Merge branch 'master' of https://github.com/eugenp/tutorials

.gitignore

@@ -84,4 +84,10 @@ software-security/sql-injection-samples/derby.log
 spring-soap/src/main/java/com/baeldung/springsoap/gen/
 /report-*.json
 transaction.log
-*-shell.log
+*-shell.log
+
+apache-cxf/cxf-aegis/baeldung.xml
+apache-fop/src/test/resources/input.xml
+apache-fop/src/test/resources/output_herold.pdf
+apache-fop/src/test/resources/output_html2fo.pdf
+apache-fop/src/test/resources/output_jtidy.pdf

algorithms-miscellaneous-3/README.md

@@ -16,4 +16,6 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)
 - [Interpolation Search in Java](https://www.baeldung.com/java-interpolation-search)
 - [The K-Means Clustering Algorithm in Java](https://www.baeldung.com/java-k-means-clustering-algorithm)
+- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
+- [Breadth-First Search Algorithm in Java](https://www.baeldung.com/java-breadth-first-search)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-2) [[next -->]](/algorithms-miscellaneous-4)

algorithms-miscellaneous-4/README.md

@@ -1,7 +1,6 @@
 ## Algorithms - Miscellaneous
 
-This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](/../algorithms-sorting) and
-[genetic algorithms](/../algorithms-genetic), have their own dedicated modules. 
+This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](https://github.com/eugenp/tutorials/blob/algorithms-sorting) and [genetic algorithms](https://github.com/eugenp/tutorials/blob/algorithms-genetic), have their own dedicated modules.
 
 ### Relevant articles:
 
@@ -12,4 +11,4 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
 - [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
 - [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
-- More articles: [[<-- prev]](/../algorithms-miscellaneous-3) [[next -->]](/../algorithms-miscellaneous-5)
+- More articles: [[<-- prev]](/algorithms-miscellaneous-3) [[next -->]](/algorithms-miscellaneous-5)

algorithms-miscellaneous-5/README.md

@@ -8,4 +8,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Converting Between Byte Arrays and Hexadecimal Strings in Java](https://www.baeldung.com/java-byte-arrays-hex-strings)
 - [Reversing a Binary Tree in Java](https://www.baeldung.com/java-reversing-a-binary-tree)
 - [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
+- [Knapsack Problem Implementation in Java](https://www.baeldung.com/java-knapsack)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-4)

algorithms-sorting/README.md

@@ -17,3 +17,4 @@ This module contains articles about sorting algorithms.
 - [Sorting Strings by Contained Numbers in Java](https://www.baeldung.com/java-sort-strings-contained-numbers)
 - [Radix Sort in Java](https://www.baeldung.com/java-radix-sort)
 - [Sorting a String Alphabetically in Java](https://www.baeldung.com/java-sort-string-alphabetically)
+- [Bucket Sort in Java](https://www.baeldung.com/java-bucket-sort)

code-generation/pom.xml

@@ -12,10 +12,16 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>com.google.auto.value</groupId>
+            <artifactId>auto-value-annotations</artifactId>
+            <version>${auto-value.version}</version>
+        </dependency>
         <dependency>
             <groupId>com.google.auto.value</groupId>
             <artifactId>auto-value</artifactId>
             <version>${auto-value.version}</version>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>com.google.auto.factory</groupId>
@@ -43,9 +49,9 @@
     </dependencies>
 
     <properties>
-        <auto-value.version>1.3</auto-value.version>
-        <auto-factory.version>1.0-beta5</auto-factory.version>
-        <auto-service.version>1.0-rc5</auto-service.version>
+        <auto-value.version>1.6.6</auto-value.version>
+        <auto-factory.version>1.0-beta6</auto-factory.version>
+        <auto-service.version>1.0-rc6</auto-service.version>
         <guice.version>4.2.0</guice.version>
     </properties>
 

code-generation/src/main/java/com/baeldung/autovalue/Person.java

@@ -0,0 +1,38 @@
+package com.baeldung.autovalue;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import com.google.auto.value.AutoValue;
+
+@AutoValue
+public abstract class Person {
+
+    public abstract String name();
+
+    public abstract List<String> favoriteMovies();
+
+    public static Builder builder() {
+        return new AutoValue_Person.Builder();
+    }
+
+    @AutoValue.Builder
+    public static abstract class Builder {
+
+        public abstract Builder name(String value);
+
+        public abstract Builder favoriteMovies(List<String> value);
+
+        abstract List<String> favoriteMovies();
+
+        abstract Person autoBuild();
+
+        public Person build() {
+            List<String> favoriteMovies = favoriteMovies();
+            List<String> copy = Collections.unmodifiableList(new ArrayList<>(favoriteMovies));
+            favoriteMovies(copy);
+            return autoBuild();
+        }
+    }
+}

