Add Hamming Distance (#3164)

src/test/java/com/thealgorithms/strings/HammingDistanceTest.java

@@ -0,0 +1,23 @@
+package com.thealgorithms.strings;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class HammingDistanceTest {
+    @Test
+    void testHammingDistance() throws Exception {
+        assertEquals(HammingDistance.calculateHammingDistance("", ""), 0);
+        assertEquals(HammingDistance.calculateHammingDistance("java", "java"), 0);
+        assertEquals(HammingDistance.calculateHammingDistance("karolin", "kathrin"), 3);
+        assertEquals(HammingDistance.calculateHammingDistance("kathrin", "kerstin"), 4);
+        assertEquals(HammingDistance.calculateHammingDistance("00000", "11111"), 5);
+    }
+
+    @Test
+    void testNotEqualStringLengths() {
+        Exception exception = assertThrows(Exception.class, () -> HammingDistance.calculateHammingDistance("ab", "abc"));
+        assertEquals("String lengths must be equal", exception.getMessage());
+    }
+}