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diff --git a/src/main/java/org/apache/commons/lang3/stream/Streams.java b/src/main/java/org/apache/commons/lang3/stream/Streams.java new file mode 100644 index 000000000..bd5ab630c --- /dev/null +++ b/src/main/java/org/apache/commons/lang3/stream/Streams.java @@ -0,0 +1,816 @@ +/* + * 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.lang3.stream; + +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.Enumeration; +import java.util.Iterator; +import java.util.List; +import java.util.Objects; +import java.util.Set; +import java.util.Spliterator; +import java.util.Spliterators; +import java.util.Spliterators.AbstractSpliterator; +import java.util.function.BiConsumer; +import java.util.function.BinaryOperator; +import java.util.function.Consumer; +import java.util.function.Function; +import java.util.function.Predicate; +import java.util.function.Supplier; +import java.util.stream.Collector; +import java.util.stream.Collectors; +import java.util.stream.Stream; +import java.util.stream.StreamSupport; + +import org.apache.commons.lang3.ArrayUtils; +import org.apache.commons.lang3.function.Failable; +import org.apache.commons.lang3.function.FailableConsumer; +import org.apache.commons.lang3.function.FailableFunction; +import org.apache.commons.lang3.function.FailablePredicate; + +/** + * Provides utility functions, and classes for working with the {@code java.util.stream} package, or more generally, + * with Java 8 lambdas. More specifically, it attempts to address the fact that lambdas are supposed not to throw + * Exceptions, at least not checked Exceptions, AKA instances of {@link Exception}. This enforces the use of constructs + * like: + * + * <pre> + * {@code + * Consumer<java.lang.reflect.Method> consumer = m -> { + * try { + * m.invoke(o, args); + * } catch (Throwable t) { + * throw Failable.rethrow(t); + * } + * }; + * stream.forEach(consumer); + * } + * </pre> + * <p> + * Using a {@link FailableStream}, this can be rewritten as follows: + * </p> + * + * <pre> + * {@code + * Streams.failable(stream).forEach((m) -> m.invoke(o, args)); + * } + * </pre> + * + * Obviously, the second version is much more concise and the spirit of Lambda expressions is met better than in the + * first version. + * + * @see Stream + * @see Failable + * @since 3.11 + */ +public class Streams { + + /** + * A Collector type for arrays. + * + * @param <E> The array type. + */ + public static class ArrayCollector<E> implements Collector<E, List<E>, E[]> { + private static final Set<Characteristics> characteristics = Collections.emptySet(); + private final Class<E> elementType; + + /** + * Constructs a new instance for the given element type. + * + * @param elementType The element type. + */ + public ArrayCollector(final Class<E> elementType) { + this.elementType = Objects.requireNonNull(elementType, "elementType"); + } + + @Override + public BiConsumer<List<E>, E> accumulator() { + return List::add; + } + + @Override + public Set<Characteristics> characteristics() { + return characteristics; + } + + @Override + public BinaryOperator<List<E>> combiner() { + return (left, right) -> { + left.addAll(right); + return left; + }; + } + + @Override + public Function<List<E>, E[]> finisher() { + return list -> list.toArray(ArrayUtils.newInstance(elementType, list.size())); + } + + @Override + public Supplier<List<E>> supplier() { + return ArrayList::new; + } + } + + /** + * Helps implement {@link Streams#of(Enumeration)}. + * + * @param <T> The element type. + */ + private static class EnumerationSpliterator<T> extends AbstractSpliterator<T> { + + private final Enumeration<T> enumeration; + + /** + * Creates a spliterator reporting the given estimated size and additionalCharacteristics. + * + * @param estimatedSize the estimated size of this spliterator if known, otherwise {@code Long.MAX_VALUE}. + * @param additionalCharacteristics properties of this spliterator's source or elements. If {@code SIZED} is reported then this spliterator will + * additionally report {@code SUBSIZED}. + * @param enumeration The Enumeration to wrap. + */ + protected EnumerationSpliterator(final long estimatedSize, final int additionalCharacteristics, final Enumeration<T> enumeration) { + super(estimatedSize, additionalCharacteristics); + this.enumeration = Objects.requireNonNull(enumeration, "enumeration"); + } + + @Override + public void forEachRemaining(final Consumer<? super T> action) { + while (enumeration.hasMoreElements()) { + next(action); + } + } + + private boolean next(final Consumer<? super