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[COLLECTIONS-466] Replace Collection with Iterable where applicable in CollectionUtils. 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1481605 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Thomas Neidhart 2013-05-12 16:56:26 +00:00
parent 1194c69fb1
commit 709aa7bf9c
1 changed files with 49 additions and 47 deletions
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96
src/main/java/org/apache/commons/collections4/CollectionUtils.java
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@ -43,7 +43,8 @@ import org.apache.commons.collections4.iterators.PermutationIterator;
/** /**
* Provides utility methods and decorators for {@link Collection} instances. * Provides utility methods and decorators for {@link Collection} instances.
* Method parameters will take {@link Iterable} objects when possible. * <p>
* NOTE: From 4.0, method parameters will take {@link Iterable} objects when possible.
* *
* @since 1.0 * @since 1.0
* @version $Id$ * @version $Id$
@ -212,11 +213,11 @@ public class CollectionUtils {
/** /**
* Returns a {@link Collection} containing the union of the given * Returns a {@link Collection} containing the union of the given
* {@link Collection}s. * {@link Iterable}s.
* <p> * <p>
* The cardinality of each element in the returned {@link Collection} will * The cardinality of each element in the returned {@link Collection} will
* be equal to the maximum of the cardinality of that element in the two * be equal to the maximum of the cardinality of that element in the two
* given {@link Collection}s. * given {@link Iterable}s.
* *
* @param a the first collection, must not be null * @param a the first collection, must not be null
* @param b the second collection, must not be null * @param b the second collection, must not be null
@ -235,11 +236,11 @@ public class CollectionUtils {
/** /**
* Returns a {@link Collection} containing the intersection of the given * Returns a {@link Collection} containing the intersection of the given
* {@link Collection}s. * {@link Iterable}s.
* <p> * <p>
* The cardinality of each element in the returned {@link Collection} will * The cardinality of each element in the returned {@link Collection} will
* be equal to the minimum of the cardinality of that element in the two * be equal to the minimum of the cardinality of that element in the two
* given {@link Collection}s. * given {@link Iterable}s.
* *
* @param a the first collection, must not be null * @param a the first collection, must not be null
* @param b the second collection, must not be null * @param b the second collection, must not be null
@ -259,7 +260,7 @@ public class CollectionUtils {
/** /**
* Returns a {@link Collection} containing the exclusive disjunction * Returns a {@link Collection} containing the exclusive disjunction
* (symmetric difference) of the given {@link Collection}s. * (symmetric difference) of the given {@link Iterable}s.
* <p> * <p>
* The cardinality of each element <i>e</i> in the returned * The cardinality of each element <i>e</i> in the returned
* {@link Collection} will be equal to * {@link Collection} will be equal to
@ -432,12 +433,8 @@ public class CollectionUtils {
* Only those elements present in the collection will appear as * Only those elements present in the collection will appear as
* keys in the map. * keys in the map.
* *
* @param coll * @param <O> the type of object in the returned {@link Map}. This is a super type of <I>.
* the collection to get the cardinality map for, must not be * @param coll the collection to get the cardinality map for, must not be null
* null
* @param <O>
* the type of object in the returned {@link Map}. This is a
* super type of <I>.
* @return the populated cardinality map * @return the populated cardinality map
*/ */
public static <O> Map<O, Integer> getCardinalityMap(final Iterable<? extends O> coll) { public static <O> Map<O, Integer> getCardinalityMap(final Iterable<? extends O> coll) {
@ -638,12 +635,12 @@ public class CollectionUtils {
* If the input collection or predicate is null, or no element of the collection * If the input collection or predicate is null, or no element of the collection
* matches the predicate, null is returned. * matches the predicate, null is returned.
* *
* @param <T> the type of object the {@link Collection} contains * @param <T> the type of object the {@link Iterable} contains
* @param collection the collection to search, may be null * @param collection the collection to search, may be null
* @param predicate the predicate to use, may be null * @param predicate the predicate to use, may be null
* @return the first element of the collection which matches the predicate or null if none could be found * @return the first element of the collection which matches the predicate or null if none could be found
*/ */
public static <T> T find(final Collection<T> collection, final Predicate<? super T> predicate) { public static <T> T find(final Iterable<T> collection, final Predicate<? super T> predicate) {
if (collection != null && predicate != null) { if (collection != null && predicate != null) {
for (final T item : collection) { for (final T item : collection) {
if (predicate.evaluate(item)) { if (predicate.evaluate(item)) {
@ -659,13 +656,13 @@ public class CollectionUtils {
* <p> * <p>
* If the input collection or closure is null, there is no change made. * If the input collection or closure is null, there is no change made.
