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 series : 0, 1, 1, 2, 3, 5, 8, 13, 21 . . . . .

Let’s see program for fibonacci series in java.

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 +

In the above java program,

- 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.

**Fibonacci program 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 series 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