public class

FactoryUtils

extends Object
java.lang.Object
   ↳ org.apache.commons.collections.FactoryUtils

Class Overview

FactoryUtils provides reference implementations and utilities for the Factory functor interface. The supplied factories are:

  • Prototype - clones a specified object
  • Reflection - creates objects using reflection
  • Constant - always returns the same object
  • Null - always returns null
  • Exception - always throws an exception
All the supplied factories are Serializable.

Summary

Public Constructors
FactoryUtils()
This class is not normally instantiated.
Public Methods
static Factory constantFactory(Object constantToReturn)
Creates a Factory that will return the same object each time the factory is used.
static Factory exceptionFactory()
Gets a Factory that always throws an exception.
static Factory instantiateFactory(Class classToInstantiate, Class[] paramTypes, Object[] args)
Creates a Factory that can create objects of a specific type using the arguments specified to this method.
static Factory instantiateFactory(Class classToInstantiate)
Creates a Factory that can create objects of a specific type using a no-args constructor.
static Factory nullFactory()
Gets a Factory that will return null each time the factory is used.
static Factory prototypeFactory(Object prototype)
Creates a Factory that will return a clone of the same prototype object each time the factory is used.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public FactoryUtils ()

This class is not normally instantiated.

Public Methods

public static Factory constantFactory (Object constantToReturn)

Creates a Factory that will return the same object each time the factory is used. No check is made that the object is immutable. In general, only immutable objects should use the constant factory. Mutable objects should use the prototype factory.

Parameters
constantToReturn the constant object to return each time in the factory
Returns
  • the constant factory.
See Also

public static Factory exceptionFactory ()

Gets a Factory that always throws an exception. This could be useful during testing as a placeholder.

Returns
  • the factory
See Also

public static Factory instantiateFactory (Class classToInstantiate, Class[] paramTypes, Object[] args)

Creates a Factory that can create objects of a specific type using the arguments specified to this method.

Parameters
classToInstantiate the Class to instantiate each time in the factory
paramTypes parameter types for the constructor, can be null
args the arguments to pass to the constructor, can be null
Returns
  • the reflection factory
Throws
IllegalArgumentException if the classToInstantiate is null
IllegalArgumentException if the paramTypes and args don't match
IllegalArgumentException if the constructor doesn't exist
See Also

public static Factory instantiateFactory (Class classToInstantiate)

Creates a Factory that can create objects of a specific type using a no-args constructor.

Parameters
classToInstantiate the Class to instantiate each time in the factory
Returns
  • the reflection factory
Throws
IllegalArgumentException if the classToInstantiate is null
See Also

public static Factory nullFactory ()

Gets a Factory that will return null each time the factory is used. This could be useful during testing as a placeholder.

Returns
  • the factory
See Also

public static Factory prototypeFactory (Object prototype)

Creates a Factory that will return a clone of the same prototype object each time the factory is used. The prototype will be cloned using one of these techniques (in order):

  • public clone method
  • public copy constructor
  • serialization clone

Parameters
prototype the object to clone each time in the factory
Returns
  • the prototype factory
Throws
IllegalArgumentException if the prototype is null
IllegalArgumentException if the prototype cannot be cloned
See Also