code-generation/src/test/java/com/baeldung/autovalue/PersonUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.autovalue;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.Test;
+
+/**
+ * Unit Test which verifies that the {@link Person} value object creates defensive copies of its favoriteMovies list.
+ */
+public class PersonUnitTest {
+
+    @Test
+    public void givenNewPerson_whenModifyOriginalList_thenValueObjectIsNotAlsoModified() {
+        // GIVEN new Person
+        List<String> originalFavoriteMoviesList = new ArrayList<String>();
+        originalFavoriteMoviesList.add("Training Day");
+        originalFavoriteMoviesList.add("Fast and the Furious");
+        Person person = Person.builder()
+            .name("Dan")
+            .favoriteMovies(originalFavoriteMoviesList)
+            .build();
+
+        // WHEN modify original list
+        originalFavoriteMoviesList.add("Friday");
+
+        // THEN Person remains unaffected
+        assertFalse(person.favoriteMovies()
+            .contains("Friday"));
+        assertEquals(2, person.favoriteMovies()
+            .size());
+    }
+
+}

core-groovy-2/README.md

@@ -12,4 +12,5 @@ This module contains articles about core Groovy concepts
 - [Concatenate Strings with Groovy](https://www.baeldung.com/groovy-concatenate-strings)
 - [Metaprogramming in Groovy](https://www.baeldung.com/groovy-metaprogramming)
 - [A Quick Guide to Working with Web Services in Groovy](https://www.baeldung.com/groovy-web-services)
+- [Categories in Groovy](https://www.baeldung.com/groovy-categories)
 - [[<-- Prev]](/core-groovy)

core-groovy-collections/README.md

@@ -5,4 +5,6 @@ This module contains articles about Groovy core collections
 ## Relevant articles:
 
 - [Maps in Groovy](https://www.baeldung.com/groovy-maps)
-
+- [Finding Elements in Collections in Groovy](https://www.baeldung.com/groovy-collections-find-elements)
+- [Lists in Groovy](https://www.baeldung.com/groovy-lists)
+- [A Quick Guide to Iterating a Map in Groovy](https://www.baeldung.com/groovy-map-iterating)

core-groovy-collections/src/test/groovy/com/baeldung/find/ListFindUnitTest.groovy

@@ -1,11 +1,11 @@
-package com.baeldung.lists
+package com.baeldung.find
 
-import com.baeldung.Person
+import com.baeldung.find.Person
 import org.junit.Test
 
 import static org.junit.Assert.*
 
-class ListUnitTest {
+class ListFindUnitTest {
 
     private final personList = [
       new Person("Regina", "Fitzpatrick", 25),

core-groovy-collections/src/test/groovy/com/baeldung/find/MapFindUnitTest.groovy

@@ -1,11 +1,11 @@
-package com.baeldung.map
+package com.baeldung.find
 
-import com.baeldung.Person
+import com.baeldung.find.Person
 import org.junit.Test
 
 import static org.junit.Assert.*
 
-class MapUnitTest {
+class MapFindUnitTest {
 
     private final personMap = [
       Regina : new Person("Regina", "Fitzpatrick", 25),
@@ -13,84 +13,6 @@ class MapUnitTest {
       Lucian : new Person("Lucian", "Walter", 30)
     ]
 
