Fixing Checkstyle problems.
This commit is contained in:
Jochen Wiedmann
parent
2ea44b2ada
commit
3ce3b27dbd
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@ -16,6 +16,7 @@
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*/
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package org.apache.commons.lang3;
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import java.util.Collection;
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import java.util.function.BiConsumer;
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import java.util.function.BinaryOperator;
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import java.util.function.Consumer;
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@ -48,7 +49,7 @@ import org.apache.commons.lang3.Functions.FailablePredicate;
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* </pre>
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* Using a {@link FailableStream}, this can be rewritten as follows:
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* <pre>
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* ObjectStreams.failable(stream).forEach((m) -> m.invoke(o, args));
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* Streams.failable(stream).forEach((m) -> m.invoke(o, args));
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* </pre>
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* Obviously, the second version is much more concise and the spirit of
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* Lambda expressions is met better than in the first version.
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@ -56,309 +57,309 @@ import org.apache.commons.lang3.Functions.FailablePredicate;
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* @see Functions
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*/
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public class Streams {
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/** A reduced, and simplified version of a {@link Stream} with
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* failable method signatures.
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* @param <O> The streams element type.
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*/
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public static class FailableStream<O extends Object> {
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private Stream<O> stream;
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private boolean terminated;
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/** A reduced, and simplified version of a {@link Stream} with
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* failable method signatures.
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* @param <O> The streams element type.
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*/
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public static class FailableStream<O extends Object> {
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private Stream<O> stream;
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private boolean terminated;
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public FailableStream(Stream<O> pStream) {
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stream = pStream;
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}
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public FailableStream(Stream<O> pStream) {
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stream = pStream;
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}
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protected void assertNotTerminated() {
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if (terminated) {
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throw new IllegalStateException("This stream is already terminated.");
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}
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}
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protected void assertNotTerminated() {
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if (terminated) {
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throw new IllegalStateException("This stream is already terminated.");
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}
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}
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protected void makeTerminated() {
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assertNotTerminated();
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terminated = true;
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}
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protected void makeTerminated() {
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assertNotTerminated();
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terminated = true;
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}
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/**
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* Returns a FailableStream consisting of the elements of this stream that match
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* the given FailablePredicate.
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*
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* <p>This is an intermediate operation.
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*
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* @param pPredicate a non-interfering, stateless predicate to apply to each
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* element to determine if it should be included.
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* @return the new stream
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*/
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public FailableStream<O> filter(FailablePredicate<O,?> pPredicate){
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assertNotTerminated();
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stream = stream.filter(Functions.asPredicate(pPredicate));
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return this;
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}
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/**
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* Returns a FailableStream consisting of the elements of this stream that match
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* the given FailablePredicate.
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*
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* <p>This is an intermediate operation.
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*
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* @param pPredicate a non-interfering, stateless predicate to apply to each
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* element to determine if it should be included.
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* @return the new stream
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*/
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public FailableStream<O> filter(FailablePredicate<O, ?> pPredicate){
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assertNotTerminated();
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stream = stream.filter(Functions.asPredicate(pPredicate));
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return this;
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}
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/**
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* Performs an action for each element of this stream.
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*
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* <p>This is a terminal operation.
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*
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* <p>The behavior of this operation is explicitly nondeterministic.
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* For parallel stream pipelines, this operation does <em>not</em>
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* guarantee to respect the encounter order of the stream, as doing so
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* would sacrifice the benefit of parallelism. For any given element, the
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* action may be performed at whatever time and in whatever thread the
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* library chooses. If the action accesses shared state, it is
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* responsible for providing the required synchronization.
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*
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* @param pAction a non-interfering action to perform on the elements
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*/
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public void forEach(FailableConsumer<O,?> pAction) {
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makeTerminated();
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stream().forEach(Functions.asConsumer(pAction));
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}
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/**
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* Performs a mutable reduction operation on the elements of this stream using a
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* {@code Collector}. A {@code Collector}
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* encapsulates the functions used as arguments to
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* {@link #collect(Supplier, BiConsumer, BiConsumer)}, allowing for reuse of
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* collection strategies and composition of collect operations such as
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* multiple-level grouping or partitioning.
