Change project structure to a Maven Java project + Refactor (#2816)

src/main/java/com/thealgorithms/maths/HarshadNumber.java

@@ -0,0 +1,57 @@
+// Wikipedia for Harshad Number : https://en.wikipedia.org/wiki/Harshad_number
+package com.thealgorithms.maths;
+
+import java.util.Scanner;
+
+public class HarshadNumber {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter a number : ");
+        long a = sc.nextLong();
+
+        checkHarshadNumber(a);
+    }
+
+    /**
+     * A function to check if a number is Harshad number or not
+     *
+     * @param a The number which should be checked
+     */
+    public static void checkHarshadNumber(long a) {
+
+        long b = a;
+        int sum = 0;
+
+        // this is just for showing the explanation else it's of no use you can ommit it
+        int[] each = new int[Long.toString(a).length()];
+
+        int c = 0;
+
+        while (b > 0) {
+            sum += b % 10;
+            each[c] = (int) (b % 10);
+            b /= 10;
+            c++;
+        }
+
+        if (a % sum == 0) {
+            System.out.println(a + " is a Harshad Number");
+
+            // For you better explanation how is that a Harshad Number
+            System.out.println("\nExplaination :");
+
+            for (int i = each.length - 1; i >= 0; i--) {
+                System.out.print(each[i] + " ");
+                if (i != 0) {
+                    System.out.print("+ ");
+                }
+            }
+
+            System.out.println("= " + sum);
+            System.out.println(sum + " × " + (a / sum) + " = " + a);
+        } else {
+            System.out.println(a + " is not a Harshad Number");
+        }
+    }
+}