diff --git a/src/main/java/com/thealgorithms/strings/CheckVowels.java b/src/main/java/com/thealgorithms/strings/CheckVowels.java
index 44965cc9..21b536b5 100644
--- a/src/main/java/com/thealgorithms/strings/CheckVowels.java
+++ b/src/main/java/com/thealgorithms/strings/CheckVowels.java
@@ -1,7 +1,5 @@
 package com.thealgorithms.strings;
 
-import java.util.Arrays;
-import java.util.HashSet;
 import java.util.Set;
 
 /**
@@ -10,24 +8,24 @@ import java.util.Set;
  * alphabet. Wikipedia: https://en.wikipedia.org/wiki/Alphabetical_order
  */
 public final class CheckVowels {
+    private static final Set<Character> VOWELS = Set.of('a', 'e', 'i', 'o', 'u');
+
     private CheckVowels() {
     }
 
-    private static final Set<Character> VOWELS = new HashSet<>(Arrays.asList('a', 'e', 'i', 'o', 'u'));
-
     /**
-     * Check if a string is has vowels or not
+     * Checks if a string contains any vowels.
      *
-     * @param input a string
-     * @return {@code true} if given string has vowels, otherwise {@code false}
+     * @param input a string to check
+     * @return {@code true} if the given string contains at least one vowel, otherwise {@code false}
      */
     public static boolean hasVowels(String input) {
-        if (input == null) {
+        if (input == null || input.isEmpty()) {
             return false;
         }
-        input = input.toLowerCase();
-        for (int i = 0; i < input.length(); i++) {
-            if (VOWELS.contains(input.charAt(i))) {
+
+        for (char c : input.toLowerCase().toCharArray()) {
+            if (VOWELS.contains(c)) {
                 return true;
             }
         }
diff --git a/src/test/java/com/thealgorithms/strings/CheckVowelsTest.java b/src/test/java/com/thealgorithms/strings/CheckVowelsTest.java
index 713b53f0..ba510aa8 100644
--- a/src/test/java/com/thealgorithms/strings/CheckVowelsTest.java
+++ b/src/test/java/com/thealgorithms/strings/CheckVowelsTest.java
@@ -1,17 +1,15 @@
 package com.thealgorithms.strings;
 
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
-public class CheckVowelsTest {
+class CheckVowelsTest {
 
-    @Test
-    public void isVowel() {
-        assertTrue(CheckVowels.hasVowels("foo"));
-        assertTrue(CheckVowels.hasVowels("bar"));
-        assertFalse(CheckVowels.hasVowels("why"));
-        assertFalse(CheckVowels.hasVowels("myths"));
+    @ParameterizedTest
+    @CsvSource({"'foo', true", "'bar', true", "'why', false", "'myths', false", "'', false", "'AEIOU', true", "'bcdfghjklmnpqrstvwxyz', false", "'AeIoU', true"})
+    void testHasVowels(String input, boolean expected) {
+        assertEquals(CheckVowels.hasVowels(input), expected);
     }
 }