-    @Test
-    void whenUsingEach_thenMapIsIterated() {
-        def map = [
-            'FF0000' : 'Red',
-            '00FF00' : 'Lime',
-            '0000FF' : 'Blue',
-            'FFFF00' : 'Yellow'
-        ]
-
-        map.each { println "Hex Code: $it.key = Color Name: $it.value" }
-    }
-
-    @Test
-    void whenUsingEachWithEntry_thenMapIsIterated() {
-        def map = [
-            'E6E6FA' : 'Lavender',
-            'D8BFD8' : 'Thistle',
-            'DDA0DD' : 'Plum',
-        ]
-
-        map.each { entry -> println "Hex Code: $entry.key = Color Name: $entry.value" }
-    }
-
-    @Test
-    void whenUsingEachWithKeyAndValue_thenMapIsIterated() {
-        def map = [
-            '000000' : 'Black',
-            'FFFFFF' : 'White',
-            '808080' : 'Gray'
-        ]
-
-        map.each { key, val ->
-            println "Hex Code: $key = Color Name $val"
-        }
-    }
-
-    @Test
-    void whenUsingEachWithIndexAndEntry_thenMapIsIterated() {
-        def map = [
-            '800080' : 'Purple',
-            '4B0082' : 'Indigo',
-            '6A5ACD' : 'Slate Blue'
-        ]
-
-        map.eachWithIndex { entry, index ->
-            def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
-            println "$indent Hex Code: $entry.key = Color Name: $entry.value"
-        }
-    }
-
-    @Test
-    void whenUsingEachWithIndexAndKeyAndValue_thenMapIsIterated() {
-        def map = [
-            'FFA07A' : 'Light Salmon',
-            'FF7F50' : 'Coral',
-            'FF6347' : 'Tomato',
-            'FF4500' : 'Orange Red'
-        ]
-
-        map.eachWithIndex { key, val, index ->
-            def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
-            println "$indent Hex Code: $key = Color Name: $val"
-        }
-    }
-
-    @Test
-    void whenUsingForLoop_thenMapIsIterated() {
-        def map = [
-            '2E8B57' : 'Seagreen',
-            '228B22' : 'Forest Green',
-            '008000' : 'Green'
-        ]
-
-        for (entry in map) {
-            println "Hex Code: $entry.key = Color Name: $entry.value"
-        }
-    }
-
     @Test
     void whenMapContainsKeyElement_thenCheckReturnsTrue() {
         def map = [a: 'd', b: 'e', c: 'f']

core-groovy-collections/src/test/groovy/com/baeldung/find/Person.groovy

@@ -1,4 +1,4 @@
-package com.baeldung
+package com.baeldung.find
 
 class Person {
     private String firstname

core-groovy-collections/src/test/groovy/com/baeldung/find/SetFindUnitTest.groovy

@@ -1,10 +1,10 @@
-package com.baeldung.set
+package com.baeldung.find
 
 import org.junit.Test
 
 import static org.junit.Assert.assertTrue
 
-class SetUnitTest {
+class SetFindUnitTest {
 
     @Test
     void whenSetContainsElement_thenCheckReturnsTrue() {

core-groovy-collections/src/test/groovy/com/baeldung/iteratemap/IterateMapUnitTest.groovy

@@ -0,0 +1,87 @@
+package com.baeldung.iteratemap
+
+import com.baeldung.find.Person
+import org.junit.Test
+
+import static org.junit.Assert.*
+
+class IterateMapUnitTest {
+
+    @Test
+    void whenUsingEach_thenMapIsIterated() {
+        def map = [
+                'FF0000' : 'Red',
+                '00FF00' : 'Lime',
+                '0000FF' : 'Blue',
+                'FFFF00' : 'Yellow'
+        ]
+
+        map.each { println "Hex Code: $it.key = Color Name: $it.value" }
+    }
+
+    @Test
+    void whenUsingEachWithEntry_thenMapIsIterated() {
+        def map = [
+                'E6E6FA' : 'Lavender',
+                'D8BFD8' : 'Thistle',
+                'DDA0DD' : 'Plum',
+        ]
+
+        map.each { entry -> println "Hex Code: $entry.key = Color Name: $entry.value" }
+    }
+
+    @Test
+    void whenUsingEachWithKeyAndValue_thenMapIsIterated() {
+        def map = [
+                '000000' : 'Black',
+                'FFFFFF' : 'White',
+                '808080' : 'Gray'
+        ]
+
+        map.each { key, val ->
+            println "Hex Code: $key = Color Name $val"
+        }
+    }
+
+    @Test
+    void whenUsingEachWithIndexAndEntry_thenMapIsIterated() {
+        def map = [
+                '800080' : 'Purple',
+                '4B0082' : 'Indigo',
+                '6A5ACD' : 'Slate Blue'
+        ]
+
+        map.eachWithIndex { entry, index ->
+            def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
+            println "$indent Hex Code: $entry.key = Color Name: $entry.value"
+        }
+    }
+
+    @Test
+    void whenUsingEachWithIndexAndKeyAndValue_thenMapIsIterated() {
+        def map = [
+                'FFA07A' : 'Light Salmon',
+                'FF7F50' : 'Coral',
+                'FF6347' : 'Tomato',
+                'FF4500' : 'Orange Red'
+        ]
+
+        map.eachWithIndex { key, val, index ->
+            def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
+            println "$indent Hex Code: $key = Color Name: $val"
+        }
+    }
+
+    @Test
+    void whenUsingForLoop_thenMapIsIterated() {
+        def map = [
+                '2E8B57' : 'Seagreen',
+                '228B22' : 'Forest Green',
+                '008000' : 'Green'
+        ]
+
+        for (entry in map) {
+            println "Hex Code: $entry.key = Color Name: $entry.value"
+        }
+    }
+}