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*
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* <p>If the underlying stream is parallel, and the {@code Collector}
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* is concurrent, and either the stream is unordered or the collector is
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* unordered, then a concurrent reduction will be performed
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* (see {@link Collector} for details on concurrent reduction.)
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*
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* <p>This is a terminal operation.
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*
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* <p>When executed in parallel, multiple intermediate results may be
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* instantiated, populated, and merged so as to maintain isolation of
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* mutable data structures. Therefore, even when executed in parallel
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* with non-thread-safe data structures (such as {@code ArrayList}), no
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* additional synchronization is needed for a parallel reduction.
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*
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* \@apiNote
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* The following will accumulate strings into an ArrayList:
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* <pre>{@code
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* List<String> asList = stringStream.collect(Collectors.toList());
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* }</pre>
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*
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* <p>The following will classify {@code Person} objects by city:
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* <pre>{@code
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* Map<String, List<Person>> peopleByCity
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* = personStream.collect(Collectors.groupingBy(Person::getCity));
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* }</pre>
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*
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* <p>The following will classify {@code Person} objects by state and city,
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* cascading two {@code Collector}s together:
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* <pre>{@code
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* Map<String, Map<String, List<Person>>> peopleByStateAndCity
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* = personStream.collect(Collectors.groupingBy(Person::getState,
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* Collectors.groupingBy(Person::getCity)));
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* }</pre>
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*
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* @param <R> the type of the result
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* @param <A> the intermediate accumulation type of the {@code Collector}
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* @param pCollector the {@code Collector} describing the reduction
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* @return the result of the reduction
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* @see #collect(Supplier, BiConsumer, BiConsumer)
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* @see Collectors
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*/
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public <A,R> R collect(Collector<? super O,A,R> pCollector) {
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/**
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* Performs an action for each element of this stream.
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*
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* <p>This is a terminal operation.
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*
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* <p>The behavior of this operation is explicitly nondeterministic.
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* For parallel stream pipelines, this operation does <em>not</em>
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* guarantee to respect the encounter order of the stream, as doing so
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* would sacrifice the benefit of parallelism. For any given element, the
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* action may be performed at whatever time and in whatever thread the
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* library chooses. If the action accesses shared state, it is
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* responsible for providing the required synchronization.
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*
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* @param pAction a non-interfering action to perform on the elements
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*/
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public void forEach(FailableConsumer<O, ?> pAction) {
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makeTerminated();
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return stream().collect(pCollector);
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}
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stream().forEach(Functions.asConsumer(pAction));
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}
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/**
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* Performs a mutable reduction operation on the elements of this FailableStream.
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* A mutable reduction is one in which the reduced value is a mutable result
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* container, such as an {@code ArrayList}, and elements are incorporated by updating
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* the state of the result rather than by replacing the result. This produces a result equivalent to:
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* <pre>{@code
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* R result = supplier.get();
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* for (T element : this stream)
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* accumulator.accept(result, element);
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* return result;
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* }</pre>
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*
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* <p>Like {@link #reduce(Object, BinaryOperator)}, {@code collect} operations
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* can be parallelized without requiring additional synchronization.
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*
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* <p>This is a terminal operation.
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*
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* \@apiNote There are many existing classes in the JDK whose signatures are
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* well-suited for use with method references as arguments to {@code collect()}.
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* For example, the following will accumulate strings into an {@code ArrayList}:
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* <pre>{@code
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* List<String> asList = stringStream.collect(ArrayList::new, ArrayList::add,
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* ArrayList::addAll);
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* }</pre>
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*
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* <p>The following will take a stream of strings and concatenates them into a
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* single string:
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* <pre>{@code
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* String concat = stringStream.collect(StringBuilder::new, StringBuilder::append,
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* StringBuilder::append)
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* .toString();
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* }</pre>
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*
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* @param <R> type of the result
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* @param <A> Type of the accumulator.
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* @param pSupplier a function that creates a new result container. For a
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* parallel execution, this function may be called
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* multiple times and must return a fresh value each time.
