Add Happy Number Detector

HappyNumber.java

@@ -0,0 +1,60 @@
+import java.util.Scanner;
+
+/*
+ * A happy number is a number that, when you repeatedly replace it with the sum of the square of its digits,
+ * eventually reaches 1.
+ * Example: 19 is a happy number because 1^2 + 9^2 = 82, and 8^2 + 2^2 = 68, and so on until it reaches 1.
+ */
+public class HappyNumber {
+    public static void main(String[] args) {
+        // Initialize the scanner class to take input
+        Scanner scanner = new Scanner(System.in);
+
+        // Prompt the user for input
+        System.out.print("Enter a number to check if it's a Happy Number: ");
+
+        // Take input
+        int number = scanner.nextInt();
+
+        // Check if the number is a Happy Number and print the desired message
+        if (isHappy(number)) {
+            System.out.println(number + " is a Happy Number.");
+        } else {
+            System.out.println(number + " is not a Happy Number.");
+        }
+    }
+
+    /**
+     * Checks if a given integer is a Happy Number.
+     *
+     * @param number the number to check.
+     * @return true if the input number is a Happy Number, false otherwise.
+     */
+    public static boolean isHappy(int number) {
+        // Initialize the sum of squared digits to 0.
+        int sum = 0;
+
+        // Iterate until n becomes 0.
+        while (number > 0) {
+            // Extract the last digit.
+            int temp = number % 10;
+
+            // Square and add the digit to the sum.
+            sum += (int) Math.pow(temp, 2);
+
+            // Remove the last digit by integer division.
+            number /= 10;
+        }
+
+        // Check if the sum of squared digits is 1, indicating a Happy Number.
+        if (sum == 1) {
+            return true;
+        } else if (sum == 4) {
+            // If the sum becomes 4, it will never reach 1, so it's not a Happy Number.
+            return false;
+        } else {
+            // Recursively call isHappy with the sum until we reach either 1 or 4.
+            return isHappy(sum);
+        }
+    }
+}