Fibonacci Series in Java

The Fibonacci Series is a number series where each consecutive number is the sum of the previous two numbers. The Fibonacci Series in Java always begins with 0 and 1, which are added to produce the third number, which is then added to the second, and this mathematical operation reiterates infinitely. 

The Fibonacci Series is significantly used for determining the greatest common divisor of two integers. This series is a sequence where the number is the sum of the previous two numbers. In this blog, you'll learn how to display the Fibonacci Series in Java.

Table of Contents

1) Understanding the Fibonacci Series in Java

2) Implementing the Fibonacci Series in Java

   a) Using For Loop

   b) Using While Loop

   c) Using the user input

   d) Using Recursion

3) Conclusion

Understanding the Fibonacci Series in Java

In Fibonacci Series, two numbers are added to produce a third number, which is then added to the second, and this mathematical operation reiterates itself infinitely. It is a number series where each consecutive number is the sum of the previous two numbers.

The Fibonacci Series: 0,1,1,2,3,5,8,13,21, etc.

0 and 1 are the first two values to begin the arithmetic operation of addition, reiterated and proceeds to infinity.


 

Implementing the Fibonacci Series in Java

There are different ways to implement the Fibonacci Series in Java, such as using For Loop, While Loop, User Input, or Recursion. Here is a brief explanation of each method:

Using  For Loop

This method uses a For Loop to iterate from 1 to n, where n is the number of terms to be printed. In each iteration, the next term is calculated by adding the previous two terms, and the values of the previous two terms are updated accordingly. This method has a time complexity of:

                                                                       O(n)

And a space complexity of:

                                                                      O(1)

Here is an example code using For Loop:
 

Implementing the Fibonacci Series in Java

Using the For Loop

class Main
{ public static void main(String[] args)
{
int n = 10, firstTerm = 0, secondTerm = 1;
System.out.println("Fibonacci Series till " + n + " terms:");
for (int i = 1; i <= n; ++i)
{
System.out.print(firstTerm + ", ");
// compute the next term
int nextTerm = firstTerm + secondTerm;
firstTerm = secondTerm;
secondTerm = nextTerm;
}
}
}

Using the While Loop

This method uses a While Loop to iterate until a certain condition is met, such as the number of terms printed or the value of the current term. In each iteration, the next term is calculated by adding the previous two terms, and the values of the previous two terms are updated accordingly. This method has the same time and space complexity as the fFor Loop method. Here is an example code using While Loop:

//Using the While Loop
class Main
{
public static void main(String[] args)
{
int i = 1, n = 10, firstTerm = 0, secondTerm = 1;
System.out.println("Fibonacci Series till " + n + " terms:");
while (i <= n)
{
System.out.print(firstTerm + ", ");
int nextTerm = firstTerm + secondTerm;
firstTerm = secondTerm;
secondTerm = nextTerm;
i++;
}
}
}

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Using User Input

This method uses the Scanner class to get the input from the user, such as the number of terms to be printed or the limit of the series. The input is then used to control the loop condition, and the rest of the logic is similar to the previous methods. Here is an example code using User Input:

import java.util.*;
public class THKFibbonaci
{
public static void main(String[] args)
{
//Syntax to take input value from user
//Declare the Scanner class instance
Scanner sc=new Scanner(System.in);
int t1 = 0, t2 = 1;
System.out.print("Number of terms to be printed here: ");
int n=sc.nextInt();
//Here you you will declare how many terms yournseries will have
System.out.println("The First " + n + " terms of fibonnaci series: ");
//Print statement to get your Fibbonaci series
for (int i = 1; i <= n; ++i)
{ System.out.print(t1 + " ");
int total = t1 + t2;
t1 = t2;
t2 = total;
}
}
}

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Using Recursion

This method uses a Recursive Function to calculate the nth term of the Fibonacci series, where n is the input parameter. The Recursive Function calls itself with smaller values of n until it reaches the base case, which is n=0 or n=1, and then returns the value of n. The Recursive Function has a time complexity of: 

                                                     O(2n)

And a space complexity of: 

                                                    O(n)

Which are much higher than the Loop methods. Here is an example code using Recursion:
 

public class Fibonacci
{
public static void main(String[] args)
{
int n = 10; // number of terms to generate
System.out.print("Fibonacci series up to " + n + " terms: ");
for (int i = 0; i < n; i++)
{
System.out.print(fibonacci(i) + " ");
}
}
public static int fibonacci(int n)
{
if (n == 0)
{
return 0;
} else if (n == 1)
{
return 1;
}
else {
return fibonacci(n-1) + fibonacci(n-2);
}
}
}

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Conclusion

The Fibonacci Series in Java is a sequence extending to infinity, using a mathematical operation reiterating the addition of every two consecutive numbers. This blog has introduced you to the different Java programming logical structures which generate the Fibonacci Series in Java. These techniques include the For Loop, the While Loop, User input-based and Recursion.

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