Java Recursive Method: Calculate the sum of numbers from 1 to n

Java Recursive: Exercise-2 with Solution

Write a Java recursive method to calculate the sum of all numbers from 1 to n.

Sample Solution:

Java Code:

public class SumCalculator {

  public static int calculateSum(int n) {
    // Base case: sum of 0 is 0
    if (n == 0) {
      return 0;
    }

    // Recursive case: add n with the sum of (n-1)
    return n + calculateSum(n - 1);
  }

  public static void main(String[] args) {
    int number = 7;
    int sum = calculateSum(number);
    System.out.println("Sum of numbers from 1 to " + number + " is: " + sum);
  }
}

Sample Output:

Sum of numbers from 1 to 7 is: 28

Explanation:

In the above exercises -

The calculateSum() method follows the recursive definition of the sum. It has two cases:

• Base case: If the input n is 0, it returns 0. This is the termination condition for recursion.
• Recursive case: For any positive n, it adds n with the sum of the numbers from 1 to n-1. This step is repeated recursively until n reaches 0

In the main() method, we demonstrate the calculateSum() method by calculating the sum of numbers from 1 to 7 and printing the result.

Flowchart:

Java Code Editor:

Java Recursive Previous: Calculate the factorial of a number.
Java Recursive Next: Calculate the nth Fibonacci number.