Cache Managment

The class that will be cached.
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class MyObject{

    private MyObjectKey myObjectKey;
    
    public MyObject(MyObjectKey key){
        myObjectKey = key;
    }
     
    public MyObjectKey getKey(){
        return myObjectKey;
    }   
}
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The key class for the MyObject class.
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class MyObjectKey{
    
    String key;
    
    public MyObjectKey(String key){
        this.key = key;
    }

    public int hashCode(){ return key.hashCode();}

    public boolean equals(Object obj){
        return (obj instanceof MyObjectKey && key.equals(((MyObjectKey)(obj)).key));
    }
}
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The class that creates (intstantiates) the MyObject
classes for a client but does not use any caching.
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class MyObjectCreator{

    public MyObject createMyObject(MyObjectKey key){
        System.out.println("creating new object");
        /* imagine the MyObject class is build up 
           from data base calls and is quite large.
        */
        return new MyObject(key);
    }

}

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The CacheManager class. 
This is the class that will be utilized by a client.
This class caches MyObjects only creating them if
a MyObject does not exist with the given key. 
Notice CacheManager is a MyObjectCreator so a client 
need not be aware that a cache manager is being
utilized.
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class CacheManager extends MyObjectCreator{

    private Cache cache = new Cache();
    
    public MyObject createMyObject(MyObjectKey key){
        System.out.println("checking cache");
        MyObject temp = cache.getObject(key);
        if(temp == null){
            temp = super.createMyObject(key);
            cache.setObject(temp);
        }
        return temp;
    }
}
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The actual Cache class utilized by CacheManager.
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class Cache{
   
    private Hashtable cache = new Hashtable();

    public MyObject getObject(MyObjectKey key){
        return (MyObject)cache.get(key);
    }

    public void setObject(MyObject myObject){
        cache.put(myObject.getKey(),myObject);
    }
}
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The client class, a test stub to run it all.
Remember the CacheManager is a MyObjectCreator. 
As a result if there were MyObjectCreator  accessors 
(getters and setters) in this class (it was a true client 
instead of a test stub) it would be unaware of any change 
when utilizing the cache system. 
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class Test{

    public static void main(String[] args){
        System.out.println("class: Test, method: main");

        MyObjectCreator myObjectCreator = new CacheManager();
        
        myObjectCreator.createMyObject(new MyObjectKey("one"));
        myObjectCreator.createMyObject(new MyObjectKey("two"));
        myObjectCreator.createMyObject(new MyObjectKey("three"));
        
        myObjectCreator.createMyObject(new MyObjectKey("one"));
        myObjectCreator.createMyObject(new MyObjectKey("two"));
        myObjectCreator.createMyObject(new MyObjectKey("three"));
    }
}
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Here is a tar with the above java classes in it. 
cacheManagment.tar