Add Hamming Distance (#3164)

src/main/java/com/thealgorithms/strings/HammingDistance.java

@@ -0,0 +1,32 @@
+package com.thealgorithms.strings;
+
+/* In information theory, the Hamming distance between two strings of equal length 
+is the number of positions at which the corresponding symbols are different. 
+https://en.wikipedia.org/wiki/Hamming_distance
+*/
+public class HammingDistance {
+
+    /**
+     * calculate the hamming distance between two strings of equal length
+     *
+     * @param s1 the first string
+     * @param s2 the second string
+     * @return {@code int} hamming distance
+     * @throws Exception
+     */
+    public static int calculateHammingDistance(String s1, String s2) throws Exception {
+        if (s1.length() != s2.length()) {
+            throw new Exception("String lengths must be equal");
+        }
+        
+        int stringLength = s1.length();
+        int counter = 0;
+        
+        for (int i = 0; i < stringLength; i++) {
+            if (s1.charAt(i) != s2.charAt(i)) {
+                counter++;
+            }
+        }
+        return counter;
+    }
+}