Package org.apache.commons.collections

Class FactoryUtils

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: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
Author:
Stephen Colebourne

  • Constructor Details

    • FactoryUtils

      public FactoryUtils()
      This class is not normally instantiated.

  • Method Details

    • 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:

    • 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

      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:

    • 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:

      • 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

        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: