[COLLECTIONS-530] Added Builder for PredicatedCollection. Thanks to Erik.
git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1654518 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Thomas Neidhart
parent
5d42c95c33
commit
dd5e51e5b3
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@ -22,6 +22,11 @@
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<body>
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<release version="4.1" date="TBD" description="">
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<action issue="COLLECTIONS-530" dev="tn" type="fix" due-to="Erik">
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Added a Builder for "PredicatedCollection". Elements added to the builder
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that fail the predicate will not throw an IllegalArgumentException. The builder
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supports creating predicated lists, bags, sets and queues.
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</action>
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<action issue="COLLECTIONS-545" dev="tn" type="fix" due-to="Oswaldo Olivo">
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Documented runtime complexity of "CollectionUtils#removeAll(Collection, Collection).
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</action>
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@ -16,9 +16,23 @@
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*/
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package org.apache.commons.collections4.collection;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.HashSet;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Queue;
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import java.util.Set;
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import org.apache.commons.collections4.Bag;
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import org.apache.commons.collections4.Predicate;
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import org.apache.commons.collections4.bag.HashBag;
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import org.apache.commons.collections4.bag.PredicatedBag;
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import org.apache.commons.collections4.functors.NotNullPredicate;
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import org.apache.commons.collections4.list.PredicatedList;
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import org.apache.commons.collections4.queue.PredicatedQueue;
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import org.apache.commons.collections4.set.PredicatedSet;
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/**
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* Decorates another {@link Collection} to validate that additions
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@ -28,8 +42,10 @@ import org.apache.commons.collections4.Predicate;
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* It is normally created to decorate an empty collection.
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* If an object cannot be added to the collection, an IllegalArgumentException is thrown.
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* <p>
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* One usage would be to ensure that no null entries are added to the collection.
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* <pre>Collection coll = PredicatedCollection.decorate(new ArrayList(), NotNullPredicate.INSTANCE);</pre>
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* One usage would be to ensure that no null entries are added to the collection:
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* <pre>
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* Collection coll = PredicatedCollection.predicatedCollection(new ArrayList(), NotNullPredicate.INSTANCE);
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* </pre>
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* <p>
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* This class is Serializable from Commons Collections 3.1.
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*
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@ -45,6 +61,29 @@ public class PredicatedCollection<E> extends AbstractCollectionDecorator<E> {
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/** The predicate to use */
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protected final Predicate<? super E> predicate;
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/**
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* Returns a Builder with the given predicate.
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*
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* @param <E> the element type
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* @param predicate the predicate to use
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* @return a new Builder for predicated collections
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* @since 4.1
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*/
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public static <E> Builder<E> builder(final Predicate<? super E> predicate) {
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return new Builder<E>(predicate);
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}
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/**
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* Returns a Builder with a NotNullPredicate.
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*
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* @param <E> the element type
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* @return a new Builder for predicated collections that ignores null values.
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* @since 4.1
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*/
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public static <E> Builder<E> notNullBuilder() {
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return new Builder<E>(NotNullPredicate.<E>notNullPredicate());
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}
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/**
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* Factory method to create a predicated (validating) collection.
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* <p>
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@ -135,4 +174,230 @@ public class PredicatedCollection<E> extends AbstractCollectionDecorator<E> {
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return decorated().addAll(coll);
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}
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/**
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* Builder for creating predicated collections.
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* <p>
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* Create a Builder with a predicate to validate elements against, then add any elements
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* to the builder. Elements that fail the predicate will be added to a rejected list.
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* Finally create or decorate a collection using the createPredicated[List,Set,Bag,Queue] methods.
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* <p>
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* An example:
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* <pre>
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* Predicate<String> predicate = NotNullPredicate.notNullPredicate();
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* PredicatedCollectionBuilder<String> builder = PredicatedCollection.builder(predicate);
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* builder.add("item1");
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* builder.add(null);
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* builder.add("item2");
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* List<String> predicatedList = builder.createPredicatedList();
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* </pre>
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* <p>
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* At the end of the code fragment above predicatedList is protected by the predicate supplied
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* to the builder and it contains item1 and item2.
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* <p>
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* More elements can be added to the builder once a predicated collection has been created,
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* but these elements will not be reflected in already created collections.
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*
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* @param <E> the element type
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* @since 4.1
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*/
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public static class Builder<E> {
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/** The predicate to use. */
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private final Predicate<? super E> predicate;
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/** The buffer containing valid elements. */
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private final List<E> accepted = new ArrayList<E>();
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/** The buffer containing rejected elements. */
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private final List<E> rejected = new ArrayList<E>();
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// -----------------------------------------------------------------------
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/**
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* Constructs a PredicatedCollectionBuilder with the specified Predicate.
