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Centralize stream code in our own 'stream' package as 

a parallel to the JRE's java.util.stream package.

- Re-implement use of failable function interfaces based on our function
package.
- Deprecate old class.
- Remove trainling whitespace.
This commit is contained in:
Gary Gregory 2020-06-17 17:37:14 -04:00
parent 724c00f0e8
commit 8fcefb4f98
7 changed files with 698 additions and 11 deletions
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2
src/main/java/org/apache/commons/lang3/Functions.java
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@ -31,6 +31,7 @@
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.apache.commons.lang3.Streams.FailableStream;
import org.apache.commons.lang3.function.FailableBooleanSupplier;
import org.apache.commons.lang3.function.FailableDoubleBinaryOperator;
import org.apache.commons.lang3.function.FailableDoubleConsumer;
@ -39,7 +40,6 @@
import org.apache.commons.lang3.function.FailableIntSupplier;
import org.apache.commons.lang3.function.FailableLongConsumer;
import org.apache.commons.lang3.function.FailableLongSupplier;
import org.apache.commons.lang3.stream.Streams.FailableStream;
/**
* This class provides utility functions, and classes for working with the {@code java.util.function} package, or more

8
src/main/java/org/apache/commons/lang3/Streams.java
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@ -62,14 +62,18 @@
* @see Stream
* @see Functions
* @since 3.10
* @deprecated Use {@link org.apache.commons.lang3.stream.Streams}.
*/
@Deprecated
public class Streams {
/**
* A reduced, and simplified version of a {@link Stream} with
* failable method signatures.
* @param <O> The streams element type.
* @deprecated Use {@link org.apache.commons.lang3.stream.Streams.FailableStream}.
*/
@Deprecated
public static class FailableStream<O extends Object> {
private Stream<O> stream;
@ -435,6 +439,10 @@ public static <O> FailableStream<O> stream(final Collection<O> stream) {
return stream(stream.stream());
}
/**
* @deprecated Use {@link org.apache.commons.lang3.stream.Streams.ArrayCollector}.
*/
@Deprecated
public static class ArrayCollector<O> implements Collector<O, List<O>, O[]> {
private static final Set<Characteristics> characteristics = Collections.emptySet();
private final Class<O> elementType;

2
src/main/java/org/apache/commons/lang3/concurrent/Locks.java
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@ -24,7 +24,7 @@
import org.apache.commons.lang3.function.FailableFunction;
/**
/**
* Utility class for working with {@link java.util.concurrent.locks.Lock locked objects}. Locked objects are an
* alternative to synchronization.
*

2
src/main/java/org/apache/commons/lang3/function/Failable.java
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@ -32,7 +32,7 @@
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.apache.commons.lang3.Streams.FailableStream;
import org.apache.commons.lang3.stream.Streams.FailableStream;
/**
* This class provides utility functions, and classes for working with the {@code java.util.function} package, or more

