Fibonacci series is numerical series in which next number is sum of previous two numbers.

For example :

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 etc.

There are two ways to print Fibonacci series.

For example :

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 etc.

There are two ways to print Fibonacci series.

- Using iteration
- Using recursion

### Using iteration:

#### Algorithm:

- Initialise first two terms with 0 and 1
- Find sum of first two terms.
- Iterate upto numberOfElements
- Print the sum
- Assign prev to next and next to sum to go for next two terms.

#### Program:

package org.arpit.java2blog.algo; public class FibonnacciIterativeMain { public static void main(String[] args) { System.out.println("Printing Fibonacci series:"); // first two number of series int prev=0,next=1; //printing first two elements System.out.print(prev+" "+next); //number of elements to be printed int numberOfElements=10; int sum=0; for(int i=2;i<numberOfElements;i++) { sum=prev+next; System.out.print(" "+sum); prev=next; next=sum; } } }When you run above program, you will get following output:

Printing Fibonacci series: 0 1 1 2 3 5 8 13 21 34

### Using recursion:

#### Algorithm:

- Initialise first two terms with 0 and 1
- Base case will be when numberOfElements becomes 0.
- Find sum of first two terms.
- Print the sum
- Assign prev to next and next to sum to go for next two terms.
- Call same function again and decrease numberOfElements.

#### Program:

package org.arpit.java2blog.algo; public class FibonnacciRecursionMain { //First two number of series static int prev=0,next=1; static int sum=0; public static void main(String[] args) { System.out.println("Printing Fibonacci series:"); //printing first two elements System.out.print(prev+" "+next); //number of elements to be printed int numberOfElements=10; // -2 because we have already printed 2 elements printFibonacciSeriers(numberOfElements-2); } public static void printFibonacciSeriers(int numberOfElements) { if(numberOfElements==0) return; else { sum=prev+next; System.out.print(" "+sum); //prepare for next 2 terms prev=next; next=sum; printFibonacciSeriers(numberOfElements-1); } } }When you run above program, you will get following output:

Printing Fibonacci series: 0 1 1 2 3 5 8 13 21 34

Please go through java interview programs for more such programs.