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*
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* @param predicate the predicate to use
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* @throws IllegalArgumentException if predicate is null
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*/
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public Builder(final Predicate<? super E> predicate) {
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if (predicate == null) {
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throw new IllegalArgumentException("Predicate must not be null");
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}
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this.predicate = predicate;
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}
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/**
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* Adds the item to the builder.
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* <p>
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* If the predicate is true, it is added to the list of accepted elements,
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* otherwise it is added to the rejected list.
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*
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* @param item the element to add
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* @return the PredicatedCollectionBuilder.
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*/
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public Builder<E> add(final E item) {
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if (predicate.evaluate(item)) {
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accepted.add(item);
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} else {
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rejected.add(item);
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}
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return this;
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}
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/**
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* Adds all elements from the given collection to the builder.
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* <p>
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* All elements for which the predicate evaluates to true will be added to the
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* list of accepted elements, otherwise they are added to the rejected list.
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*
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* @param items the elements to add to the builder
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* @return the PredicatedCollectionBuilder.
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*/
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public Builder<E> addAll(final Collection<? extends E> items) {
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if (items != null) {
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for (E item : items) {
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add(item);
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}
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}
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return this;
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}
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/**
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* Create a new predicated list filled with the accepted elements.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned list.
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*
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* @return a new predicated list.
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*/
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public List<E> createPredicatedList() {
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return createPredicatedList(new ArrayList<E>());
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}
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/**
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* Decorates the given list with validating behavior using the predicate. All accepted elements
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* are appended to the list. If the list already contains elements, they are validated.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned list.
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*
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* @param list the List to decorate, must not be null
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* @return the decorated list.
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* @throws IllegalArgumentException if list is null or contains invalid elements
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*/
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public List<E> createPredicatedList(final List<E> list) {
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if (list == null) {
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throw new IllegalArgumentException("list must not be null");
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}
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final List<E> predicatedList = PredicatedList.predicatedList(list, predicate);
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predicatedList.addAll(accepted);
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return predicatedList;
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}
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/**
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* Create a new predicated set filled with the accepted elements.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned set.
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*
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* @return a new predicated set.
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*/
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public Set<E> createPredicatedSet() {
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return createPredicatedSet(new HashSet<E>());
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}
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/**
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* Decorates the given list with validating behavior using the predicate. All accepted elements
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* are appended to the set. If the set already contains elements, they are validated.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned set.
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*
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* @param set the set to decorate, must not be null
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* @return the decorated set.
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* @throws IllegalArgumentException if set is null or contains invalid elements
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*/
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public Set<E> createPredicatedSet(final Set<E> set) {
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if (set == null) {
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throw new IllegalArgumentException("set must not be null");
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}
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final PredicatedSet<E> predicatedSet = PredicatedSet.predicatedSet(set, predicate);
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predicatedSet.addAll(accepted);
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return predicatedSet;
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}
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/**
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* Create a new predicated bag filled with the accepted elements.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned bag.
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*
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* @return a new predicated bag.
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*/
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public Bag<E> createPredicatedBag() {
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return createPredicatedBag(new HashBag<E>());
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}
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/**
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* Decorates the given bag with validating behavior using the predicate. All accepted elements
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* are appended to the bag. If the bag already contains elements, they are validated.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned bag.
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*
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* @param bag the bag to decorate, must not be null
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* @return the decorated bag.
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* @throws IllegalArgumentException if bag is null or contains invalid elements
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*/
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public Bag<E> createPredicatedBag(final Bag<E> bag) {
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if (bag == null) {
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throw new IllegalArgumentException("bag must not be null");
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}
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final PredicatedBag<E> predicatedBag = PredicatedBag.predicatedBag(bag, predicate);
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predicatedBag.addAll(accepted);
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return predicatedBag;
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}
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/**
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* Create a new predicated queue filled with the accepted elements.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned queue.
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*
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* @return a new predicated queue.
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*/
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public Queue<E> createPredicatedQueue() {
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return createPredicatedQueue(new LinkedList<E>());
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}
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/**
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* Decorates the given queue with validating behavior using the predicate. All accepted elements
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* are appended to the queue. If the queue already contains elements, they are validated.
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* <p>
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* The builder is not modified by this method, so it is possible to create more collections
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* or add more elements afterwards. Further changes will not propagate to the returned queue.
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*
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* @param queue the queue to decorate, must not be null
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* @return the decorated queue.
