Sum of Digits

Easy
39
74.6% Acceptance

In this lab, you will develop a Java method named sumOfDigits. This method takes an integer as input and returns a single-digit integer by summing the digits repeatedly until only a single digit remains.

Method Specification

  • Method Name: sumOfDigits
  • Input: An integer (int).
  • Output: A single-digit integer (int).

Task

Your task is to implement the sumOfDigits method in the Main class. This method should continuously sum the digits of the input number until the sum is a single digit.

Edge Cases and Examples

  1. Single-Digit Input: If the input is already a single digit, the method should return the input itself.

    • Example: For input 5, the output should also be 5.

  2. Multi-Digit Input: For multi-digit inputs, the method should add up all the digits and, if the result is more than one digit, continue summing the digits of the result until a single digit is obtained.

    • Example: For input 129, the sum is 1 + 2 + 9 = 12. Since 12 is not a single digit, sum its digits: 1 + 2 = 3. The output should be 3.

Requirements

  • Implement the sumOfDigits method in a class named Main.
  • Ensure the method handles both single-digit and multi-digit inputs correctly.
  • Pay special attention to edge cases to ensure your method can handle any integer input within the bounds of the int data type.

This lab challenges your ability to write efficient and accurate Java code, focusing on iterative processing and condition handling. Good luck!

Challenges

Challenge 1: Validate Method Name and Return Type

Objective: Verify that the method is correctly named sumOfDigits and returns an int type.

  • Requirement: The method must be named sumOfDigits.
  • Return Type: The method should return an integer (int).
  • Details: Confirm the existence of the sumOfDigits method and ensure it is designed to return an int.

Challenge 2: Test Case for Single Digit Argument

Objective: Ensure the method correctly handles a single-digit input.

  • Input: A single-digit integer (e.g., 5).
  • Expected Behavior: The method should return the input itself, as the sum of a single-digit number is the number itself.
  • Details: Test the method with a single-digit input and expect the output to be identical to the input.

Challenge 3: Test Case for Double Digit Argument

Objective: Test the method with a double-digit input.

  • Input: A double-digit integer (e.g., 34).
  • Expected Behavior: The method should sum the digits and continue summing until a single digit is obtained.
  • Details: Provide a double-digit number and verify that the method correctly reduces it to a single digit.

Challenge 4: Test Case for Triple Digit Argument

Objective: Assess the method's handling of a triple-digit input.

  • Input: A triple-digit integer (e.g., 129).
  • Expected Behavior: The method should sum the digits and continue the process until a single digit is reached.
  • Details: Test the method with a triple-digit input and confirm it properly reduces it to a single digit.

Challenge 5: Test Case for Five Digit Argument

Objective: Evaluate the method's performance with a five-digit input.

  • Input: A five-digit integer (e.g., 54321).
  • Expected Behavior: The method should sum the digits iteratively until a single-digit sum is obtained.
  • Details: Input a five-digit number and check that the method accurately reduces it to a single digit.