Package org.apache.commons.collections4.collection

Class TransformedCollection<E>

java.lang.Object

org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>

org.apache.commons.collections4.collection.TransformedCollection<E>

Type Parameters:

E - The type of the elements in the collection.

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>

Direct Known Subclasses:

TransformedBag, TransformedList, TransformedMultiSet, TransformedQueue, TransformedSet

public class TransformedCollection<E>
extends AbstractCollectionDecorator<E>

Decorates another Collection to transform objects that are added.

The add methods are affected by this class. Thus objects must be removed or searched for using their transformed form. For example, if the transformation converts Strings to Integers, you must use the Integer form to remove objects.

This class is Serializable from Commons Collections 3.1.

Since:

3.0

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected final Transformer<? super E,? extends E>	transformer	The transformer to use

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	TransformedCollection(Collection<E> collection, Transformer<? super E,? extends E> transformer)	Constructs and wraps (not copies).

Method Summary

Modifier and Type	Method	Description
boolean	add(E object)
boolean	addAll(Collection<? extends E> coll)
protected E	transform(E object)	Transforms an object.
protected Collection<E>	transform(Collection<? extends E> coll)	Transforms a collection.
static <E> TransformedCollection<E>	transformedCollection(Collection<E> collection, Transformer<? super E,? extends E> transformer)	Creates a transforming collection that will transform existing contents of the specified collection.
static <E> TransformedCollection<E>	transformingCollection(Collection<E> coll, Transformer<? super E,? extends E> transformer)	Creates a transforming collection.

Methods inherited from class org.apache.commons.collections4.collection.AbstractCollectionDecorator

clear, contains, containsAll, decorated, isEmpty, iterator, remove, removeAll, removeIf, retainAll, setCollection, size, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

equals, hashCode, parallelStream, spliterator, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Details

transformer

protected final Transformer<? super E,? extends E> transformer

The transformer to use

Constructor Details

TransformedCollection

protected TransformedCollection(Collection<E> collection,
 Transformer<? super E,? extends E> transformer)

Constructs and wraps (not copies).

If there are any elements already in the collection being decorated, they are NOT transformed.

Parameters:

collection - The collection to decorate, must not be null.

transformer - The transformer to use for conversion, must not be null.

Throws:

NullPointerException - if collection or transformer is null.

Method Details

transformedCollection

public static <E> TransformedCollection<E> transformedCollection(Collection<E> collection,
 Transformer<? super E,? extends E> transformer)

Creates a transforming collection that will transform existing contents of the specified collection.

If there are any elements already in the collection being decorated, they will be transformed by this method. Contrast this with transformingCollection(Collection, Transformer).

Type Parameters:

E - The type of the elements in the collection.

Parameters:

collection - The collection to decorate, must not be null.

transformer - The transformer to use for conversion, must not be null.

Returns:

A new transformed Collection.

Throws:

NullPointerException - if collection or transformer is null.

Since:

4.0

transformingCollection

public static <E> TransformedCollection<E> transformingCollection(Collection<E> coll,
 Transformer<? super E,? extends E> transformer)

Creates a transforming collection.

If there are any elements already in the collection being decorated, they are NOT transformed. Contrast this with transformedCollection(Collection, Transformer).

Type Parameters:

E - The type of the elements in the collection.

Parameters:

coll - The collection to decorate, must not be null.

transformer - The transformer to use for conversion, must not be null.

Returns:

A new transformed collection.

Throws:

NullPointerException - if collection or transformer is null.

Since:

4.0

add

public boolean add(E object)

Specified by:

add in interface Collection<E>

Overrides:

add in class AbstractCollectionDecorator<E>

addAll

public boolean addAll(Collection<? extends E> coll)

Specified by:

addAll in interface Collection<E>

Overrides:

addAll in class AbstractCollectionDecorator<E>

transform

protected Collection<E> transform(Collection<? extends E> coll)

Transforms a collection.

The transformer itself may throw an exception if necessary.

Parameters:

coll - The collection to transform.

Returns:

A transformed object.

transform

protected E transform(E object)

Transforms an object.

The transformer itself may throw an exception if necessary.

Parameters:

object - The object to transform.

Returns:

A transformed object.