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* @param pAccumulator An associative, non-interfering, stateless function for
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* incorporating an additional element into a result
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* @param pCombiner An associative, non-interfering, stateless
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* function for combining two values, which must be compatible with the
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* accumulator function
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* @return The result of the reduction
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*/
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public <A,R> R collect(Supplier<R> pSupplier, BiConsumer<R,? super O> pAccumulator, BiConsumer<R,R> pCombiner) {
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/**
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* Performs a mutable reduction operation on the elements of this stream using a
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* {@code Collector}. A {@code Collector}
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* encapsulates the functions used as arguments to
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* {@link #collect(Supplier, BiConsumer, BiConsumer)}, allowing for reuse of
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* collection strategies and composition of collect operations such as
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* multiple-level grouping or partitioning.
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*
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* <p>If the underlying stream is parallel, and the {@code Collector}
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* is concurrent, and either the stream is unordered or the collector is
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* unordered, then a concurrent reduction will be performed
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* (see {@link Collector} for details on concurrent reduction.)
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*
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* <p>This is a terminal operation.
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*
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* <p>When executed in parallel, multiple intermediate results may be
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* instantiated, populated, and merged so as to maintain isolation of
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* mutable data structures. Therefore, even when executed in parallel
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* with non-thread-safe data structures (such as {@code ArrayList}), no
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* additional synchronization is needed for a parallel reduction.
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*
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* \@apiNote
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* The following will accumulate strings into an ArrayList:
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* <pre>{@code
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* List<String> asList = stringStream.collect(Collectors.toList());
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* }</pre>
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*
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* <p>The following will classify {@code Person} objects by city:
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* <pre>{@code
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* Map<String, List<Person>> peopleByCity
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* = personStream.collect(Collectors.groupingBy(Person::getCity));
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* }</pre>
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*
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* <p>The following will classify {@code Person} objects by state and city,
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* cascading two {@code Collector}s together:
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* <pre>{@code
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* Map<String, Map<String, List<Person>>> peopleByStateAndCity
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* = personStream.collect(Collectors.groupingBy(Person::getState,
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* Collectors.groupingBy(Person::getCity)));
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* }</pre>
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*
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* @param <R> the type of the result
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* @param <A> the intermediate accumulation type of the {@code Collector}
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* @param pCollector the {@code Collector} describing the reduction
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* @return the result of the reduction
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* @see #collect(Supplier, BiConsumer, BiConsumer)
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* @see Collectors
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*/
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public <A, R> R collect(Collector<? super O, A, R> pCollector) {
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makeTerminated();
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return stream().collect(pSupplier, pAccumulator, pCombiner);
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}
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return stream().collect(pCollector);
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}
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/**
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* Performs a reduction on the elements of this stream, using the provided
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* identity value and an associative accumulation function, and returns
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* the reduced value. This is equivalent to:
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* <pre>{@code
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* T result = identity;
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* for (T element : this stream)
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* result = accumulator.apply(result, element)
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* return result;
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* }</pre>
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*
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* but is not constrained to execute sequentially.
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*
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* <p>The {@code identity} value must be an identity for the accumulator
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* function. This means that for all {@code t},
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* {@code accumulator.apply(identity, t)} is equal to {@code t}.
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* The {@code accumulator} function must be an associative function.
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*
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* <p>This is a terminal operation.
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*
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* \@apiNote Sum, min, max, average, and string concatenation are all special
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* cases of reduction. Summing a stream of numbers can be expressed as:
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*
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* <pre>{@code
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* Integer sum = integers.reduce(0, (a, b) -> a+b);
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* }</pre>
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*
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* or:
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*
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* <pre>{@code
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* Integer sum = integers.reduce(0, Integer::sum);
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* }</pre>
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*
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* <p>While this may seem a more roundabout way to perform an aggregation
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* compared to simply mutating a running total in a loop, reduction
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* operations parallelize more gracefully, without needing additional
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* synchronization and with greatly reduced risk of data races.
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*
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* @param pIdentity the identity value for the accumulating function
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* @param pAccumulator an associative, non-interfering, stateless
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* function for combining two values
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* @return the result of the reduction
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*/
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public O reduce(O pIdentity, BinaryOperator<O> pAccumulator) {
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/**
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* Performs a mutable reduction operation on the elements of this FailableStream.
