org.apache.commons.functor.core
Class Identity<T>

java.lang.Object
  extended by org.apache.commons.functor.core.Identity<T>
Type Parameters:
T - the returned value type.
All Implemented Interfaces:
Serializable, Functor, UnaryFunction<T,T>, UnaryFunctor<T>, UnaryPredicate<T>

public final class Identity<T>
extends Object
implements UnaryFunction<T,T>, UnaryPredicate<T>, Serializable

Evaluates to its input argument. Tests to the boolean value of the Boolean-valued parameter. The test(java.lang.Object) method throws an exception if the parameter isn't a non-null Boolean.

Version:
$Revision: 1160385 $ $Date: 2011-08-22 21:28:37 +0200 (Mon, 22 Aug 2011) $
Author:
Rodney Waldhoff
See Also:
Serialized Form

Field Summary
static Identity<Object> INSTANCE
          A generic Identity<Object> instance.
 
Constructor Summary
Identity()
          Create a new Identity.
 
Method Summary
 boolean equals(Object that)
          Indicates whether some other object is "equal to" this functor.
 T evaluate(T obj)
          Evaluate this function.
 int hashCode()
          Returns a hash code for this functor adhering to the general Object.hashCode contract.
static
<T> Identity<T>
instance()
          Get an Identity instance.
 boolean test(Boolean bool)
          Test a Boolean object by returning its booleanValue.
 boolean test(Object obj)
          Evaluate this predicate.
 String toString()
          Returns a human readable description of this functor.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

INSTANCE

public static final Identity<Object> INSTANCE
A generic Identity<Object> instance.

Constructor Detail

Identity

public Identity()
Create a new Identity.

Method Detail

evaluate

public T evaluate(T obj)
Evaluate this function.

Specified by:
evaluate in interface UnaryFunction<T,T>
Parameters:
obj - the A object to evaluate
Returns:
the T result of this evaluation

test

public boolean test(Object obj)
Evaluate this predicate.

Specified by:
test in interface UnaryPredicate<T>
Parameters:
obj - the A object to test
Returns:
the result of this test

test

public boolean test(Boolean bool)
Test a Boolean object by returning its booleanValue.

Parameters:
bool - Boolean
Returns:
boolean

equals

public boolean equals(Object that)
Indicates whether some other object is "equal to" this functor. This method must adhere to general Object.equals contract. Additionally, this method can return true only if the specified Object implements the same functor interface and is known to produce the same results and/or side-effects for the same arguments (if any).

While implementators are strongly encouraged to override the default Object implementation of this method, note that the default Object implementation does in fact adhere to the functor equals contract.

Specified by:
equals in interface Functor
Overrides:
equals in class Object
Parameters:
that - the object to compare this functor to
Returns:
true iff the given object implements this functor interface, and is known to produce the same results and/or side-effects for the same arguments (if any).
See Also:
Functor.hashCode()

hashCode

public int hashCode()
Returns a hash code for this functor adhering to the general Object.hashCode contract. Implementators are strongly encouraged but not strictly required to override the default Object implementation of this method.

Specified by:
hashCode in interface Functor
Overrides:
hashCode in class Object
Returns:
a hash code for this functor
See Also:
Functor.equals(java.lang.Object)

toString

public String toString()
Returns a human readable description of this functor. Implementators are strongly encouraged but not strictly required to override the default Object implementation of this method.

Specified by:
toString in interface Functor
Overrides:
toString in class Object
Returns:
a human readable description of this functor

instance

public static <T> Identity<T> instance()
Get an Identity instance.

Type Parameters:
T - the identity returned value type.
Returns:
Identity


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