flyweight.java

Conservator extends on the concept of a Flyweight Factory by allowing shared Flyweight objects to be

     package com.orbs.ref.pattern.conservator;

     import java.io.Serializable;

     /*********************************************************************
     * <P>
     * For a Flyweight to be used with a Conservator, it absolutely must
     * override its equals() method to return true if the values are the
     * same and it must be Cloneable.
     * <P>
     * The Flyweight, unlike the Heavyweight, implements the interface
     * to access the intrinsic state but not extrinsic state.
     * <P>
     * @author
     *   <A HREF="http://www.alumni.caltech.edu/~croft">David W. Croft</A>
     * @version
     *   1998-04-19
     *********************************************************************/

     public class  Flyweight implements Intrinsic, Cloneable, Serializable
     //////////////////////////////////////////////////////////////////////
     // Serializable just in case you want to save it.
     //////////////////////////////////////////////////////////////////////
     {

     private String  audioFileName;
     private String  imageFileName;

     //////////////////////////////////////////////////////////////////////
     // Constructor method
     //////////////////////////////////////////////////////////////////////

     public  Flyweight (
       String  audioFileName,
       String  imageFileName )
     //////////////////////////////////////////////////////////////////////
     {
       this.audioFileName = audioFileName;
       this.imageFileName = imageFileName;
     }

     //////////////////////////////////////////////////////////////////////
     // Accessor and mutator methods
     //////////////////////////////////////////////////////////////////////

     public String  getAudioFileName ( ) { return audioFileName; }
     public String  getImageFileName ( ) { return imageFileName; }

     public void  setAudioFileName ( String  audioFileName )
       { this.audioFileName = audioFileName; }

     public void  setImageFileName ( String  imageFileName )
       { this.imageFileName = imageFileName; }

     //////////////////////////////////////////////////////////////////////
     // Overridden methods
     //////////////////////////////////////////////////////////////////////

     /*********************************************************************
     * Creates a shallow clone.  Done by returning a new Flyweight with
     * the current instance variables passed as the arguments to the
     * constructor.
     *********************************************************************/
     public synchronized Object  clone ( )
     //////////////////////////////////////////////////////////////////////
     // Synchronized for your protection.
     //////////////////////////////////////////////////////////////////////
     {
       return new Flyweight ( audioFileName, imageFileName );
     }

     /*********************************************************************
     * Returns true if the argument is an instance of Flyweight
     * (including subclasses) and its instance values are equal.
     * <P>
     * If you subclass Flyweight, be sure to override this method by
     * calling the superclass method first and then comparing the
     * additional instance variables that are available in the subclass.
     *********************************************************************/
     public synchronized boolean  equals ( Object  other )
     //////////////////////////////////////////////////////////////////////
     // Synchronized for your protection.
     //////////////////////////////////////////////////////////////////////
     {
       if ( other == null ) return false;
       if ( other == this ) return true;
       if ( !( other instanceof Flyweight ) ) return false;
       Flyweight  that = ( Flyweight ) other;
       if ( ( this.audioFileName == null )
         && ( that.audioFileName != null ) ) return false;
       if ( ( this.imageFileName == null )
         && ( that.imageFileName != null ) ) return false;
       return this.audioFileName.equals ( that.audioFileName )
           && this.imageFileName.equals ( that.imageFileName );
     }

     //////////////////////////////////////////////////////////////////////
     //////////////////////////////////////////////////////////////////////
     }