Package org.apache.commons.collections4.functors

Class SwitchTransformer<T,R>

java.lang.Object

org.apache.commons.collections4.functors.SwitchTransformer<T,R>

Type Parameters:

T - the type of the input to the function.

R - the type of the result of the function.

All Implemented Interfaces:

java.io.Serializable, java.util.function.Function<T,R>, Transformer<T,R>

public class SwitchTransformer<T,R>
extends java.lang.Object
implements Transformer<T,R>, java.io.Serializable

Transformer implementation calls the transformer whose predicate returns true, like a switch statement.

Since:

3.0

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
SwitchTransformer(Predicate<? super T>[] predicates, Transformer<? super T,? extends R>[] transformers, Transformer<? super T,? extends R> defaultTransformer)	Constructor that performs no validation.

Method Summary

Modifier and Type	Method	Description
Transformer<? super T,? extends R>	getDefaultTransformer()	Gets the default transformer.
Predicate<? super T>[]	getPredicates()	Gets the predicates.
Transformer<? super T,? extends R>[]	getTransformers()	Gets the transformers.
static <I,O> Transformer<I,O>	switchTransformer(java.util.Map<? extends Predicate<? super I>,? extends Transformer<? super I,? extends O>> map)	Create a new Transformer that calls one of the transformers depending on the predicates.
static <I,O> Transformer<I,O>	switchTransformer(Predicate<? super I>[] predicates, Transformer<? super I,? extends O>[] transformers, Transformer<? super I,? extends O> defaultTransformer)	Factory method that performs validation and copies the parameter arrays.
R	transform(T input)	Transforms the input to result by calling the transformer whose matching predicate returns true.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.function.Function

andThen, compose

Methods inherited from interface org.apache.commons.collections4.Transformer

apply

Constructor Detail

SwitchTransformer

public SwitchTransformer(Predicate<? super T>[] predicates,
                         Transformer<? super T,? extends R>[] transformers,
                         Transformer<? super T,? extends R> defaultTransformer)

Constructor that performs no validation. Use switchTransformer if you want that.

Parameters:

predicates - array of predicates, cloned, no nulls

transformers - matching array of transformers, cloned, no nulls

defaultTransformer - the transformer to use if no match, null means return null

Method Detail

switchTransformer

public static <I,O> Transformer<I,O> switchTransformer(java.util.Map<? extends Predicate<? super I>,? extends Transformer<? super I,? extends O>> map)

Create a new Transformer that calls one of the transformers depending on the predicates.

The Map consists of Predicate keys and Transformer values. A transformer is called if its matching predicate returns true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, the default transformer is called. The default transformer is set in the map with a null key. The ordering is that of the iterator() method on the entryset collection of the map.

Type Parameters:

I - the input type

O - the output type

Parameters:

map - a map of predicates to transformers

Returns:

the switch transformer

Throws:

java.lang.NullPointerException - if the map is null

java.lang.NullPointerException - if any transformer in the map is null

java.lang.ClassCastException - if the map elements are of the wrong type

switchTransformer

public static <I,O> Transformer<I,O> switchTransformer(Predicate<? super I>[] predicates,
                                                                   Transformer<? super I,? extends O>[] transformers,
                                                                   Transformer<? super I,? extends O> defaultTransformer)

Factory method that performs validation and copies the parameter arrays.

Type Parameters:

I - the input type

O - the output type

Parameters:

predicates - array of predicates, cloned, no nulls

transformers - matching array of transformers, cloned, no nulls

defaultTransformer - the transformer to use if no match, null means return null

Returns:

the chained transformer

Throws:

java.lang.NullPointerException - if either array is null

java.lang.NullPointerException - if any element in the arrays is null

java.lang.IllegalArgumentException - if the arrays have different sizes

getDefaultTransformer

public Transformer<? super T,? extends R> getDefaultTransformer()

Gets the default transformer.

Returns:

the default transformer

Since:

3.1

getPredicates

public Predicate<? super T>[] getPredicates()

Gets the predicates.

Returns:

a copy of the predicates

Since:

3.1

getTransformers

public Transformer<? super T,? extends R>[] getTransformers()

Gets the transformers.

Returns:

a copy of the transformers

Since:

3.1

transform

public R transform(T input)

Transforms the input to result by calling the transformer whose matching predicate returns true.

Specified by:

transform in interface Transformer<T,R>

Parameters:

input - the input object to transform

Returns:

the transformed result