492
src/main/java/org/apache/commons/lang3/stream/Streams.java Normal file
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@ -0,0 +1,492 @@
/*
* 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.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Set;
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 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>
* Consumer&lt;java.lang.reflect.Method&gt; consumer = (m) -&gt; {
* try {
* m.invoke(o, args);
* } catch (Throwable t) {
* throw Failable.rethrow(t);
* }
* };
* stream.forEach(consumer);
* </pre>
* Using a {@link FailableStream}, this can be rewritten as follows:
* <pre>
* Streams.failable(stream).forEach((m) -&gt; 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 3.10
*/
public class Streams {
public static class ArrayCollector<O> implements Collector<O, List<O>, O[]> {
private static final Set<Characteristics> characteristics = Collections.emptySet();
private final Class<O> elementType;
public ArrayCollector(final Class<O> elementType) {
this.elementType = elementType;
}
@Override
public BiConsumer<List<O>, O> accumulator() {
return List::add;
}
@Override
public Set<Characteristics> characteristics() {
return characteristics;
}
@Override
public BinaryOperator<List<O>> combiner() {
return (left, right) -> {
left.addAll(right);
return left;
};
}
@Override
public Function<List<O>, O[]> finisher() {
return list -> {
@SuppressWarnings("unchecked")
final O[] array = (O[]) Array.newInstance(elementType, list.size());
return list.toArray(array);
};
}
@Override
public Supplier<List<O>> supplier() {
return ArrayList::new;
}
}
/**
* A reduced, and simplified version of a {@link Stream} with
* failable method signatures.
* @param <O> The streams element type.
*/
public static class FailableStream<O extends Object> {
private Stream<O> stream;
private boolean terminated;
/**
* Constructs a new instance with the given {@code stream}.
* @param stream The stream.
*/
public FailableStream(final Stream<O> 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.
*
* \@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 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<O, ?> 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.
*
* \@apiNote
* 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<O, ?> predicate) {
assertNotTerminated();
return stream().anyMatch(Failable.asPredicate(predicate));
}
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
* {@code Collector}. A {@code 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 {@code 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>This is a terminal operation.
*
* <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 {@code ArrayList}), no
* additional synchronization is needed for a parallel reduction.
*
* \@apiNote
* 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:
* <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 {@code Collector}s together:
* <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 {@code Collector}
* @param collector the {@code 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 O, 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 {@code 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>This is a terminal operation.
*
* \@apiNote 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 {@code 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:
* <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 pupplier 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> pupplier, final BiConsumer<R, ? super O> accumulator, final BiConsumer<R, R> combiner) {
makeTerminated();
return stream().collect(pupplier, accumulator, combiner);
}
/**
* Returns a FailableStream consisting of the elements of this stream that match
* the given FailablePredicate.
*
* <p>This is an intermediate operation.
*
* @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<O> filter(final FailablePredicate<O, ?> 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>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.
*
* @param action a non-interfering action to perform on the elements
*/
public void forEach(final FailableConsumer<O, ?> action) {
makeTerminated();
stream().forEach(Failable.asConsumer(action));
}
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.
*
* @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<O, 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>This is a terminal operation.
*
* \@apiNote 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.
*
* @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 O reduce(final O identity, final BinaryOperator<O> 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<O> 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>
* final List&lt;O&gt; list;
* final Method m;
* final Function&lt;O,String&gt; mapper = (o) -&gt; {
* try {
* return (String) m.invoke(o);
* } catch (Throwable t) {
* throw Failable.rethrow(t);
* }
* };
* final List&lt;String&gt; strList = list.stream()
* .map(mapper).collect(Collectors.toList());
* </pre>
* as follows:
* <pre>
* final List&lt;O&gt; list;
* final Method m;
* final List&lt;String&gt; strList = Failable.stream(list.stream())
* .map((o) -&gt; (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 stream The stream, which is being converted.
* @return The {@link FailableStream}, which has been created by
* converting the stream.
*/
public static <O> FailableStream<O> stream(final Collection<O> stream) {
return stream(stream.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>
* final List&lt;O&gt; list;
* final Method m;
* final Function&lt;O,String&gt; mapper = (o) -&gt; {
* try {
* return (String) m.invoke(o);
* } catch (Throwable t) {
* throw Failable.rethrow(t);
* }
* };
* final List&lt;String&gt; strList = list.stream()
* .map(mapper).collect(Collectors.toList());
* </pre>
* as follows:
* <pre>
* final List&lt;O&gt; list;
* final Method m;
* final List&lt;String&gt; strList = Failable.stream(list.stream())
* .map((o) -&gt; (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 stream The stream, which is being converted.
* @return The {@link FailableStream}, which has been created by
* converting the stream.
*/
public static <O> FailableStream<O> stream(final Stream<O> stream) {
return new FailableStream<>(stream);
}
/**
* Returns a {@code Collector} that accumulates the input elements into a
* new array.
*
* @param pElementType Type of an element in the array.
* @param <O> the type of the input elements
* @return a {@code Collector} which collects all the input elements into an
* array, in encounter order
*/
public static <O extends Object> Collector<O, ?, O[]> toArray(final Class<O> pElementType) {
return new ArrayCollector<>(pElementType);
}
}

