Let’s learn fibonacci series in java.

## Fibonacci series in java

A fibonacci series is a sequence where next number is sum of previous two numbers.

fibonacci sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21 . . . . .

Here’s algorithm for fibonacci series.

- Initially first two numbers in fibonacci series are fixed. That is, 0 and 1.
- Next number in the fibonacci series will be the sum of previous two numbers and so on. The fibonacci series continues.
- Now the logic here is first create two variables ‘a’ and ‘b’ having values 0 and 1. Also create variable int number.
- Then in the for loop iterate variable ‘i’ equal to one to ‘i’ less than or equal to 10 (for loop executing 10 times).
- now ‘number’ is equal to ‘a’ plus ‘b’. Meanwhile print ‘number’ on the console using System.out.println
- now assign value ‘b’ to ‘a’ and value ‘number’ to ‘b’. By doing this we are swapping values inside for loop.

Let’s see java program to display fibonacci series using for loop.

public class FibonacciSeriesForLoop { public static void main(String[] args) { int f = 10, num1 = 0, num2 = 1; System.out.print("First " + f + " fibonacci sequence: "); for(int a = 1; a <= f; ++a) { System.out.print(num1 + " + "); int total = num1 + num2; num1 = num2; num2 = total; } } }

**Output:**

First 10 fibonacci sequence: 0 + 1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 +

**fibonacci series using while loop**

In the same way we can use while loop to display fibonacci series.

Here’s the fibonacci series in java using while loop.

public class FibonacciSeriesWhileLoop { public static void main(String[] args) { int a = 1, num = 15, num1 = 0, num2 = 1; System.out.print("First " + num + " fibonacci sequence: "); while(a <= num) { System.out.print(num1 + " , "); int total = num1 + num2; num1 = num2; num2 = total; a++; } } }

**Output:**

First 15 fibonacci sequence: 0 , 1 , 1 , 2 , 3 , 5 , 8 , 13 , 21 , 34 , 55 , 89 , 144 , 233 , 377 ,

### fibonacci program using recursion

public class FibonacciRecursion { static intnum1= 0,num2= 1,num3= 0; public static void main(String[] args) { System.out.print(num1+ " " +num2); FibonacciRecursion obj = new FibonacciRecursion(); obj.fibonacciRecursive(14); } void fibonacciRecursive(int f) { if(f > 0) {num3=num1+num2; System.out.print(" " +num3);num1=num2;num2=num3; // fibonacci recursion fibonacciRecursive(f - 1); } } }

**Output:**

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610