FactoryUtils (Apache Commons Collections 3.2.2 API)

java.lang.Object
- org.apache.commons.collections.FactoryUtils

```
public class FactoryUtils
extends Object
```
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.
Since:

Commons Collections 3.0

Version:

$Revision: 972404 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne

Constructor Summary

Constructors
Constructor and Description

FactoryUtils()
This class is not normally instantiated.

Constructors
Constructor and Description
`FactoryUtils()` This class is not normally instantiated.

Method Summary

Methods
Modifier and Type	Method and Description
`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)` Creates a Factory that can create objects of a specific type using a no-args constructor.
`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`	`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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - FactoryUtils
```
public FactoryUtils()
```
    This class is not normally instantiated.
- Method Detail
  - exceptionFactory
```
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:
    ExceptionFactory
  - nullFactory
```
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:
    ConstantFactory
  - constantFactory
```
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:
    ConstantFactory
  - prototypeFactory
```
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:
    PrototypeFactory
  - instantiateFactory
```
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:
    InstantiateFactory
  - instantiateFactory
```
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:
    InstantiateFactory

Class FactoryUtils

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

FactoryUtils

Method Detail

exceptionFactory

nullFactory

constantFactory

prototypeFactory

instantiateFactory

instantiateFactory