[unique-elements-list] Get Unique Values From an ArrayList In Java (#14152)

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

@@ -0,0 +1,41 @@
+package com.baeldung.java.uniqueelements;
+
+import static java.util.stream.Collectors.toList;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class UniqueElementsInListUnitTest {
+    // @formatter:off
+    private static final List<String> MY_LIST = Arrays.asList(new String[]{
+      "Microsoft Windows",
+      "Mac OS",
+      "GNU Linux",
+      "Free BSD",
+      "GNU Linux",
+      "Mac OS"});
+    // @formatter:on
+
+    @Test
+    void whenConvertToSet_thenGetExpectedResult() {
+        List<String> result = new ArrayList<>(new HashSet<>(MY_LIST));
+        assertThat(result).containsExactlyInAnyOrder("Free BSD", "Microsoft Windows", "Mac OS", "GNU Linux");
+
+        result = new ArrayList<>(new LinkedHashSet<>(MY_LIST));
+        assertThat(result).containsExactly("Microsoft Windows", "Mac OS", "GNU Linux", "Free BSD");
+    }
+
+    @Test
+    void whenUsingStream_thenGetExpectedResult() {
+        List<String> result = MY_LIST.stream()
+          .distinct()
+          .collect(toList());
+        assertThat(result).containsExactly("Microsoft Windows", "Mac OS", "GNU Linux", "Free BSD");
+    }
+}