core-groovy-collections/src/test/groovy/com/baeldung/lists/ListUnitTest.groovy

@@ -1,9 +1,9 @@
-package com.baeldung.groovy.lists
+package com.baeldung.lists
 
 import static groovy.test.GroovyAssert.*
 import org.junit.Test
 
-class ListTest{
+class ListUnitTest {
 
     @Test
     void testCreateList() {

core-groovy-collections/src/test/groovy/com/baeldung/maps/MapTest.groovy

@@ -1,4 +1,4 @@
-package com.baeldung.map;
+package com.baeldung.maps;
 
 import static groovy.test.GroovyAssert.*
 import org.junit.Test

core-groovy/README.md

@@ -8,11 +8,8 @@ This module contains articles about core Groovy concepts
 - [Working with JSON in Groovy](https://www.baeldung.com/groovy-json)
 - [Reading a File in Groovy](https://www.baeldung.com/groovy-file-read)
 - [Types of Strings in Groovy](https://www.baeldung.com/groovy-strings)
-- [A Quick Guide to Iterating a Map in Groovy](https://www.baeldung.com/groovy-map-iterating)
 - [An Introduction to Traits in Groovy](https://www.baeldung.com/groovy-traits)
 - [Closures in Groovy](https://www.baeldung.com/groovy-closures)
-- [Finding Elements in Collections in Groovy](https://www.baeldung.com/groovy-collections-find-elements)
-- [Lists in Groovy](https://www.baeldung.com/groovy-lists)
 - [Converting a String to a Date in Groovy](https://www.baeldung.com/groovy-string-to-date)
 - [Guide to I/O in Groovy](https://www.baeldung.com/groovy-io)
 - [[More -->]](/core-groovy-2)

core-groovy/src/test/groovy/com/baeldung/map/MapTest.groovy

@@ -1,148 +0,0 @@
-package com.baeldung.groovy.map;
-
-import static groovy.test.GroovyAssert.*
-import org.junit.Test
-
-class MapTest{
-
-    @Test
-    void createMap() {
-
-        def emptyMap = [:]
-        assertNotNull(emptyMap)
-
-        assertTrue(emptyMap instanceof java.util.LinkedHashMap)
-
-        def map = [name:"Jerry", age: 42, city: "New York"]
-        assertTrue(map.size() == 3)
-    }
-
-    @Test
-    void addItemsToMap() {
-
-        def map = [name:"Jerry"]
-
-        map["age"] = 42
-
-        map.city = "New York"
-
-        def hobbyLiteral = "hobby"
-        def hobbyMap = [(hobbyLiteral): "Singing"]
-        map.putAll(hobbyMap)
-
-        assertTrue(map == [name:"Jerry", age: 42, city: "New York", hobby:"Singing"])
-        assertTrue(hobbyMap.hobby == "Singing")
-        assertTrue(hobbyMap[hobbyLiteral] == "Singing")
-        
-        map.plus([1:20]) // returns new map
-
-        map << [2:30]
-
-    }
-
-    @Test
-    void getItemsFromMap() {
-
-        def map = [name:"Jerry", age: 42, city: "New York", hobby:"Singing"]
-
-        assertTrue(map["name"] == "Jerry")
-
-        assertTrue(map.name == "Jerry")
-
-        def propertyAge = "age"
-        assertTrue(map[propertyAge] == 42)
-    }
-
-    @Test
-    void removeItemsFromMap() {
-
-        def map = [1:20, a:30, 2:42, 4:34, ba:67, 6:39, 7:49]
-
-        def minusMap = map.minus([2:42, 4:34]);
-        assertTrue(minusMap == [1:20, a:30, ba:67, 6:39, 7:49])
-
-        minusMap.removeAll{it -> it.key instanceof String}
-        assertTrue( minusMap == [ 1:20, 6:39, 7:49])
-
-        minusMap.retainAll{it -> it.value %2 == 0}
-        assertTrue( minusMap == [1:20])
-    }
-
-    @Test
-    void iteratingOnMaps(){
-        def map = [name:"Jerry", age: 42, city: "New York", hobby:"Singing"]
-
-        map.each{ entry -> println "$entry.key: $entry.value" }
-
-        map.eachWithIndex{ entry, i -> println "$i $entry.key: $entry.value" }
-
-        map.eachWithIndex{ key, value, i -> println "$i $key: $value" }
-    }
-
-    @Test
-    void filteringAndSearchingMaps(){
-        def map = [name:"Jerry", age: 42, city: "New York", hobby:"Singing"]
-
-        assertTrue(map.find{ it.value == "New York"}.key == "city")
-
-        assertTrue(map.findAll{ it.value == "New York"} == [city : "New York"])
-
-        map.grep{it.value == "New York"}.each{ it -> assertTrue(it.key == "city" && it.value == "New York")}
-
-        assertTrue(map.every{it -> it.value instanceof String} == false)
-
-        assertTrue(map.any{it -> it.value instanceof String} == true)
-    }
-
-    @Test
-    void collect(){
-
-        def map = [1: [name:"Jerry", age: 42, city: "New York"],
-            2: [name:"Long", age: 25, city: "New York"],
-            3: [name:"Dustin", age: 29, city: "New York"],
-            4: [name:"Dustin", age: 34, city: "New York"]]
-
-        def names = map.collect{entry -> entry.value.name} // returns only list
-        assertTrue(names == ["Jerry", "Long", "Dustin", "Dustin"])
-
-        def uniqueNames = map.collect([] as HashSet){entry -> entry.value.name}
-        assertTrue(uniqueNames == ["Jerry", "Long", "Dustin"] as Set)
-
-        def idNames = map.collectEntries{key, value -> [key, value.name]}
-        assertTrue(idNames == [1:"Jerry", 2: "Long", 3:"Dustin", 4: "Dustin"])
-
-        def below30Names = map.findAll{it.value.age < 30}.collect{key, value -> value.name}
-        assertTrue(below30Names == ["Long", "Dustin"])
-
-
-    }
-
-    @Test
-    void group(){
-        def map = [1:20, 2: 40, 3: 11, 4: 93]
-
-        def subMap = map.groupBy{it.value % 2}
-        println subMap
-        assertTrue(subMap == [0:[1:20, 2:40 ], 1:[3:11, 4:93]])
-
-        def keySubMap = map.subMap([1, 2])
-        assertTrue(keySubMap == [1:20, 2:40])
-
-    }
-
-    @Test
-    void sorting(){
-        def map = [ab:20, a: 40, cb: 11, ba: 93]
-
-        def naturallyOrderedMap = map.sort()
-        assertTrue([a:40, ab:20, ba:93, cb:11] == naturallyOrderedMap)
-
-        def compSortedMap = map.sort({ k1, k2 -> k1 <=> k2 } as Comparator)
-        assertTrue([a:40, ab:20, ba:93, cb:11] == compSortedMap)
-
-        def cloSortedMap = map.sort({ it1, it2 -> it1.value <=> it1.value })
-        assertTrue([cb:11, ab:20, a:40, ba:93] == cloSortedMap)
-
-    }
-
-}

