Package org.apache.commons.functor.core

Class Identity<T>

java.lang.Object

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

Type Parameters:

T - the returned value type.

All Implemented Interfaces:

java.io.Serializable, Functor, UnaryFunction<T,T>, UnaryFunctor<T>, UnaryPredicate<T>

public final class Identity<T>
extends java.lang.Object
implements UnaryFunction<T,T>, UnaryPredicate<T>, java.io.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:

$Revision$ $Date$

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static Identity<java.lang.Object>	INSTANCE	A generic Identity<Object> instance.
private static long	serialVersionUID	serialVersionUID declaration.

Constructor Summary

Constructors

Constructor	Description
Identity()	Create a new Identity.

Method Summary

Modifier and Type	Method	Description
boolean	equals(java.lang.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(java.lang.Boolean bool)	Test a Boolean object by returning its booleanValue.
boolean	test(java.lang.Object obj)	Evaluate this predicate.
java.lang.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<java.lang.Object> INSTANCE

A generic Identity<Object> instance.

serialVersionUID

private static final long serialVersionUID

serialVersionUID declaration.

See Also:

Constant Field Values

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(java.lang.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(java.lang.Boolean bool)

Test a Boolean object by returning its booleanValue.

Parameters:

bool - Boolean

Returns:

boolean

equals

public boolean equals(java.lang.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 java.lang.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 java.lang.Object

Returns:

a hash code for this functor

See Also:

Functor.equals(java.lang.Object)

toString

public java.lang.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 java.lang.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