Java Recursive Method: Calculate the nth Fibonacci number

Java Recursive: Exercise-3 with Solution

Write a Java recursive method to calculate the nth Fibonacci number.

Sample Solution:

Java Code:

public class FibonacciCalculator {

  public static int calculateFibonacci(int n) {
    // Base case: Fibonacci numbers at positions 0 and 1 are 0 and 1, respectively
    if (n == 0) {
      return 0;
    } else if (n == 1) {
      return 1;
    }

    // Recursive case: sum of the previous two Fibonacci numbers
    return calculateFibonacci(n - 1) + calculateFibonacci(n - 2);
  }

  public static void main(String[] args) {
    int position = 0;
    int fibonacciNumber = calculateFibonacci(position);
    System.out.println("The Fibonacci number at position " + position + " is: " + fibonacciNumber);
    position = 3;
    fibonacciNumber = calculateFibonacci(position);
    System.out.println("\nThe Fibonacci number at position " + position + " is: " + fibonacciNumber);
    position = 9;
    fibonacciNumber = calculateFibonacci(position);
    System.out.println("\nThe Fibonacci number at position " + position + " is: " + fibonacciNumber);
  }
}

Sample Output:

The Fibonacci number at position 0 is: 0

The Fibonacci number at position 3 is: 2

The Fibonacci number at position 9 is: 34

Explanation:

In the above exercises -

The "calculateFibonacci()" method follows the recursive definition of the Fibonacci sequence. It has two cases:

• case 1: If n is 0, it returns 0.
• case 2: If n is 1, it returns 1.

These are the termination conditions for recursion.

For any positive n greater than 1, the method recursively calculates the Fibonacci number by summing the previous two Fibonacci numbers (calculated using the same method). This process is repeated until n reaches one of the base cases.

In the main() method, we demonstrate the calculateFibonacci() method by calculating the Fibonacci number at position 8 and printing the result.

Flowchart:

Java Code Editor:

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