BAEL-6334 Add example code for checking if a list element is in another list

core-java-modules/core-java-collections-list-5/pom.xml

@@ -24,6 +24,19 @@
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang3.version}</version>
         </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>4.4</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.26</version>
+            <scope>provided</scope>
+        </dependency>
     </dependencies>
 
     <properties>

core-java-modules/core-java-collections-list-5/src/main/java/com/baeldung/list/Country.java

@@ -0,0 +1,11 @@
+package com.baeldung.list;
+
+import lombok.Data;
+
+@Data
+public class Country {
+
+    private final String name;
+    private final String capital;
+
+}

core-java-modules/core-java-collections-list-5/src/test/java/com/baeldung/java/list/ListContainsElementFromOtherListTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.java.list;
+
+import static java.util.stream.Collectors.toSet;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.commons.collections4.CollectionUtils;
+import org.junit.Test;
+
+import com.baeldung.list.Country;
+
+public class ListContainsElementFromOtherListTest {
+
+    final private List<String> listOfLetters = Arrays.asList("a", "b", "c", "d");
+    final private List<String> listOfLettersWithOverlap = Arrays.asList("d", "e", "f", "g");
+    final private List<String> listOfCities = Arrays.asList("London", "Berlin", "Paris", "Brussels");
+
+    @Test
+    public void givenWholeValuesToCompare_whenUsingCollectionsDisjoint_thenDetectElementsInTwoLists() {
+        boolean shouldBeTrue = !Collections.disjoint(listOfLetters, listOfLettersWithOverlap);
+        assertTrue(shouldBeTrue);
+
+        boolean shouldBeFalse = !Collections.disjoint(listOfLetters, listOfCities);
+        assertFalse(shouldBeFalse);
+    }
+
+    @Test
+    public void givenWholeValuesToCompare_whenUsingStreams_thenDetectElementsInTwoLists() {
+        boolean shouldBeTrue = listOfLetters.stream()
+          .anyMatch(listOfLettersWithOverlap::contains);
+        assertTrue(shouldBeTrue);
+
+        boolean shouldBeFalse = listOfLetters.stream()
+          .anyMatch(listOfCities::contains);
+        assertFalse(shouldBeFalse);
+    }
+
+    @Test
+    public void givenWholeValuesToCompare_whenUsingApacheCollectionUtils_thenDetectElementsInTwoLists() {
+        boolean shouldBeTrue = CollectionUtils.containsAny(listOfLetters, listOfLettersWithOverlap);
+        assertTrue(shouldBeTrue);
+
+        boolean shouldBeFalse = CollectionUtils.containsAny(listOfLetters, listOfCities);
+        assertFalse(shouldBeFalse);
+    }
+
+    @Test
+    public void givenWholePorpertiesInObjectsToCompare_whenUsingStreams_thenDetectElementsInTwoLists() {
+        Country france = new Country("France", "Paris");
+        Country belgium = new Country("Belgium", "Brussels");
+        Country spain = new Country("Spain", "Madrid");
+        List<Country> franceAndBelgium = Arrays.asList(france, belgium);
+        List<Country> belgiumAndSpain = Arrays.asList(belgium, spain);
+
+        boolean shouldBeTrue = franceAndBelgium.stream()
+          .map(Country::getCapital)
+          .anyMatch(belgiumAndSpain.stream()
+            .map(Country::getCapital)
+            .collect(toSet())::contains);
+
+        assertTrue(shouldBeTrue);
+    }
+
+}