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8252399: Update mapMulti documentation to use type test pattern inste…
…ad of instanceof once JEP 375 exits preview

Reviewed-by: dfuchs, psandoz, smarks
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pconcannon committed Mar 9, 2021
1 parent 0f2402d commit fbe40e8926ff4376f945455c3d4e8ed20277eeba
Showing with 80 additions and 6 deletions.
  1. +8 −6 src/java.base/share/classes/java/util/stream/Stream.java
  2. +72 −0 test/jdk/java/util/stream/examples/JavadocExamples.java
@@ -340,6 +340,8 @@
*/
DoubleStream flatMapToDouble(Function<? super T, ? extends DoubleStream> mapper);

// THE EXAMPLES USED IN THE JAVADOC MUST BE IN SYNC WITH THEIR CORRESPONDING
// TEST IN test/jdk/java/util/stream/examples/JavadocExamples.java.
/**
* Returns a stream consisting of the results of replacing each element of
* this stream with multiple elements, specifically zero or more elements.
@@ -386,8 +388,8 @@
* <pre>{@code
* Stream<Number> numbers = ... ;
* List<Integer> integers = numbers.<Integer>mapMulti((number, consumer) -> {
* if (number instanceof Integer)
* consumer.accept((Integer) number);
* if (number instanceof Integer i)
* consumer.accept(i);
* })
* .collect(Collectors.toList());
* }</pre>
@@ -397,8 +399,8 @@
* <pre>{@code
* class C {
* static void expandIterable(Object e, Consumer<Object> c) {
* if (e instanceof Iterable) {
* for (Object ie: (Iterable<?>) e) {
* if (e instanceof Iterable<?> elements) {
* for (Object ie : elements) {
* expandIterable(ie, c);
* }
* } else if (e != null) {
@@ -407,8 +409,8 @@
* }
*
* public static void main(String[] args) {
* Stream<Object> stream = ...;
* Stream<Object> expandedStream = stream.mapMulti(C::expandIterable);
* var nestedList = List.of(1, List.of(2, List.of(3, 4)), 5);
* Stream<Object> expandedStream = nestedList.stream().mapMulti(C::expandIterable);
* }
* }
* }</pre>
@@ -0,0 +1,72 @@
/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import org.testng.annotations.Test;

import java.util.List;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static org.testng.Assert.assertEquals;

/*
* THE CONTENTS OF THIS FILE HAVE TO BE IN SYNC WITH THE EXAMPLES USED IN THE JAVADOC.
*
* @test
* @run testng/othervm JavadocExamples
* @summary Checks to ensure example code displayed in the API documentation of
* java/util/Stream compiles correctly.
*/
public class JavadocExamples {

// From mapMulti
@Test
public void testNumberIntegerExample() {
Stream<Number> numbers = Stream.of(1, 2, 3.0);
List<Integer> integers = numbers.<Integer>mapMulti((number, consumer) -> {
if (number instanceof Integer i)
consumer.accept(i);
})
.collect(Collectors.toList());

assertEquals(integers, List.of(1,2));
}
@Test
public void testExpandIterableExample() {
var nestedList = List.of(1, List.of(2, List.of(3, 4)), 5);
Stream<Object> expandedStream = nestedList.stream().mapMulti(C::expandIterable);

assertEquals(expandedStream.toList(), List.of(1,2,3,4,5));
}
static class C {
static void expandIterable(Object e, Consumer<Object> c) {
if (e instanceof Iterable<?> elements) {
for (Object ie : elements) {
expandIterable(ie, c);
}
} else if (e != null) {
c.accept(e);
}
}
}
}

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