* *
* @param <T> the type of object the {@link Collection} contains * @param <T> the type of object the {@link Iterable} contains
* @param <C> the closure type * @param <C> the closure type
* @param collection the collection to get the input from, may be null * @param collection the collection to get the input from, may be null
* @param closure the closure to perform, may be null * @param closure the closure to perform, may be null
* @return closure * @return closure
*/ */
public static <T, C extends Closure<? super T>> C forAllDo(final Collection<T> collection, final C closure) { public static <T, C extends Closure<? super T>> C forAllDo(final Iterable<T> collection, final C closure) {
if (collection != null && closure != null) { if (collection != null && closure != null) {
for (final T element : collection) { for (final T element : collection) {
closure.execute(element); closure.execute(element);
@ -700,14 +697,14 @@ public class CollectionUtils {
* <p> * <p>
* If the input collection or closure is null, there is no change made. * If the input collection or closure is null, there is no change made.
* *
* @param <T> the type of object the {@link Collection} contains * @param <T> the type of object the {@link Iterable} contains
* @param <C> the closure type * @param <C> the closure type
* @param collection the collection to get the input from, may be null * @param collection the collection to get the input from, may be null
* @param closure the closure to perform, may be null * @param closure the closure to perform, may be null
* @return the last element in the collection, or null if either collection or closure is null * @return the last element in the collection, or null if either collection or closure is null
* @since 4.0 * @since 4.0
*/ */
public static <T, C extends Closure<? super T>> T forAllButLastDo(final Collection<T> collection, public static <T, C extends Closure<? super T>> T forAllButLastDo(final Iterable<T> collection,
final C closure) { final C closure) {
return collection != null && closure != null ? forAllButLastDo(collection.iterator(), closure) : null; return collection != null && closure != null ? forAllButLastDo(collection.iterator(), closure) : null;
} }
@ -794,7 +791,7 @@ public class CollectionUtils {
* may reduce in size due to calling this method. * may reduce in size due to calling this method.
* *
* @param <C> the type of object the {@link Collection} contains * @param <C> the type of object the {@link Collection} contains
* @param collection the {@link Iterable} to get the input from, may be null * @param collection the {@link Collection} to get the input from, may be null
* @param transformer the transformer to perform, may be null * @param transformer the transformer to perform, may be null
*/ */
public static <C> void transform(final Collection<C> collection, public static <C> void transform(final Collection<C> collection,
@ -865,15 +862,17 @@ public class CollectionUtils {
* <p> * <p>
* A <code>null</code> predicate matches no elements. * A <code>null</code> predicate matches no elements.
* *
* @param <O> the type of object the {@link Collection} contains * @param <O> the type of object the {@link Iterable} contains
* @param inputCollection the collection to get the input from, may not be null * @param inputCollection the collection to get the input from, may not be null
* @param predicate the predicate to use, may be null * @param predicate the predicate to use, may be null
* @return the elements matching the predicate (new list) * @return the elements matching the predicate (new list)
* @throws NullPointerException if the input collection is null * @throws NullPointerException if the input collection is null
*/ */
public static <O> Collection<O> select(final Collection<? extends O> inputCollection, public static <O> Collection<O> select(final Iterable<? extends O> inputCollection,
final Predicate<? super O> predicate) { final Predicate<? super O> predicate) {
return select(inputCollection, predicate, new ArrayList<O>(inputCollection.size())); final Collection<O> answer = inputCollection instanceof Collection<?> ?
new ArrayList<O>(((Collection<?>) inputCollection).size()) : new ArrayList<O>();
return select(inputCollection, predicate, answer);
} }
/** /**
@ -883,7 +882,7 @@ public class CollectionUtils {
* If the input collection or predicate is null, there is no change to the * If the input collection or predicate is null, there is no change to the
* output collection. * output collection.
* *
* @param <O> the type of object the {@link Collection} contains * @param <O> the type of object the {@link Iterable} contains
* @param <R> the type of the output {@link Collection} * @param <R> the type of the output {@link Collection}
* @param inputCollection the collection to get the input from, may be null * @param inputCollection the collection to get the input from, may be null
* @param predicate the predicate to use, may be null * @param predicate the predicate to use, may be null
@ -891,7 +890,7 @@ public class CollectionUtils {
* and predicate or not null * and predicate or not null
* @return the outputCollection * @return the outputCollection
*/ */
public static <O, R extends Collection<? super O>> R select(final Collection<? extends O> inputCollection, public static <O, R extends Collection<? super O>> R select(final Iterable<? extends O> inputCollection,
final Predicate<? super O> predicate, final R outputCollection) { final Predicate<? super O> predicate, final R outputCollection) {
if (inputCollection != null && predicate != null) { if (inputCollection != null && predicate != null) {
@ -911,15 +910,17 @@ public class CollectionUtils {
* If the input predicate is <code>null</code>, the result is an empty * If the input predicate is <code>null</code>, the result is an empty
* list. * list.