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* A mutable reduction is one in which the reduced value is a mutable result
|
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* container, such as an {@code ArrayList}, and elements are incorporated by updating
|
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* the state of the result rather than by replacing the result. This produces a result equivalent to:
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* <pre>{@code
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* R result = supplier.get();
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* for (T element : this stream)
|
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* accumulator.accept(result, element);
|
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* return result;
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* }</pre>
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*
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* <p>Like {@link #reduce(Object, BinaryOperator)}, {@code collect} operations
|
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* can be parallelized without requiring additional synchronization.
|
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*
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* <p>This is a terminal operation.
|
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*
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* \@apiNote There are many existing classes in the JDK whose signatures are
|
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* well-suited for use with method references as arguments to {@code collect()}.
|
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* For example, the following will accumulate strings into an {@code ArrayList}:
|
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* <pre>{@code
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* List<String> asList = stringStream.collect(ArrayList::new, ArrayList::add,
|
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* ArrayList::addAll);
|
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* }</pre>
|
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*
|
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* <p>The following will take a stream of strings and concatenates them into a
|
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* single string:
|
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* <pre>{@code
|
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* String concat = stringStream.collect(StringBuilder::new, StringBuilder::append,
|
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* StringBuilder::append)
|
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* .toString();
|
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* }</pre>
|
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*
|
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* @param <R> type of the result
|
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* @param <A> Type of the accumulator.
|
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* @param pSupplier a function that creates a new result container. For a
|
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* parallel execution, this function may be called
|
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* multiple times and must return a fresh value each time.
|
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* @param pAccumulator An associative, non-interfering, stateless function for
|
||||
* incorporating an additional element into a result
|
||||
* @param pCombiner An associative, non-interfering, stateless
|
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* function for combining two values, which must be compatible with the
|
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* accumulator function
|
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* @return The result of the reduction
|
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*/
|
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public <A, R> R collect(Supplier<R> pSupplier, BiConsumer<R, ? super O> pAccumulator, BiConsumer<R, R> pCombiner) {
|
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makeTerminated();
|
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return stream().reduce(pIdentity, pAccumulator);
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}
|
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return stream().collect(pSupplier, pAccumulator, pCombiner);
|
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}
|
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|
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/**
|
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* Returns a stream consisting of the results of applying the given
|
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* function to the elements of this stream.
|
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*
|
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* <p>This is an intermediate operation.
|
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*
|
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* @param <R> The element type of the new stream
|
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* @param pMapper A non-interfering, stateless function to apply to each element
|
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* @return the new stream
|
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*/
|
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public <R> FailableStream<R> map(FailableFunction<O,R,?> pMapper) {
|
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assertNotTerminated();
|
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return new FailableStream<R>(stream.map(Functions.asFunction(pMapper)));
|
||||
}
|
||||
/**
|
||||
* 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:
|
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* <pre>{@code
|
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* T result = identity;
|
||||
* for (T element : this stream)
|
||||
* result = accumulator.apply(result, element)
|
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* return result;
|
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* }</pre>
|
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*
|
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* but is not constrained to execute sequentially.
|
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*
|
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* <p>The {@code identity} value must be an identity for the accumulator
|
||||
* function. This means that for all {@code t},
|
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* {@code accumulator.apply(identity, t)} is equal to {@code t}.
|
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* The {@code accumulator} function must be an associative function.
|
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*
|
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* <p>This is a terminal operation.
|
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*
|
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* \@apiNote Sum, min, max, average, and string concatenation are all special
|
||||
* cases of reduction. Summing a stream of numbers can be expressed as:
|
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*
|
||||
* <pre>{@code
|
||||
* Integer sum = integers.reduce(0, (a, b) -> a+b);
|
||||
* }</pre>
|
||||
*
|
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* or:
|
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*
|
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* <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.