T> action) { + action.accept(enumeration.nextElement()); + return true; + + } + + @Override + public boolean tryAdvance(final Consumer<? super T> action) { + return enumeration.hasMoreElements() && next(action); + } + } + + /** + * A reduced, and simplified version of a {@link Stream} with failable method signatures. + * + * @param <T> The streams element type. + */ + public static class FailableStream<T> { + + private Stream<T> stream; + private boolean terminated; + + /** + * Constructs a new instance with the given {@code stream}. + * + * @param stream The stream. + */ + public FailableStream(final Stream<T> stream) { + this.stream = stream; + } + + /** + * Returns whether all elements of this stream match the provided predicate. May not evaluate the predicate on all + * elements if not necessary for determining the result. If the stream is empty then {@code true} is returned and the + * predicate is not evaluated. + * + * <p> + * This is a short-circuiting terminal operation. + * </p> + * + * Note This method evaluates the <em>universal quantification</em> of the predicate over the elements of the stream + * (for all x P(x)). If the stream is empty, the quantification is said to be <em>vacuously satisfied</em> and is always + * {@code true} (regardless of P(x)). + * + * @param predicate A non-interfering, stateless predicate to apply to elements of this stream + * @return {@code true} If either all elements of the stream match the provided predicate or the stream is empty, + * otherwise {@code false}. + */ + public boolean allMatch(final FailablePredicate<T, ?> predicate) { + assertNotTerminated(); + return stream().allMatch(Failable.asPredicate(predicate)); + } + + /** + * Returns whether any elements of this stream match the provided predicate. May not evaluate the predicate on all + * elements if not necessary for determining the result. If the stream is empty then {@code false} is returned and the + * predicate is not evaluated. + * + * <p> + * This is a short-circuiting terminal operation. + * </p> + * + * Note This method evaluates the <em>existential quantification</em> of the predicate over the elements of the stream + * (for some x P(x)). + * + * @param predicate A non-interfering, stateless predicate to apply to elements of this stream + * @return {@code true} if any elements of the stream match the provided predicate, otherwise {@code false} + */ + public boolean anyMatch(final FailablePredicate<T, ?> predicate) { + assertNotTerminated(); + return stream().anyMatch(Failable.asPredicate(predicate)); + } + + /** + * Throws IllegalStateException if this stream is already terminated. + * + * @throws IllegalStateException if this stream is already terminated. + */ + protected void assertNotTerminated() { + if (terminated) { + throw new IllegalStateException("This stream is already terminated."); + } + } + + /** + * Performs a mutable reduction operation on the elements of this stream using a {@link Collector}. A {@link Collector} + * encapsulates the functions used as arguments to {@link #collect(Supplier, BiConsumer, BiConsumer)}, allowing for + * reuse of collection strategies and composition of collect operations such as multiple-level grouping or partitioning. + * + * <p> + * If the underlying stream is parallel, and the {@link Collector} is concurrent, and either the stream is unordered or + * the collector is unordered, then a concurrent reduction will be performed (see {@link Collector} for details on + * concurrent reduction.) + * </p> + * + * <p> + * This is a terminal operation. + * </p> + * + * <p> + * When executed in parallel, multiple intermediate results may be instantiated, populated, and merged so as to maintain + * isolation of mutable data structures. Therefore, even when executed in parallel with non-thread-safe data structures + * (such as {@link ArrayList}), no additional synchronization is needed for a parallel reduction. + * </p> + * + * Note The following will accumulate strings into an ArrayList: + * + * <pre> + * {@code + * List<String> asList = stringStream.collect(Collectors.toList()); + * } + * </pre> + * + * <p> + * The following will classify {@code Person} objects by city: + * </p> + * + * <pre> + * {@code + * Map<String, List<Person>> peopleByCity = personStream.collect(Collectors.groupingBy(Person::getCity)); + * } + * </pre> + * + * <p> + * The following will classify {@code Person} objects by state and city, cascading two {@link Collector}s together: + * </p> + * + * <pre> + * {@code + * Map<String, Map<String, List<Person>>> peopleByStateAndCity = personStream + * .collect(Collectors.groupingBy(Person::getState, Collectors.groupingBy(Person::getCity))); + * } + * </pre> + * + * @param <R> the type of the result + * @param <A> the intermediate accumulation type of the {@link Collector} + * @param collector the {@link Collector} describing the reduction + * @return the result of the reduction + * @see #collect(Supplier, BiConsumer, BiConsumer) + * @see Collectors + */ + public <A, R> R collect(final Collector<? super T, A, R> collector) { + makeTerminated(); + return stream().collect(collector); + } + + /** + * Performs a mutable reduction operation on the elements of this FailableStream. A mutable reduction is one in which + * the reduced value is a mutable result container, such as an {@link ArrayList}, and elements are incorporated by + * updating the state of the result rather than by replacing the result. This produces a result equivalent to: + * + * <pre> + * {@code + * R result = supplier.get(); + * for (T element : this stream) + * accumulator.accept(result, element); + * return result; + * } + * </pre> + * + * <p> + * Like {@link #reduce(Object, BinaryOperator)}, {@code collect} operations can be parallelized without requiring + * additional synchronization. + * </p> + * + * <p> + * This is a terminal operation. + * </p> + * + * Note There are many existing classes in the JDK whose signatures are well-suited for use with method references as + * arguments to {@code collect()}. For example, the following will accumulate strings into an {@link ArrayList}: + * + * <pre> + * {@code + * List<String> asList = stringStream.collect(ArrayList::new, ArrayList::add, ArrayList::addAll); + * } + * </pre> + * + * <p> + * The following will take a stream of strings and concatenates them into a single string: + * </p> + * + * <pre> + * {@code + * String concat = stringStream.collect(StringBuilder::new, StringBuilder::append, StringBuilder::append).toString(); + * } + * </pre> + * + * @param <R> type of the result + * @param <A> Type of the accumulator. + * @param supplier a function that creates a new result container. For a parallel execution, this function may be called + * multiple times and must return a fresh value each time. + * @param accumulator An associative, non-interfering, stateless function for incorporating an additional element into a + * result + * @param combiner An associative, non-interfering, stateless function for combining two values, which must be + * compatible with the accumulator function + * @return The result of the reduction + */ + public <A, R> R collect(final Supplier<R> supplier, final BiConsumer<R, ? super T> accumulator, final BiConsumer<R, R> combiner) { + makeTerminated(); + return stream().collect(supplier, accumulator, combiner); + } + + /** + * Returns a FailableStream consisting of the elements of this stream that match the given FailablePredicate. + * + * <p> + * This is an intermediate operation. + * </p> + * + * @param predicate a non-interfering, stateless predicate to apply to each element to determine if it should be + * included. + * @return the new stream + */ + public FailableStream<T> filter(final FailablePredicate<T, ?> predicate) { + assertNotTerminated(); + stream = stream.filter(Failable.asPredicate(predicate)); + return this; + } + + /** + * Performs an action for each element of this stream. + * + * <p> + * This is a terminal operation. + * </p> + * + * <p> + * The behavior of this operation is explicitly nondeterministic. For parallel stream pipelines, this operation does + * <em>not</em> guarantee to respect the encounter order of the stream, as doing so would sacrifice the benefit of + * parallelism. For any given element, the action may be performed at whatever time and in whatever thread the library + * chooses. If the action accesses shared state, it is responsible for providing the required synchronization. + * </p> + * + * @param action a non-interfering action to perform on the elements + */ + public void forEach(final FailableConsumer<T, ?> action) { + makeTerminated(); + stream().forEach(Failable.asConsumer(action)); + } + + /** + * Marks this stream as terminated. + * + * @throws IllegalStateException if this stream is already terminated. + */ + protected void makeTerminated() { + assertNotTerminated(); + terminated = true; + } + + /** + * Returns a stream consisting of the results of applying the given function to the elements of this stream. + * + * <p> + * This is an intermediate operation. + * </p> + * + * @param <R> The element type of the new stream + * @param mapper A non-interfering, stateless function to apply to each element + * @return the new stream + */ + public <R> FailableStream<R> map(final FailableFunction<T, R, ?> mapper) { + assertNotTerminated(); + return new FailableStream<>(stream.map(Failable.asFunction(mapper))); + } + + /** + * Performs a reduction on the elements of this stream, using the provided identity value and an associative + * accumulation function, and returns the reduced value. This is equivalent to: + * + * <pre> + * {@code + * T result = identity; + * for (T element : this stream) + * result = accumulator.apply(result, element) + * return result; + * } + * </pre> + * + * but is not constrained to execute sequentially. + * + * <p> + * The {@code identity} value must be an identity for the accumulator function. This means that for all {@code t}, + * {@code accumulator.apply(identity, t)} is equal to {@code t}. The {@code accumulator} function must be an associative + * function. + * </p> + * + * <p> + * This is a terminal operation. + * </p> + * + * Note Sum, min, max, average, and string concatenation are all special cases of reduction. Summing a stream of numbers + * can be expressed as: + * + * <pre> + * {@code + * Integer sum = integers.reduce(0, (a, b) -> a + b); + * } + * </pre> + * + * or: + * + * <pre> + * {@code + * Integer sum = integers.reduce(0, Integer::sum); + * } + * </pre> + * + * <p> + * While this may seem a more roundabout way to perform an aggregation compared to simply mutating a running total in a + * loop, reduction operations parallelize more gracefully, without needing additional synchronization and with greatly + * reduced risk of data races. + * </p> + * + * @param identity the identity value for the accumulating function + * @param accumulator an associative, non-interfering, stateless function for combining two values + * @return the result of the reduction + */ + public T reduce(final T identity, final BinaryOperator<T> accumulator) { + makeTerminated(); + return stream().reduce(identity, accumulator); + } + + /** + * Converts the FailableStream into an equivalent stream. + * + * @return A stream, which will return the same elements, which this FailableStream would return. + */ + public Stream<T> stream() { + return stream; + } + } + + /** + * Converts the given {@link Collection} into a {@link FailableStream}. This is basically a simplified, reduced version + * of the {@link Stream} class, with the same underlying element stream, except that failable objects, like + * {@link FailablePredicate}, {@link FailableFunction}, or {@link FailableConsumer} may be applied, instead of + * {@link Predicate}, {@link Function}, or {@link Consumer}. The idea is to rewrite a code snippet like this: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final Function<O, String> mapper = (o) -> { + * try { + * return (String) m.invoke(o); + * } catch (Throwable t) { + * throw Failable.rethrow(t); + * } + * }; + * final List<String> strList = list.stream().map(mapper).collect(Collectors.toList()); + * } + * </pre> + * + * as follows: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final List<String> strList = Failable.stream(list.stream()).map((o) -> (String) m.invoke(o)).collect(Collectors.toList()); + * } + * </pre> + * + * While the second version may not be <em>quite</em> as efficient (because it depends on the creation of additional, + * intermediate objects, of type FailableStream), it is much more concise, and readable, and meets the spirit of Lambdas + * better than the first version. + * + * @param <T> The streams element type. + * @param stream The stream, which is being converted. + * @return The {@link FailableStream}, which has been created by converting the stream. + * @since 3.13.0 + */ + public static <T> FailableStream<T> failableStream(final Collection<T> stream) { + return failableStream(of(stream)); + } + + /** + * Converts the given {@link Stream stream} into a {@link FailableStream}. This is basically a simplified, reduced + * version of the {@link Stream} class, with the same underlying element stream, except that failable objects, like + * {@link FailablePredicate}, {@link FailableFunction}, or {@link FailableConsumer} may be applied, instead of + * {@link Predicate}, {@link Function}, or {@link Consumer}. The idea is to rewrite a code snippet like this: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final Function<O, String> mapper = (o) -> { + * try { + * return (String) m.invoke(o); + * } catch (Throwable t) { + * throw Failable.rethrow(t); + * } + * }; + * final List<String> strList = list.stream().map(mapper).collect(Collectors.toList()); + * } + * </pre> + * + * as