16
src/test/java/org/apache/commons/lang3/StreamsTest.java
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@ -41,10 +41,10 @@
import org.junit.jupiter.api.function.Executable;
import org.xml.sax.SAXException;
class StreamsTest {
public class StreamsTest {
@Test
void testSimpleStreamMap() {
public void testSimpleStreamMap() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = Functions.stream(input).map(Integer::valueOf).collect(Collectors.toList());
assertEquals(6, output.size());
@ -54,7 +54,7 @@ void testSimpleStreamMap() {
}
@Test
void testSimpleStreamMapFailing() {
public void testSimpleStreamMapFailing() {
final List<String> input = Arrays.asList("1", "2", "3", "4 ", "5", "6");
final Executable testMethod = () -> Functions.stream(input).map(Integer::valueOf).collect(Collectors.toList());
final NumberFormatException thrown = assertThrows(NumberFormatException.class, testMethod);
@ -62,7 +62,7 @@ void testSimpleStreamMapFailing() {
}
@Test
void testSimpleStreamForEach() {
public void testSimpleStreamForEach() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = new ArrayList<>();
Functions.stream(input).forEach(s -> output.add(Integer.valueOf(s)));
@ -73,7 +73,7 @@ void testSimpleStreamForEach() {
}
@Test
void testToArray() {
public void testToArray() {
final String[] array = Arrays.asList("2", "3", "1").stream().collect(Streams.toArray(String.class));
assertNotNull(array);
assertEquals(3, array.length);
@ -92,7 +92,7 @@ protected <T extends Throwable> FailableConsumer<String, T> asIntConsumer(final
}
@TestFactory
Stream<DynamicTest> simpleStreamForEachFailing() {
public Stream<DynamicTest> simpleStreamForEachFailing() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
return Stream.of(
@ -127,7 +127,7 @@ Stream<DynamicTest> simpleStreamForEachFailing() {
}
@Test
void testSimpleStreamFilter() {
public void testSimpleStreamFilter() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = Functions.stream(input)
.map(Integer::valueOf)
@ -155,7 +155,7 @@ protected <T extends Throwable> FailablePredicate<Integer, T> asIntPredicate(fin
}
@TestFactory
Stream<DynamicTest> simpleStreamFilterFailing() {
public Stream<DynamicTest> simpleStreamFilterFailing() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = Functions.stream(input)
.map(Integer::valueOf)