|
||||
*
|
||||
* @param pIdentity the identity value for the accumulating function
|
||||
* @param pAccumulator an associative, non-interfering, stateless
|
||||
* function for combining two values
|
||||
* @return the result of the reduction
|
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*/
|
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public O reduce(O pIdentity, BinaryOperator<O> pAccumulator) {
|
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makeTerminated();
|
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return stream().reduce(pIdentity, pAccumulator);
|
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}
|
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|
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/**
|
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* Converts the FailableStream into an equivalent stream.
|
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* @return A stream, which will return the same elements, which this FailableStream would return.
|
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*/
|
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public Stream<O> stream() {
|
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return stream;
|
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}
|
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/**
|
||||
* Returns a stream consisting of the results of applying the given
|
||||
* function to the elements of this stream.
|
||||
*
|
||||
* <p>This is an intermediate operation.
|
||||
*
|
||||
* @param <R> The element type of the new stream
|
||||
* @param pMapper A non-interfering, stateless function to apply to each element
|
||||
* @return the new stream
|
||||
*/
|
||||
public <R> FailableStream<R> map(FailableFunction<O, R, ?> pMapper) {
|
||||
assertNotTerminated();
|
||||
return new FailableStream<R>(stream.map(Functions.asFunction(pMapper)));
|
||||
}
|
||||
|
||||
/**
|
||||
* 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.
|
||||
*
|
||||
* \@apiNote
|
||||
* 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 pPredicate 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(FailablePredicate<O,?> pPredicate) {
|
||||
assertNotTerminated();
|
||||
return stream().allMatch(Functions.asPredicate(pPredicate));
|
||||
}
|
||||
/**
|
||||
* Converts the FailableStream into an equivalent stream.
|
||||
* @return A stream, which will return the same elements, which this FailableStream would return.
|
||||
*/
|
||||
public Stream<O> stream() {
|
||||
return stream;
|
||||
}
|
||||
|
||||
/**
|
||||
* 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.
|
||||
*
|
||||
* \@apiNote
|
||||
* This method evaluates the <em>existential quantification</em> of the
|
||||
* predicate over the elements of the stream (for some x P(x)).
|
||||
*
|
||||
* @param pPredicate 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(FailablePredicate<O,?> pPredicate) {
|
||||
/**
|
||||
* 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.
|
||||
*
|
||||
* \@apiNote
|
||||
* 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 pPredicate 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(FailablePredicate<O, ?> pPredicate) {
|
||||
assertNotTerminated();
|
||||
return stream().allMatch(Functions.asPredicate(pPredicate));
|
||||
}
|
||||
|
||||
/**
|
||||
* 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.
|
||||
*
|
||||
* \@apiNote
|
||||
* This method evaluates the <em>existential quantification</em> of the
|
||||
* predicate over the elements of the stream (for some x P(x)).
|
||||
*
|
||||
* @param pPredicate 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(FailablePredicate<O, ?> pPredicate) {
|
||||
assertNotTerminated();
|
||||
return stream().anyMatch(Functions.asPredicate(pPredicate));
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* 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>
|
||||
* final List<O> list;
|
||||
* final Method m;
|
||||
* final Function<O,String> mapper = (o) -> {
|
||||
* try {
|
||||
* return (String) m.invoke(o);
|
||||
* } catch (Throwable t) {
|
||||
* throw Functions.rethrow(t);
|
||||
* }
|
||||
* };
|
||||
* final List<String> strList = list.stream()
|
||||
* .map(mapper).collect(Collectors.toList());
|
||||
* </pre>
|
||||
* as follows:
|
||||
* <pre>
|
||||
/**
|
||||
* 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>
|
||||
* final List<O> list;
|
||||
* final Method m;
|
||||
* final Function<O,String> mapper = (o) -> {
|
||||
* try {
|
||||
* return (String) m.invoke(o);
|
||||
* } catch (Throwable t) {
|
||||
* throw Functions.rethrow(t);
|
||||
* }
|
||||
* };
|
||||
* final List<String> strList = list.stream()
|
||||
* .map(mapper).collect(Collectors.toList());
|
||||
* </pre>
|
||||
* as follows:
|
||||
* <pre>
|
||||
* final List<O> list;
|
||||
* final Method m;
|
||||
* final List<String> strList = Functions.stream(list.stream())
|
||||
|
|
@ -369,12 +370,54 @@ public class Streams {
|
|||
* intermediate objects, of type FailableStream), it is much more
|
||||
* concise, and readable, and meets the spirit of Lambdas better
|
||||
* than the first version.
