uk.ac.starlink.util
Class ObjectFactory

java.lang.Object
  extended byuk.ac.starlink.util.ObjectFactory

public class ObjectFactory
extends Object

Manages dynamic creation of objects from a known set of classes. An ObjectFactory keeps a list of classes with associated nicknames; the idea is that you can obtain an instance of a given class by supplying the nickname in question. Instead of a nickname you can use the fully qualified classname, whether or not it has previously been registered. Any class registered must be a subclass of the superclass specified when this factory is constructed, and must have a no-arg constructor.

Since:
10 Aug 2005

Constructor Summary
ObjectFactory(Class clazz)
          Constructor.
 
Method Summary
 Object createObject(String name)
          Constructs and returns an object from one of the classes registered with this factory.
 Class getFactoryClass()
          Returns the class of which any object created by this factory is guaranteed to be an instance.
 String[] getNickNames()
          Returns a list of the nicknames which have been registered.
 boolean isRegistered(String name)
          Indicates whether this factory knows about a given name.
 void register(String nickName, String className)
          Registers a class with its nickname.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ObjectFactory

public ObjectFactory(Class clazz)
Constructor.

Parameters:
clazz - type which must be a supertype of any class registered with this factory
Method Detail

getFactoryClass

public Class getFactoryClass()
Returns the class of which any object created by this factory is guaranteed to be an instance.

Returns:
clazz

register

public void register(String nickName,
                     String className)
Registers a class with its nickname.

Parameters:
nickName - nickname
className - fully-qualified class name

getNickNames

public String[] getNickNames()
Returns a list of the nicknames which have been registered.

Returns:
nickname array

isRegistered

public boolean isRegistered(String name)
Indicates whether this factory knows about a given name. This may either be a registered nickname or a fully qualified classname for a class which is a subclass of this factory's produced class.

Parameters:
name - name
Returns:
true iff name can sensibly be passed to createObject(java.lang.String)

createObject

public Object createObject(String name)
                    throws LoadException
Constructs and returns an object from one of the classes registered with this factory. If construction fails because the required class is not on the classpath or there is some error in class initialization, a LoadException is thrown. If the class is of the wrong sort (has no no-arg constructor, is not a subtype of this factory's supertype) a RuntimeException will be thrown.

Parameters:
name - classname/nickname of class to instantiate
Throws:
LoadException - if the load fails for unsurprising reasons

Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved.