Fibonacci Series

Number series in which next number is the sum of previous two numbers is called Fibonacci Series

Example : 0, 1, 1, 2, 3, 5, 8, 13, etc.

Fibonacci Series in Java can be written in following two ways :

1) Without Recursion
2) With Recursion

Following two programmes illustrate Fibonacci Series Using Recursion & without using Recursion

1) Java Program For Fibonacci Series Using Recursion

public class fibonacciRecMethod {

	 public static int fibonacciRecMeth(int count) {
		    if (count == 0) {
		      return 0;
		    } 

		    if (count == 1 || count == 2) {
		      return 1;
		    } 

		    return fibonacciRecMeth(count - 1) + fibonacciRecMeth(count - 2);
		  }

}

public class FibonacciRec {
  

  public static void main(String args[]) {
    int series_count = 9;

    System.out.print("Fibonacci Series For First " + series_count + " numbers is: \n");

    for (int i = 0; i < series_count; i++) {
      System.out.print(fibonacciRecMethod.fibonacciRecMeth(i) + " ");
    }
  }
}

Output :

Fibonacci Series For First 9 numbers is: 
0 1 1 2 3 5 8 13 21 

2) Java Program For Fibonacci Series Without Using Recursion

public class FibonacciWithoutRec {
   public static void main(String args[]) {
       int n1 = 0, n2 = 1, n3, i, series_count = 9;
	   System.out.print("Fibonacci Series For First " + series_count + " numbers is: \n");
       System.out.print(n1 + " " + n2);
       for (i = 2; i < series_count; ++i) {
          n3 = n1 + n2;
          System.out.print(" " + n3);
          n1 = n2;
          n2 = n3;
       }
    }
 }

Output :

Fibonacci Series For First 9 numbers is: 
0 1 1 2 3 5 8 13 21