* *
* @param <O> the type of object the {@link Collection} contains * @param <O> the type of object the {@link Iterable} contains
* @param inputCollection the collection to get the input from, may not be null * @param inputCollection the collection to get the input from, may not be null
* @param predicate the predicate to use, may be null * @param predicate the predicate to use, may be null
* @return the elements <b>not</b> matching the predicate (new list) * @return the elements <b>not</b> matching the predicate (new list)
* @throws NullPointerException if the input collection is null * @throws NullPointerException if the input collection is null
*/ */
public static <O> Collection<O> selectRejected(final Collection<? extends O> inputCollection, public static <O> Collection<O> selectRejected(final Iterable<? extends O> inputCollection,
final Predicate<? super O> predicate) { final Predicate<? super O> predicate) {
return selectRejected(inputCollection, predicate, new ArrayList<O>(inputCollection.size())); final Collection<O> answer = inputCollection instanceof Collection<?> ?
new ArrayList<O>(((Collection<?>) inputCollection).size()) : new ArrayList<O>();
return selectRejected(inputCollection, predicate, answer);
} }
/** /**
@ -929,7 +930,7 @@ public class CollectionUtils {
* If the input predicate is <code>null</code>, no elements are added to * If the input predicate is <code>null</code>, no elements are added to
* <code>outputCollection</code>. * <code>outputCollection</code>.
* *
* @param <O> the type of object the {@link Collection} contains * @param <O> the type of object the {@link Iterable} contains
* @param <R> the type of the output {@link Collection} * @param <R> the type of the output {@link Collection}
* @param inputCollection the collection to get the input from, may be null * @param inputCollection the collection to get the input from, may be null
* @param predicate the predicate to use, may be null * @param predicate the predicate to use, may be null
@ -937,7 +938,7 @@ public class CollectionUtils {
* and predicate or not null * and predicate or not null
* @return outputCollection * @return outputCollection
*/ */
public static <O, R extends Collection<? super O>> R selectRejected(final Collection<? extends O> inputCollection, public static <O, R extends Collection<? super O>> R selectRejected(final Iterable<? extends O> inputCollection,
final Predicate<? super O> predicate, final R outputCollection) { final Predicate<? super O> predicate, final R outputCollection) {
if (inputCollection != null && predicate != null) { if (inputCollection != null && predicate != null) {
@ -956,18 +957,18 @@ public class CollectionUtils {
* <p> * <p>
* If the input transformer is null, the result is an empty list. * If the input transformer is null, the result is an empty list.
* *
* @param inputCollection the collection to get the input from, may not be null
* @param transformer the transformer to use, may be null
* @param <I> the type of object in the input collection * @param <I> the type of object in the input collection
* @param <O> the type of object in the output collection * @param <O> the type of object in the output collection
* @param inputCollection the collection to get the input from, may not be null
* @param transformer the transformer to use, may be null
* @return the transformed result (new list) * @return the transformed result (new list)
* @throws NullPointerException if the input collection is null * @throws NullPointerException if the input collection is null
*/ */
public static <I, O> Collection<O> collect(final Iterable<I> inputCollection, public static <I, O> Collection<O> collect(final Iterable<I> inputCollection,
final Transformer<? super I, ? extends O> transformer) { final Transformer<? super I, ? extends O> transformer) {
final ArrayList<O> answer = new ArrayList<O>(); final Collection<O> answer = inputCollection instanceof Collection<?> ?
collect(inputCollection, transformer, answer); new ArrayList<O>(((Collection<?>) inputCollection).size()) : new ArrayList<O>();
return answer; return collect(inputCollection, transformer, answer);
} }
/** /**
@ -985,9 +986,7 @@ public class CollectionUtils {
*/ */
public static <I, O> Collection<O> collect(final Iterator<I> inputIterator, public static <I, O> Collection<O> collect(final Iterator<I> inputIterator,
final Transformer<? super I, ? extends O> transformer) { final Transformer<? super I, ? extends O> transformer) {
final ArrayList<O> answer = new ArrayList<O>(); return collect(inputIterator, transformer, new ArrayList<O>());
collect(inputIterator, transformer, answer);
return answer;
} }
/** /**
@ -997,13 +996,13 @@ public class CollectionUtils {
* If the input collection or transformer is null, there is no change to the * If the input collection or transformer is null, there is no change to the
* output collection. * output collection.