follows: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final List<String> strList = Failable.stream(list.stream()).map((o) -> (String) m.invoke(o)).collect(Collectors.toList()); + * } + * </pre> + * + * While the second version may not be <em>quite</em> as efficient (because it depends on the creation of additional, + * intermediate objects, of type FailableStream), it is much more concise, and readable, and meets the spirit of Lambdas + * better than the first version. + * + * @param <T> The streams element type. + * @param stream The stream, which is being converted. + * @return The {@link FailableStream}, which has been created by converting the stream. + * @since 3.13.0 + */ + public static <T> FailableStream<T> failableStream(final Stream<T> stream) { + return new FailableStream<>(stream); + } + + /** + * Streams only instances of the give Class in a collection. + * <p> + * This method shorthand for: + * </p> + * <pre> + * {@code (Stream<E>) Streams.toStream(collection).filter(collection, SomeClass.class::isInstance);} + * </pre> + * + * @param <E> the type of elements in the collection we want to stream. + * @param clazz the type of elements in the collection we want to stream. + * @param collection the collection to stream or null. + * @return A non-null stream that only provides instances we want. + * @since 3.13.0 + */ + public static <E> Stream<E> instancesOf(final Class<? super E> clazz, final Collection<? super E> collection) { + return instancesOf(clazz, of(collection)); + } + + @SuppressWarnings("unchecked") // After the isInstance check, we still need to type-cast. + private static <E> Stream<E> instancesOf(final Class<? super E> clazz, final Stream<?> stream) { + return (Stream<E>) of(stream).filter(clazz::isInstance); + } + + /** + * Streams the non-null elements of a collection. + * + * @param <E> the type of elements in the collection. + * @param collection the collection to stream or null. + * @return A non-null stream that filters out null elements. + * @since 3.13.0 + */ + public static <E> Stream<E> nonNull(final Collection<E> collection) { + return of(collection).filter(Objects::nonNull); + } + + /** + * Streams the non-null elements of an array. + * + * @param <E> the type of elements in the collection. + * @param array the array to stream or null. + * @return A non-null stream that filters out null elements. + * @since 3.13.0 + */ + @SafeVarargs + public static <E> Stream<E> nonNull(final E... array) { + return nonNull(of(array)); + } + + /** + * Streams the non-null elements of a stream. + * + * @param <E> the type of elements in the collection. + * @param stream the stream to stream or null. + * @return A non-null stream that filters out null elements. + * @since 3.13.0 + */ + public static <E> Stream<E> nonNull(final Stream<E> stream) { + return of(stream).filter(Objects::nonNull); + } + + /** + * Delegates to {@link Collection#stream()} or returns {@link Stream#empty()} if the collection is null. + * + * @param <E> the type of elements in the collection. + * @param collection the collection to stream or null. + * @return {@link Collection#stream()} or {@link Stream#empty()} if the collection is null. + * @since 3.13.0 + */ + public static <E> Stream<E> of(final Collection<E> collection) { + return collection == null ? Stream.empty() : collection.stream(); + } + + /** + * Streams the elements of the given enumeration in order. + * + * @param <E> The enumeration element type. + * @param enumeration The enumeration to stream. + * @return a new stream. + * @since 3.13.0 + */ + public static <E> Stream<E> of(final Enumeration<E> enumeration) { + return StreamSupport.stream(new EnumerationSpliterator<>(Long.MAX_VALUE, Spliterator.ORDERED, enumeration), false); + } + + /** + * Creates a stream on the given Iterable. + * + * @param <E> the type of elements in the Iterable. + * @param iterable the Iterable to stream or null. + * @return a new Stream or {@link Stream#empty()} if the Iterable is null. + * @since 3.13.0 + */ + public static <E> Stream<E> of(final Iterable<E> iterable) { + return iterable == null ? Stream.empty() : StreamSupport.stream(iterable.spliterator(), false); + } + + /** + * Creates a stream on the given Iterator. + * + * @param <E> the type of elements in the Iterator. + * @param iterator the Iterator to stream or null. + * @return a new Stream or {@link Stream#empty()} if the Iterator is null. + * @since 3.13.0 + */ + public static <E> Stream<E> of(final Iterator<E> iterator) { + return iterator == null ? Stream.empty() : StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false); + } + + /** + * Returns