Merge pull request #2447 from earth001/master

BAEL-1079

libraries/pom.xml

@@ -186,11 +186,11 @@
 			<artifactId>rome</artifactId>
 			<version>${rome.version}</version>
 		</dependency>
-	    <dependency>
+		<dependency>
-	      <groupId>io.specto</groupId>
+			<groupId>io.specto</groupId>
-	      <artifactId>hoverfly-java</artifactId>
+			<artifactId>hoverfly-java</artifactId>
-	      <version>0.8.0</version>
+			<version>0.8.0</version>
-	    </dependency>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.httpcomponents</groupId>
 			<artifactId>httpclient</artifactId>
@@ -385,7 +385,7 @@
 		<dependency>
 			<groupId>one.util</groupId>
 			<artifactId>streamex</artifactId>
-			<version>0.6.5</version>
+			<version>${streamex.version}</version>
 		</dependency>
 		<dependency>
 			<groupId>org.jooq</groupId>
@@ -472,11 +472,16 @@
 			<artifactId>noexception</artifactId>
 			<version>1.1.0</version>
 		</dependency>
-    <dependency>
+		<dependency>
 			<groupId>org.eclipse.collections</groupId>
 			<artifactId>eclipse-collections</artifactId>
 			<version>${eclipse-collections.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>io.vavr</groupId>
+			<artifactId>vavr</artifactId>
+			<version>${vavr.version}</version>
+		</dependency>
 	</dependencies>
 	<properties>
 		<multiverse.version>0.7.0</multiverse.version>
@@ -519,6 +524,8 @@
 		<bytebuddy.version>1.7.1</bytebuddy.version>
 		<pcollections.version>2.1.2</pcollections.version>
 		<rome.version>1.0</rome.version>
-    <eclipse-collections.version>8.2.0</eclipse-collections.version>
+		<eclipse-collections.version>8.2.0</eclipse-collections.version>
+		<streamex.version>0.6.5</streamex.version>
+		<vavr.version>0.9.0</vavr.version>
 	</properties>
 </project>

libraries/src/main/java/com/baeldung/distinct/DistinctWithJavaFunction.java

@@ -0,0 +1,15 @@
+package com.baeldung.distinct;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+public class DistinctWithJavaFunction {
+
+    public static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
+        Map<Object, Boolean> seen = new ConcurrentHashMap<>();
+        return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
+    }
+
+}

libraries/src/main/java/com/baeldung/distinct/Person.java

@@ -0,0 +1,65 @@
+package com.baeldung.distinct;
+
+public class Person {
+    int age;
+    String name;
+    String email;
+
+    public Person(int age, String name, String email) {
+        super();
+        this.age = age;
+        this.name = name;
+        this.email = email;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Person [age=");
+        builder.append(age);
+        builder.append(", name=");
+        builder.append(name);
+        builder.append(", email=");
+        builder.append(email);
+        builder.append("]");
+        return builder.toString();
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((email == null) ? 0 : email.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Person other = (Person) obj;
+        if (email == null) {
+            if (other.email != null)
+                return false;
+        } else if (!email.equals(other.email))
+            return false;
+        return true;
+    }
+
+}

libraries/src/test/java/com/baeldung/distinct/DistinctWithEclipseCollectionsUnitTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.distinct;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.List;
+
+import org.eclipse.collections.impl.block.factory.HashingStrategies;
+import org.eclipse.collections.impl.utility.ListIterate;
+import org.junit.Before;
+import org.junit.Test;
+
+public class DistinctWithEclipseCollectionsUnitTest {
+    List<Person> personList;
+
+    @Before
+    public void init() {
+        personList = PersonDataGenerator.getPersonListWithFakeValues();
+    }
+
+    @Test
+    public void whenFilterListByName_thenSizeShouldBe4() {
+        List<Person> personListFiltered = ListIterate.distinct(personList, HashingStrategies.fromFunction(Person::getName));
+        assertTrue(personListFiltered.size() == 4);
+    }
+
+    @Test
+    public void whenFilterListByAge_thenSizeShouldBe2() {
+        List<Person> personListFiltered = ListIterate.distinct(personList, HashingStrategies.fromIntFunction(Person::getAge));
+        assertTrue(personListFiltered.size() == 2);
+    }
+
+}

