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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.collections4.list;
import java.util.Collection;
import java.util.List;
import java.util.ListIterator;
import org.apache.commons.collections4.Transformer;
import org.apache.commons.collections4.collection.TransformedCollection;
import org.apache.commons.collections4.iterators.AbstractListIteratorDecorator;
/**
* Decorates another List to transform objects that are added.
*
* The add and set 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
*/
public class TransformedList extends TransformedCollection implements List {
/** Serialization version */
private static final long serialVersionUID = 1077193035000013141L;
/**
* Factory method to create a transforming list.
*
* If there are any elements already in the list being decorated, they
* are NOT transformed.
* Contrast this with {@link #transformedList(List, Transformer)}.
*
* @param the type of the elements in the list
* @param list the list to decorate, must not be null
* @param transformer the transformer to use for conversion, must not be null
* @return a new transformed list
* @throws NullPointerException if list or transformer is null
* @since 4.0
*/
public static TransformedList transformingList(final List list,
final Transformer transformer) {
return new TransformedList<>(list, transformer);
}
/**
* Factory method to create a transforming list that will transform
* existing contents of the specified list.
*
* If there are any elements already in the list being decorated, they
* will be transformed by this method.
* Contrast this with {@link #transformingList(List, Transformer)}.
*
* @param the type of the elements in the list
* @param list the list to decorate, must not be null
* @param transformer the transformer to use for conversion, must not be null
* @return a new transformed List
* @throws NullPointerException if list or transformer is null
* @since 4.0
*/
public static TransformedList transformedList(final List list,
final Transformer transformer) {
final TransformedList decorated = new TransformedList<>(list, transformer);
if (list.size() > 0) {
@SuppressWarnings("unchecked") // list is of type E
final E[] values = (E[]) list.toArray(); // NOPMD - false positive for generics
list.clear();
for (final E value : values) {
decorated.decorated().add(transformer.transform(value));
}
}
return decorated;
}
//-----------------------------------------------------------------------
/**
* Constructor that wraps (not copies).
*
* If there are any elements already in the list being decorated, they
* are NOT transformed.
*
* @param list the list to decorate, must not be null
* @param transformer the transformer to use for conversion, must not be null
* @throws NullPointerException if list or transformer is null
*/
protected TransformedList(final List list, final Transformer transformer) {
super(list, transformer);
}
/**
* Gets the decorated list.
*
* @return the decorated list
*/
protected List getList() {
return (List) decorated();
}
@Override
public boolean equals(final Object object) {
return object == this || decorated().equals(object);
}
@Override
public int hashCode() {
return decorated().hashCode();
}
//-----------------------------------------------------------------------
@Override
public E get(final int index) {
return getList().get(index);
}
@Override
public int indexOf(final Object object) {
return getList().indexOf(object);
}
@Override
public int lastIndexOf(final Object object) {
return getList().lastIndexOf(object);
}
@Override
public E remove(final int index) {
return getList().remove(index);
}
//-----------------------------------------------------------------------
@Override
public void add(final int index, E object) {
object = transform(object);
getList().add(index, object);
}
@Override
public boolean addAll(final int index, Collection coll) {
coll = transform(coll);
return getList().addAll(index, coll);
}
@Override
public ListIterator listIterator() {
return listIterator(0);
}
@Override
public ListIterator listIterator(final int i) {
return new TransformedListIterator(getList().listIterator(i));
}
@Override
public E set(final int index, E object) {
object = transform(object);
return getList().set(index, object);
}
@Override
public List subList(final int fromIndex, final int toIndex) {
final List sub = getList().subList(fromIndex, toIndex);
return new TransformedList<>(sub, transformer);
}
/**
* Inner class Iterator for the TransformedList
*/
protected class TransformedListIterator extends AbstractListIteratorDecorator {
/**
* Create a new transformed list iterator.
*
* @param iterator the list iterator to decorate
*/
protected TransformedListIterator(final ListIterator iterator) {
super(iterator);
}
@Override
public void add(E object) {
object = transform(object);
getListIterator().add(object);
}
@Override
public void set(E object) {
object = transform(object);
getListIterator().set(object);
}
}
}