|
||||
* @param <O> The streams element type.
|
||||
* @param pStream The stream, which is being converted.
|
||||
* @return The {@link FailableStream}, which has been created by
|
||||
* converting the stream.
|
||||
*/
|
||||
public static <O> FailableStream<O> stream(Stream<O> pStream) {
|
||||
return new FailableStream<O>(pStream);
|
||||
}
|
||||
* @param <O> The streams element type.
|
||||
* @param pStream The stream, which is being converted.
|
||||
* @return The {@link FailableStream}, which has been created by
|
||||
* converting the stream.
|
||||
*/
|
||||
public static <O> FailableStream<O> stream(Stream<O> pStream) {
|
||||
return new FailableStream<O>(pStream);
|
||||
}
|
||||
|
||||
/**
|
||||
* 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>
|
||||
* final List<O> list;
|
||||
* final Method m;
|
||||
* final Function<O,String> mapper = (o) -> {
|
||||
* try {
|
||||
* return (String) m.invoke(o);
|
||||
* } catch (Throwable t) {
|
||||
* throw Functions.rethrow(t);
|
||||
* }
|
||||
* };
|
||||
* final List<String> strList = list.stream()
|
||||
* .map(mapper).collect(Collectors.toList());
|
||||
* </pre>
|
||||
* as follows:
|
||||
* <pre>
|
||||
* final List<O> list;
|
||||
* final Method m;
|
||||
* final List<String> strList = Functions.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 <O> The streams element type.
|
||||
* @param pStream The stream, which is being converted.
|
||||
* @return The {@link FailableStream}, which has been created by
|
||||
* converting the stream.
|
||||
*/
|
||||
public static <O> FailableStream<O> stream(Collection<O> pStream) {
|
||||
return stream(pStream.stream());
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -16,7 +16,9 @@
|
|||
*/
|
||||
package org.apache.commons.lang3;
|
||||
|
||||
import static org.junit.jupiter.api.Assertions.*;
|
||||
import static org.junit.jupiter.api.Assertions.assertEquals;
|
||||
import static org.junit.jupiter.api.Assertions.assertSame;
|
||||
import static org.junit.jupiter.api.Assertions.fail;
|
||||
|
||||
import java.lang.reflect.UndeclaredThrowableException;
|
||||
import java.util.ArrayList;
|
||||
|
|
@ -62,7 +64,7 @@ class StreamsTest {
|
|||
}
|
||||
}
|
||||
|
||||
protected <T extends Throwable> FailableConsumer<String,T> asIntConsumer(T pThrowable) {
|
||||
protected <T extends Throwable> FailableConsumer<String, T> asIntConsumer(T pThrowable) {
|
||||
return (s) -> {
|
||||
final Integer i = Integer.valueOf(s);
|
||||
if (i.intValue() == 4) {
|
||||
|
|
@ -105,7 +107,9 @@ class StreamsTest {
|
|||
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
|
||||
final List<Integer> output = Functions.stream(input)
|
||||
.map((s) -> Integer.valueOf(s))
|
||||
.filter((i) -> { return i.intValue() %2 == 0;})
|
||||
.filter((i) -> {
|
||||
return i.intValue() %2 == 0;
|
||||
})
|
||||
.collect(Collectors.toList());
|
||||
assertEvenNumbers(output);
|
||||
}
|
||||
|
|
@ -117,7 +121,7 @@ class StreamsTest {
|
|||
}
|
||||
}
|
||||
|
||||
protected <T extends Throwable> FailablePredicate<Integer,T> asIntPredicate(T pThrowable) {
|
||||
protected <T extends Throwable> FailablePredicate<Integer, T> asIntPredicate(T pThrowable) {
|
||||
return (i) -> {
|
||||
if (i.intValue() == 5) {
|
||||
if (pThrowable != null) {
|
||||
|
|
|
|||
Loading…
Reference in New Issue