Calculate Fibonacci Series in Java

Carvia Tech | April 30, 2019 | 1 min read | 58 views

Fibonacci series is series of natural number where next number is equivalent to the sum of previous two number e.g.

Fibonacci Series
fn = fn-1 + fn-2.

The first two numbers of Fibonacci series is always 1, 1.

First 10 numbers in fibonacci series are:

1 1 2 3 5 8 13 21 34 55

Iterative approach

Java program to calculate and print Fibonacci number using Iterations logic is shown below:

Basically on each iteration, we are assigning second number to the first and assigning the sum of last two numbers to the second.

Fibonacci using Iteration
void fibonacci(int count) {
    int prevNumber = 0;
    int nextNumber = 1;

    System.out.println("Fibonacci Series " + count + ":");
    for (int i = 1; i <= count; ++i) {
        int fib = prevNumber + nextNumber;
        prevNumber = nextNumber;
        nextNumber = fib;
        System.out.print(prevNumber + " ");

Recursive approach

We can use tail recursion to calculate fibonacci series in Java.

Tail recursion

A tail recursion is a recursive function where the function calls itself at the end ("tail") of the function in which no computation is done after the return of recursive call.

fibonacci series using Recursion
int fibonacci(int num) {
    if (num == 1 || num == 2) {
        return 1;   (1)
    return fibonacci(num - 1) + fibonacci(num - 2); (2)
1 Terminating condition for recursive function
2 Tail recursion where we are essentially calculating fn = fn-1 + fn-2

Top articles in this category:
  1. Top 50 SDET Java Programming Interview Questions & Answers
  2. SDET: JUnit interview questions for automation engineer
  3. Calculate factorial of a number in Java using recursion
  4. Commonly used Http methods in RESTful services
  5. Check if the given number is Armstrong Number in Java
  6. Write a program to reverse a string using recursion in Java
  7. Write a program to reverse the order of words in a string

Find more on this topic:
SDET Interviews image
SDET Interviews

SDET Java Interview pattern and collection of questions covering SDET coding challenges, automation testing concepts, functional, api, integration, performance and security testing, junit5, testng, jmeter, selenium and rest assured

Last updated 1 week ago

Recommended books for interview preparation:

This website uses cookies to ensure you get the best experience on our website. more info