the stream or {@link Stream#empty()} if the stream is null. + * + * @param <E> the type of elements in the collection. + * @param stream the stream to stream or null. + * @return the stream or {@link Stream#empty()} if the stream is null. + * @since 3.13.0 + */ + private static <E> Stream<E> of(final Stream<E> stream) { + return stream == null ? Stream.empty() : stream; + } + + /** + * Null-safe version of {@link Stream#of(Object[])}. + * + * @param <T> the type of stream elements. + * @param values the elements of the new stream, may be {@code null}. + * @return the new stream on {@code values} or {@link Stream#empty()}. + * @since 3.13.0 + */ + @SafeVarargs // Creating a stream from an array is safe + public static <T> Stream<T> of(final T... values) { + return values == null ? Stream.empty() : Stream.of(values); + } + + /** + * Converts the given {@link Collection} into a {@link FailableStream}. This is basically a simplified, reduced version + * of the {@link Stream} class, with the same underlying element stream, except that failable objects, like + * {@link FailablePredicate}, {@link FailableFunction}, or {@link FailableConsumer} may be applied, instead of + * {@link Predicate}, {@link Function}, or {@link Consumer}. The idea is to rewrite a code snippet like this: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final Function<O, String> mapper = (o) -> { + * try { + * return (String) m.invoke(o); + * } catch (Throwable t) { + * throw Failable.rethrow(t); + * } + * }; + * final List<String> strList = list.stream().map(mapper).collect(Collectors.toList()); + * } + * </pre> + * + * as follows: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final List<String> strList = Failable.stream(list.stream()).map((o) -> (String) m.invoke(o)).collect(Collectors.toList()); + * } + * </pre> + * + * While the second version may not be <em>quite</em> as efficient (because it depends on the creation of additional, + * intermediate objects, of type FailableStream), it is much more concise, and readable, and meets the spirit of Lambdas + * better than the first version. + * + * @param <E> The streams element type. + * @param collection The stream, which is being converted. + * @return The {@link FailableStream}, which has been created by converting the stream. + * @deprecated Use {@link #failableStream(Collection)}. + */ + @Deprecated + public static <E> FailableStream<E> stream(final Collection<E> collection) { + return failableStream(collection); + } + + /** + * Converts the given {@link Stream stream} into a {@link FailableStream}. This is basically a simplified, reduced + * version of the {@link Stream} class, with the same underlying element stream, except that failable objects, like + * {@link FailablePredicate}, {@link FailableFunction}, or {@link FailableConsumer} may be applied, instead of + * {@link Predicate}, {@link Function}, or {@link Consumer}. The idea is to rewrite a code snippet like this: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final Function<O, String> mapper = (o) -> { + * try { + * return (String) m.invoke(o); + * } catch (Throwable t) { + * throw Failable.rethrow(t); + * } + * }; + * final List<String> strList = list.stream().map(mapper).collect(Collectors.toList()); + * } + * </pre> + * + * as follows: + * + * <pre> + * {@code + * final List<O> list; + * final Method m; + * final List<String> strList = Failable.stream(list.stream()).map((o) -> (String) m.invoke(o)).collect(Collectors.toList()); + * } + * </pre> + * + * While the second version may not be <em>quite</em> as efficient (because it depends on the creation of additional, + * intermediate objects, of type FailableStream), it is much more concise, and readable, and meets the spirit of Lambdas + * better than the first version. + * + * @param <T> The streams element type. + * @param stream The stream, which is being converted. + * @return The {@link FailableStream}, which has been created by converting the stream. + * @deprecated Use {@link #failableStream(Stream)}. + */ + @Deprecated + public static <T> FailableStream<T> stream(final Stream<T> stream) { + return failableStream(stream); + } + + /** + * Returns a {@link Collector} that accumulates the input elements into a new array. + * + * @param pElementType Type of an element in the array. + * @param <T> the type of the input elements + * @return a {@link Collector} which collects all the input elements into an array, in encounter order + */ + public static <T> Collector<T, ?, T[]> toArray(final Class<T> pElementType) { + return new ArrayCollector<>(pElementType); + } +} |