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[BAEL-3292] Add missing code snippets from the Java 8 groupingBy article

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The Tuple had to be changed because it required an equals/hashcode

Also: formatted with eclipse profile
This commit is contained in:
Martin van Wingerden
2019-10-23 12:04:31 +02:00
parent bcf119bf1a
commit a42fc708fb
2 changed files with 58 additions and 19 deletions
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46
core-java-modules/core-java-8/src/test/java/com/baeldung/java_8_features/groupingby/Java8GroupingByCollectorUnitTest.java
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@@ -1,15 +1,32 @@
package com.baeldung.java_8_features.groupingby;
import com.baeldung.java_8_features.groupingby.BlogPost;
import com.baeldung.java_8_features.groupingby.BlogPostType;
import org.junit.Test;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.averagingInt;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.groupingByConcurrent;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.summarizingInt;
import static java.util.stream.Collectors.summingInt;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;
import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import java.util.*;
import java.util.Arrays;
import java.util.EnumMap;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.*;
import static org.junit.Assert.*;
import org.junit.Test;
public class Java8GroupingByCollectorUnitTest {
@@ -180,4 +197,19 @@ public class Java8GroupingByCollectorUnitTest {
assertEquals(15, newsLikeStatistics.getMin());
}
@Test
public void givenAListOfPosts_whenGroupedByComplexMapKeyType_thenGetAMapBetweenTupleAndList() {
Map<Tuple, List<BlogPost>> postsPerTypeAndAuthor = posts.stream()
.collect(groupingBy(post -> new Tuple(post.getType(), post.getAuthor())));
List<BlogPost> result = postsPerTypeAndAuthor.get(new Tuple(BlogPostType.GUIDE, "Author 1"));
assertThat(result.size()).isEqualTo(1);
BlogPost blogPost = result.get(0);
assertThat(blogPost.getTitle()).isEqualTo("Programming guide");
assertThat(blogPost.getType()).isEqualTo(BlogPostType.GUIDE);
assertThat(blogPost.getAuthor()).isEqualTo("Author 1");
}
}