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* @throws IllegalArgumentException if queue is null or contains invalid elements
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*/
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public Queue<E> createPredicatedQueue(final Queue<E> queue) {
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if (queue == null) {
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throw new IllegalArgumentException("queue must not be null");
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}
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final PredicatedQueue<E> predicatedQueue = PredicatedQueue.predicatedQueue(queue, predicate);
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predicatedQueue.addAll(accepted);
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return predicatedQueue;
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}
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/**
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* Returns an unmodifiable collection containing all rejected elements.
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*
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* @return an unmodifiable collection
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*/
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public Collection<E> rejectedElements() {
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return Collections.unmodifiableCollection(rejected);
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}
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}
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}
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@ -0,0 +1,144 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.collections4.collection;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.List;
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import java.util.Queue;
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import java.util.Set;
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import org.apache.commons.collections4.Bag;
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import org.apache.commons.collections4.Predicate;
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import org.junit.Assert;
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import org.junit.Test;
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/**
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* Tests the PredicatedCollection.Builder class.
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*
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* @since 4.1
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* @version $Id$
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*/
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public class PredicatedCollectionBuilderTest {
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/**
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* Verify that passing the Predicate means ending up in the buffer.
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*/
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@Test
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public void addPass() {
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PredicatedCollection.Builder<String> builder = PredicatedCollection.notNullBuilder();
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builder.add("test");
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Assert.assertEquals(builder.createPredicatedList().size(), 1);
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}
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/**
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* Verify that failing the Predicate means NOT ending up in the buffer.
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*/
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@Test
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public void addFail() {
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PredicatedCollection.Builder<String> builder = PredicatedCollection.notNullBuilder();
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builder.add((String) null);
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Assert.assertTrue(builder.createPredicatedList().isEmpty());
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Assert.assertEquals(1, builder.rejectedElements().size());
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}
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/**
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* Verify that only items that pass the Predicate end up in the buffer.
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*/
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@Test
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public void addAllPass() {
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PredicatedCollection.Builder<String> builder = PredicatedCollection.notNullBuilder();
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builder.addAll(Arrays.asList("test1", null, "test2"));
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Assert.assertEquals(builder.createPredicatedList().size(), 2);
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}
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@Test
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public void createPredicatedCollectionWithNotNullPredicate() {
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PredicatedCollection.Builder<String> builder = PredicatedCollection.notNullBuilder();
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builder.add("test1");
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builder.add((String) null);
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List<String> predicatedList = builder.createPredicatedList();
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checkPredicatedCollection1(predicatedList);
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Set<String> predicatedSet = builder.createPredicatedSet();
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checkPredicatedCollection1(predicatedSet);
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Bag<String> predicatedBag = builder.createPredicatedBag();
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checkPredicatedCollection1(predicatedBag);
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Queue<String> predicatedQueue = builder.createPredicatedQueue();
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checkPredicatedCollection1(predicatedQueue);
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}
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private void checkPredicatedCollection1(final Collection<String> collection) {
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Assert.assertEquals(1, collection.size());
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collection.add("test2");
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Assert.assertEquals(2, collection.size());
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try {
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collection.add(null);
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Assert.fail("Expecting IllegalArgumentException for failing predicate!");
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} catch (IllegalArgumentException iae) {
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// expected
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}
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}
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@Test
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public void createPredicatedCollectionWithPredicate() {
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OddPredicate p = new OddPredicate();
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PredicatedCollection.Builder<Integer> builder = PredicatedCollection.builder(p);
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builder.add(1);
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builder.add(2);
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builder.add(3);
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List<Integer> predicatedList = builder.createPredicatedList();
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checkPredicatedCollection2(predicatedList);
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Set<Integer> predicatedSet = builder.createPredicatedSet();
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checkPredicatedCollection2(predicatedSet);
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Bag<Integer> predicatedBag = builder.createPredicatedBag();
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checkPredicatedCollection2(predicatedBag);
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Queue<Integer> predicatedQueue = builder.createPredicatedQueue();
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checkPredicatedCollection2(predicatedQueue);
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}
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private void checkPredicatedCollection2(final Collection<Integer> collection) {
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Assert.assertEquals(2, collection.size());
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try {
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collection.add(4);
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Assert.fail("Expecting IllegalArgumentException for failing predicate!");
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} catch (IllegalArgumentException iae) {
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}
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Assert.assertEquals(2, collection.size());
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collection.add(5);
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Assert.assertEquals(3, collection.size());
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}
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private static class OddPredicate implements Predicate<Integer> {
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public boolean evaluate(Integer value) {
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return value % 2 == 1;
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}
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}
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}
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