Demonstrates anonymous classes : Anonymous inner class « Class Definition « Java Tutorial






  1. Java Tutorial
  2. Class Definition
  3. Anonymous inner class
/*
 *     file: InnerClassDemo.java
 *  package: oreilly.hcj.nested
 *
 * This software is granted under the terms of the Common Public License,
 * CPL, which may be found at the following URL:
 * http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
 *
 * Copyright(c) 2003-2005 by the authors indicated in the @author tags.
 * All Rights are Reserved by the various authors.
 *
 ########## DO NOT EDIT ABOVE THIS LINE ########## */

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;

/**
 * Demonstrates anonymous classes.
 * 
 * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
 * @version $Revision: 1.3 $
 */
public class InnerClassDemo extends JDialog {
  /** Holds the logo image */
  private static final ImageIcon LOGO;

  /** Holds the location of the logo image. */
  private static final String LOGO_LOCATION = "sojm/nested/oreilly_header3.gif";

  static {
    LOGO = new ImageIcon(ClassLoader.getSystemClassLoader().getResource(LOGO_LOCATION));
  }

  /** Holds a reference to the content pane. */
  private final Container contentPane;

  /** holds a demo variable. */
  private int beepCount = 1;

  /**
   * Creates a new AnonymousDemo object.
   * 
   * @param beepCount
   *          THe number of times to beep when the button is pressed.
   */
  public InnerClassDemo(final int beepCount) {
    super();
    setTitle("Anonymous Demo");
    contentPane = getContentPane();
    contentPane.setLayout(new BorderLayout());

    JLabel logoLabel = new JLabel(LOGO);
    contentPane.add(BorderLayout.NORTH, logoLabel);

    JButton btn = new BeepButton("Beep");
    contentPane.add(BorderLayout.SOUTH, btn);
    pack();
    this.beepCount = beepCount;
  }

  /**
   * Setter for the property demo.
   * 
   * @param beepCount
   *          The new value for demo.
   */
  public void setBeepCount(final int beepCount) {
    this.beepCount = beepCount;
  }

  /**
   * Getter for the property demo.
   * 
   * @return The current value of demo.
   */
  public int getBeepCount() {
    return beepCount;
  }

  /**
   * Run the demo
   * 
   * @param args
   *          Command Line Arguments.
   */
  public static final void main(final String[] args) {
    InnerClassDemo demo = new InnerClassDemo(4);
    demo.show();
    System.out.println("Done");
  }

  /**
   * An inner class to implement an action listener.
   * 
   * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
   * @version $Revision: 1.3 $
   */
  private class BeepButton extends JButton implements ActionListener {
    /**
     * Creates a new BeepButton object.
     * 
     * @param text
     *          The text to use for the beep button.
     */
    public BeepButton(final String text) {
      super(text);
      addActionListener(this);
    }

    /**
     * @see java.awt.event.ActionListener
     */
    public void actionPerformed(final ActionEvent event) {
      try {
        for (int count = 0; count < beepCount; count++) {
          Toolkit.getDefaultToolkit().beep();
          Thread.sleep(100); // wait for the old beep to finish.
        }
      } catch (final InterruptedException ex) {
        throw new RuntimeException(ex);
      }
    }
  }
}

/* ########## End of File ########## */








5.15.Anonymous inner class
5.15.1.Demonstrate an inner class.
5.15.2.Define an inner class within a for loop.
5.15.3.Use anonymous inner classes
5.15.4.Building the anonymous inner class in-place
5.15.5.Anonymous inner class cannot have a named constructor, only an instance initializer
5.15.6.Creating a constructor for an anonymous inner class
5.15.7.Using 'instance initialization' to perform construction on an anonymous inner class
5.15.8.Argument must be final to use inside anonymous inner class
5.15.9.A method that returns an anonymous inner class
5.15.10.An anonymous inner class that calls the base-class constructor
5.15.11.An anonymous inner class that performs initialization
5.15.12.Demonstrates method-scoped inner classes
5.15.13.Demonstrates anonymous classes
5.15.14.Demonstration of some static nested classes
5.15.15.Access inner class from outside
5.15.16.Accessing its enclosing instance from an inner class