libraries/src/test/java/com/baeldung/distinct/DistinctWithJavaFunctionUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.distinct;
+
+import static org.junit.Assert.assertTrue;
+import static com.baeldung.distinct.DistinctWithJavaFunction.distinctByKey;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class DistinctWithJavaFunctionUnitTest {
+    List<Person> personList;
+
+    @Before
+    public void init() {
+        personList = PersonDataGenerator.getPersonListWithFakeValues();
+    }
+
+    @Test
+    public void whenFilterListByName_thenSizeShouldBe4() {
+        List<Person> personListFiltered = personList.stream()
+            .filter(distinctByKey(p -> p.getName()))
+            .collect(Collectors.toList());
+        assertTrue(personListFiltered.size() == 4);
+    }
+
+    @Test
+    public void whenFilterListByAge_thenSizeShouldBe2() {
+        List<Person> personListFiltered = personList.stream()
+            .filter(distinctByKey(p -> p.getAge()))
+            .collect(Collectors.toList());
+        assertTrue(personListFiltered.size() == 2);
+    }
+
+    @Test
+    public void whenFilterListWithDefaultDistinct_thenSizeShouldBe5() {
+        List<Person> personListFiltered = personList.stream()
+            .distinct()
+            .collect(Collectors.toList());
+        assertTrue(personListFiltered.size() == 5);
+    }
+
+}

libraries/src/test/java/com/baeldung/distinct/DistinctWithStreamexUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.distinct;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import one.util.streamex.StreamEx;
+
+public class DistinctWithStreamexUnitTest {
+    List<Person> personList;
+
+    @Before
+    public void init() {
+        personList = PersonDataGenerator.getPersonListWithFakeValues();
+    }
+
+    @Test
+    public void whenFilterListByName_thenSizeShouldBe4() {
+        List<Person> personListFiltered = StreamEx.of(personList)
+            .distinct(Person::getName)
+            .toList();
+        assertTrue(personListFiltered.size() == 4);
+    }
+
+    @Test
+    public void whenFilterListByAge_thenSizeShouldBe2() {
+        List<Person> personListFiltered = StreamEx.of(personList)
+            .distinct(Person::getAge)
+            .toList();
+        assertTrue(personListFiltered.size() == 2);
+    }
+
+}

libraries/src/test/java/com/baeldung/distinct/DistinctWithVavrUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.distinct;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class DistinctWithVavrUnitTest {
+    List<Person> personList;
+
+    @Before
+    public void init() {
+        personList = PersonDataGenerator.getPersonListWithFakeValues();
+    }
+
+    @Test
+    public void whenFilterListByName_thenSizeShouldBe4() {
+        List<Person> personListFiltered = io.vavr.collection.List.ofAll(personList)
+            .distinctBy(Person::getName)
+            .toJavaList();
+        assertTrue(personListFiltered.size() == 4);
+    }
+
+    @Test
+    public void whenFilterListByAge_thenSizeShouldBe2() {
+        List<Person> personListFiltered = io.vavr.collection.List.ofAll(personList)
+            .distinctBy(Person::getAge)
+            .toJavaList();
+        assertTrue(personListFiltered.size() == 2);
+    }
+
+}

libraries/src/test/java/com/baeldung/distinct/PersonDataGenerator.java

@@ -0,0 +1,19 @@
+package com.baeldung.distinct;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class PersonDataGenerator {
+
+    public static List<Person> getPersonListWithFakeValues() {
+        // @formatter:off
+        return Arrays.asList(
+            new Person(20, "Jhon", "jhon@test.com"), 
+            new Person(20, "Jhon", "jhon1@test.com"), 
+            new Person(20, "Jhon", "jhon2@test.com"), 
+            new Person(21, "Tom", "Tom@test.com"), 
+            new Person(21, "Mark", "Mark@test.com"),
+            new Person(20, "Julia", "jhon@test.com"));
+        // @formatter:on
+    }
+}