core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/Tuple.java

@@ -1,12 +1,12 @@
 package com.baeldung.java_8_features.groupingby;
 
+import java.util.Objects;
+
 public class Tuple {
+    private final BlogPostType type;
+    private final String author;
 
-    private BlogPostType type;
-    private String author;
-    
     public Tuple(BlogPostType type, String author) {
-        super();
         this.type = type;
         this.author = author;
     }
@@ -15,20 +15,27 @@ public class Tuple {
         return type;
     }
 
-    public void setType(BlogPostType type) {
-        this.type = type;
-    }
-
     public String getAuthor() {
         return author;
     }
 
-    public void setAuthor(String author) {
-        this.author = author;
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Tuple tuple = (Tuple) o;
+        return type == tuple.type && author.equals(tuple.author);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(type, author);
     }
 
     @Override
     public String toString() {
-        return "Tuple [type=" + type + ", author=" + author + ", getType()=" + getType() + ", getAuthor()=" + getAuthor() + ", getClass()=" + getClass() + ", hashCode()=" + hashCode() + ", toString()=" + super.toString() + "]";
+        return "Tuple{" + "type=" + type + ", author='" + author + '\'' + '}';
     }
 }

core-java-modules/core-java-8/src/test/java/com/baeldung/java_8_features/groupingby/Java8GroupingByCollectorUnitTest.java

@@ -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");
+    }
 }

core-java-modules/core-java-9-streams/README.md

@@ -0,0 +1,6 @@
+## Core Java 9 streams
+
+This module contains articles about Java 9 streams
+
+### Relevant Articles: 
+- [How to Break from Java Stream forEach](https://www.baeldung.com/java-break-stream-foreach)

core-java-modules/core-java-9-streams/pom.xml

@@ -0,0 +1,31 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-9-streams</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-9-streams</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-9-streams</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+    </properties>
+</project>

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/CustomForEach.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.Spliterator;
 import java.util.function.BiConsumer;

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/CustomSpliterator.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.Spliterator;
 import java.util.Spliterators;

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/CustomTakeWhile.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.function.Predicate;
 import java.util.stream.Stream;