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src/test/java/org/apache/commons/lang3/stream/StreamsTest.java Normal file
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@ -0,0 +1,187 @@
/*
* 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 static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.core.Is.is;
import static org.hamcrest.core.IsEqual.equalTo;
import static org.hamcrest.core.IsNull.nullValue;
import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.DynamicTest.dynamicTest;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.apache.commons.lang3.function.Failable;
import org.apache.commons.lang3.function.FailableConsumer;
import org.apache.commons.lang3.function.FailablePredicate;
import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestFactory;
import org.junit.jupiter.api.function.Executable;
import org.xml.sax.SAXException;
public class StreamsTest {
protected <T extends Throwable> FailableConsumer<String, T> asIntConsumer(final T pThrowable) {
return s -> {
final Integer i = Integer.valueOf(s);
if (i.intValue() == 4) {
throw pThrowable;
}
};
}
protected <T extends Throwable> FailablePredicate<Integer, T> asIntPredicate(final T pThrowable) {
return i -> {
if (i.intValue() == 5) {
if (pThrowable != null) {
throw pThrowable;
}
}
return i % 2 == 0;
};
}
private void assertEvenNumbers(final List<Integer> output) {
assertEquals(3, output.size());
for (int i = 0; i < 3; i++) {
assertEquals((i + 1) * 2, output.get(i).intValue());
}
}
@TestFactory
public Stream<DynamicTest> simpleStreamFilterFailing() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = Failable.stream(input).map(Integer::valueOf).filter(asIntPredicate(null))
.collect(Collectors.toList());
assertEvenNumbers(output);
return Stream.of(
dynamicTest("IllegalArgumentException", () -> {
final IllegalArgumentException iae = new IllegalArgumentException("Invalid argument: " + 5);
final Executable testMethod = () -> Failable.stream(input).map(Integer::valueOf)
.filter(asIntPredicate(iae)).collect(Collectors.toList());
final IllegalArgumentException thrown = assertThrows(IllegalArgumentException.class, testMethod);
assertThat(thrown.getMessage(), is(equalTo("Invalid argument: " + 5)));
}),
dynamicTest("OutOfMemoryError", () -> {
final OutOfMemoryError oome = new OutOfMemoryError();
final Executable testMethod = () -> Failable.stream(input).map(Integer::valueOf)
.filter(asIntPredicate(oome)).collect(Collectors.toList());
final OutOfMemoryError thrown = assertThrows(OutOfMemoryError.class, testMethod);
assertThat(thrown.getMessage(), is(nullValue()));
}),
dynamicTest("SAXException", () -> {
final SAXException se = new SAXException();
final Executable testMethod = () -> Failable.stream(input).map(Integer::valueOf)
.filter(asIntPredicate(se)).collect(Collectors.toList());
final UndeclaredThrowableException thrown = assertThrows(UndeclaredThrowableException.class,
testMethod);
assertAll(() -> assertThat(thrown.getMessage(), is(nullValue())),
() -> assertThat(thrown.getCause(), is(equalTo(se))));
}));
}
@TestFactory
public Stream<DynamicTest> simpleStreamForEachFailing() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
return Stream.of(
dynamicTest("IllegalArgumentException", () -> {
final IllegalArgumentException ise = new IllegalArgumentException();
final Executable testMethod = () -> Failable.stream(input).forEach(asIntConsumer(ise));
final IllegalArgumentException thrown = assertThrows(IllegalArgumentException.class, testMethod);
assertThat(thrown.getMessage(), is(nullValue()));
}),
dynamicTest("OutOfMemoryError", () -> {
final OutOfMemoryError oome = new OutOfMemoryError();
final Executable oomeTestMethod = () -> Failable.stream(input).forEach(asIntConsumer(oome));
final OutOfMemoryError oomeThrown = assertThrows(OutOfMemoryError.class, oomeTestMethod);
assertThat(oomeThrown.getMessage(), is(nullValue()));
}),
dynamicTest("SAXException", () -> {
final SAXException se = new SAXException();
final Executable seTestMethod = () -> Failable.stream(input).forEach(asIntConsumer(se));
final UndeclaredThrowableException seThrown = assertThrows(UndeclaredThrowableException.class,
seTestMethod);
assertAll(() -> assertThat(seThrown.getMessage(), is(nullValue())),
() -> assertThat(seThrown.getCause(), is(equalTo(se))));
}));
}
@Test
public void testSimpleStreamFilter() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = Failable.stream(input).map(Integer::valueOf).filter(i -> (i.intValue() % 2 == 0))
.collect(Collectors.toList());
assertEvenNumbers(output);
}
@Test
public void testSimpleStreamForEach() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = new ArrayList<>();
Failable.stream(input).forEach(s -> output.add(Integer.valueOf(s)));
assertEquals(6, output.size());
for (int i = 0; i < 6; i++) {
assertEquals(i + 1, output.get(i).intValue());
}
}
@Test
public void testSimpleStreamMap() {
final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
final List<Integer> output = Failable.stream(input).map(Integer::valueOf).collect(Collectors.toList());
assertEquals(6, output.size());
for (int i = 0; i < 6; i++) {
assertEquals(i + 1, output.get(i).intValue());
}
}
@Test
public void testSimpleStreamMapFailing() {
final List<String> input = Arrays.asList("1", "2", "3", "4 ", "5", "6");
final Executable testMethod = () -> Failable.stream(input).map(Integer::valueOf).collect(Collectors.toList());
final NumberFormatException thrown = assertThrows(NumberFormatException.class, testMethod);
assertEquals("For input string: \"4 \"", thrown.getMessage());
}
@Test
public void testToArray() {
final String[] array = Arrays.asList("2", "3", "1").stream().collect(Streams.toArray(String.class));
assertNotNull(array);
assertEquals(3, array.length);
assertEquals("2", array[0]);
assertEquals("3", array[1]);
assertEquals("1", array[2]);
}
}