Fibonacci Series in Java

Fibonacci Series in java is a series of increasing numbers where the first two terms are 0 and 1 respectively. All other subsequent terms are obtained by adding the last two terms before them.

Mathematically,

Let f(n) returns us the nth fibonacci number

$f(0)=0; f(1)=1;$

$f(n)=f(n-1)+f(n-2);$

Fibonacci Series in Java Introduction

There are several methods to write the Fibonacci series. In this article, we will discuss the following methods in detail:

Fibonacci Series in Java Using for Loop
Fibonacci Series in Java Using while Loop
Fibonacci Series in Java Using Iterative Approach
Fibonacci Series in Java Using recursion
Fibonacci Series in Java Using Dynamic Programming

Fibonacci Series in Java Using for Loop

Output:

Explanation:

The Java program calculates the nth number of the Fibonacci sequence, taking n as input from the user.

It initializes an integer array of size $n$ to store the Fibonacci sequence and uses a for loop to calculate the remaining elements. Finally, it prints the nth Fibonacci number to the console.

Time Complexity

O(N) - (Linear Time Complexity)

This is because, for finding the nth Fibonacci number, we move through an array of size n (actually, we are moving $n-2$ indices in the array).

Space Complexity

O(N)

Transform Your Career

Choose from our industry-leading programs designed for career success

NSDC Certified

Modern Software and AI Engineering Program

Master full-stack development with AI integration

12 MonthsDuration

AI-LedCurriculum

Career SupportSupport

+1000 more

Go to Program

NSDC Certified

Modern Data Science and ML with specialisation in AI

Advanced data science techniques with AI specialization

12 MonthsDuration

AI-LedCurriculum

Career SupportSupport

+1000 more

Go to Program

NSDC Certified

Advanced AIML with Specialisation in Agentic AI

Deep dive into AIML with focus on Agentic systems

12 MonthsDuration

AI-LedCurriculum

Career SupportSupport

+1000 more

Go to Program

NSDC Certified

DevOps, Cloud & AI Platform Engineering

Build and manage AI-powered cloud infrastructure

12 MonthsDuration

AI-LedCurriculum

Career SupportSupport

+1000 more

Go to Program

NSDC Certified

AI Engineering Advanced Certification by IIT-Roorkee

Premier AI engineering certification from IIT-Roorkee

3 MonthsDuration

AI-LedCurriculum

Career SupportSupport

Go to Program

Fibonacci Series in Java Using while Loop

Output:

Explanation:

The Java program calculates the nth number of the Fibonacci sequence using a while loop instead of a for loop.

It takes n as input from the user and initializes an integer array of size n to store the Fibonacci sequence. The loop condition i < n is used to calculate the remaining elements of the sequence. Finally, it prints the nth Fibonacci number to the console.

Time Complexity

O(N) - (Linear Time Complexity)

This is because, to find the nth Fibonacci number, we move through an array of size n (actually, we are moving n-2 indices in the array) using a while loop.

Space Complexity

O(N)

Fibonacci Series in Java Using Iterative Approach

Output:

Explanation: The above program generates and prints the Fibonacci series up to 15 terms using the previous two Fibonacci values iteratively.

Time Complexity

O(N) - (Linear Time Complexity)

Space Complexity

O(1)

Turn Learning into Career Growth

1200+Hiring Partners

89%Placement Rate

11,000+Placements

147%Avg Salary Increment

2.5XCareer Growth

₹23 LPAAvg Post-Scaler Salary

1200+Hiring Partners

89%Placement Rate

11,000+Placements

147%Avg Salary Increment

2.5XCareer Growth

₹23 LPAAvg Post-Scaler Salary

Fibonacci Series in Java Using recursion

The function returns the nth Fibonacci number by recursively calling itself for previous values until the input becomes less than or equal to 2. By calling this function to compute each Fibonacci number, we can print the Fibonacci series.

Output:

Explanation: In the above example, we defined a recursive function fib to get nth Fibonacci number and call it repeatedly (for i = 0 to i = 8) to create a Fibonacci series of length 9.

Read to know more about Fibonacci Series Using recursion in Java

Time Complexity

The Time Complexity is $O(2^n)$ , i.e. exponential time.

Space Complexity

O(1)

Join our expert-led Dynamic Programming Certification course to master advanced problem-solving techniques and enhance your programming prowess.

Scaler Placement Report and Statistics

₹23L

AVG CTC

SCALER PLACEMENT PROOF

Scaler learners achieved 2.5x salary growth with average post-Scaler CTC reaching ₹23L.

11,000+placements

650+companies

Verified data

See full placement report

Fibonacci Series in Java Using Dynamic Programming

Output:

Explanation: In the above program, we use the tabulation method of dynamic programming to calculate the Fibonacci series. It stores the value of the Fibonacci term in the array and calculates further values using the previous two values.

Time Complexity

O(N)

Space Complexity

O(N)

Conclusion

The Fibonacci Series in java is a sequence of numbers in which each number (except the first two) is the sum of the two preceding numbers.

The recursive approach uses a function that calls itself to calculate the Fibonacci numbers. It typically has a base case for the first two numbers and recursively computes subsequent numbers.
The time complexity of the recursive approach is exponential, specifically &O(2^n)&, due to repeated function calls and redundant calculations.
The iterative approach has a linear time complexity of O(n), where n is the desired number in the Fibonacci Series.