <= 32) {
      fahrenheitLabel
          .setText("<html><Font Color=blue>"
              + tempFahr
              + "&#176 </Font><Font Color=black> Fahrenheit</font></html>");
    } else if (tempFahr <= 80) {
      fahrenheitLabel
          .setText("<html><Font Color=green>"
              + tempFahr
              + "&#176 </Font><Font Color=black> Fahrenheit </Font></html>");
    } else {
      fahrenheitLabel
          .setText("<html><Font Color=red>"
              + tempFahr
              + "&#176 </Font><Font Color=black> Fahrenheit</Font></html>");
    }
  }
  // main method
  public static void main(String[] args) {
    // set the look and feel
    try {
      UIManager.setLookAndFeel(UIManager
          .getCrossPlatformLookAndFeelClassName());
    } catch (Exception e) {
    }
    CelsiusConverter2 converter = new CelsiusConverter2();
  }
}