* *
* @param <I> the type of object in the input collection
* @param <O> the type of object in the output collection
* @param <R> the output type of the transformer - this extends O.
* @param inputCollection the collection to get the input from, may be null * @param inputCollection the collection to get the input from, may be null
* @param transformer the transformer to use, may be null * @param transformer the transformer to use, may be null
* @param outputCollection the collection to output into, may not be null if the inputCollection * @param outputCollection the collection to output into, may not be null if the inputCollection
* and transformer are not null * and transformer are not null
* @param <I> the type of object in the input collection
* @param <O> the type of object in the output collection
* @param <R> the output type of the transformer - this extends O.
* @return the outputCollection with the transformed input added * @return the outputCollection with the transformed input added
* @throws NullPointerException if the output collection is null and both, inputCollection and * @throws NullPointerException if the output collection is null and both, inputCollection and
* transformer are not null * transformer are not null
@ -1499,8 +1498,8 @@ public class CollectionUtils {
* @throws IllegalArgumentException if either collection is null * @throws IllegalArgumentException if either collection is null
* @since 4.0 * @since 4.0
*/ */
public static <O extends Comparable<? super O>> List<O> collate(Collection<? extends O> a, public static <O extends Comparable<? super O>> List<O> collate(Iterable<? extends O> a,
Collection<? extends O> b) { Iterable<? extends O> b) {
return collate(a, b, ComparatorUtils.<O>naturalComparator(), true); return collate(a, b, ComparatorUtils.<O>naturalComparator(), true);
} }
@ -1520,8 +1519,8 @@ public class CollectionUtils {
* @throws IllegalArgumentException if either collection is null * @throws IllegalArgumentException if either collection is null
* @since 4.0 * @since 4.0
*/ */
public static <O extends Comparable<? super O>> List<O> collate(final Collection<? extends O> a, public static <O extends Comparable<? super O>> List<O> collate(final Iterable<? extends O> a,
final Collection<? extends O> b, final Iterable<? extends O> b,
final boolean includeDuplicates) { final boolean includeDuplicates) {
return collate(a, b, ComparatorUtils.<O>naturalComparator(), includeDuplicates); return collate(a, b, ComparatorUtils.<O>naturalComparator(), includeDuplicates);
} }
@ -1540,7 +1539,7 @@ public class CollectionUtils {
* @throws IllegalArgumentException if either collection or the comparator is null * @throws IllegalArgumentException if either collection or the comparator is null
* @since 4.0 * @since 4.0
*/ */
public static <O> List<O> collate(final Collection<? extends O> a, final Collection<? extends O> b, public static <O> List<O> collate(final Iterable<? extends O> a, final Iterable<? extends O> b,
final Comparator<? super O> c) { final Comparator<? super O> c) {
return collate(a, b, c, true); return collate(a, b, c, true);
} }
@ -1561,7 +1560,7 @@ public class CollectionUtils {
* @throws IllegalArgumentException if either collection or the comparator is null * @throws IllegalArgumentException if either collection or the comparator is null
* @since 4.0 * @since 4.0
*/ */
public static <O> List<O> collate(final Collection<? extends O> a, final Collection<? extends O> b, public static <O> List<O> collate(final Iterable<? extends O> a, final Iterable<? extends O> b,
final Comparator<? super O> c, final boolean includeDuplicates) { final Comparator<? super O> c, final boolean includeDuplicates) {
if (a == null || b == null) { if (a == null || b == null) {
@ -1571,7 +1570,10 @@ public class CollectionUtils {
throw new IllegalArgumentException("The comparator must not be null"); throw new IllegalArgumentException("The comparator must not be null");
} }
final int totalSize = Math.max(1, a.size() + b.size()); // if both Iterables are a Collection, we can estimate the size
final int totalSize = a instanceof Collection<?> && b instanceof Collection<?> ?
Math.max(1, ((Collection<?>) a).size() + ((Collection<?>) b).size()) : 10;
final Iterator<O> iterator = new CollatingIterator<O>(c, a.iterator(), b.iterator()); final Iterator<O> iterator = new CollatingIterator<O>(c, a.iterator(), b.iterator());
if (includeDuplicates) { if (includeDuplicates) {
return IteratorUtils.toList(iterator, totalSize); return IteratorUtils.toList(iterator, totalSize);