Question

1Write a Java program that calculates and displays the Fibonacciseries, defined by the recursive formula

F(n) = F(n-1) + F(n-2).

F(0) and F(1) are given on the command line.Define and use a class Fib with the following structure:

public class Fib {

// constructorpublic Fib(int f0, int f1){.....}
// computes F(n) using an ***iterative*** algorithm, where F(n) = F(n-1) +

F(n-2) is the recursive definition.

// use instance variables that store F(0) and F(1).

// check parameter and throw exception if n < 0. Don't worry about

arithmetic overflow.

public int f(int n) {....}
// computes F(n) using the ***recursive*** algorithm, where F(n) = F(n-1)

+ F(n-2) is the recursive definition.

// use instance variables that store F(0) and F(1).// check parameter and throw exception if n < 0. Don't worry about

arithmetic overflow.

public int fRec(int n) {....}
public static void main(String[] args){

// get numbers F(0) and F(1) from args[0] and args[1].// use either the Scanner class or Integer.parseInt(args[...])// you must handle possible exceptions !....
// get n from args[2]:....
// create a Fib object with params F(0) and F(1)....
// calculate F(0), ..., F(n) and display them with

System.out.println(...) using

// the iterative methode f(i)....
// calculate F(0), ..., F(n) and display them with

System.out.println(...) using

// the recursive methode fRec(i)....

}
// instance variables store F(0) and F(1):....

};

Write javadoc comments for the Fib class.

Answer 1

// Fib.java

/**
* This class provide iterative as well as recursive mode of
* finding nth value of fibonaci series
*
* To run this program please run like java Fib 1 1 10
*
* This means f(0) = 1, f(1) = 1 and you want to compute series for 10 numbers
*
* @author Anonymous
*
*/
public class Fib {
   public Fib(int first, int second)
   {
       f0 = first;
       f1 = second;
   }
  
   static int f0;
   static int f1;
  
   public static int f(int n) throws Exception
   {
       if (n < 0)
       {
           throw new Exception ("invalid value: n should be greater than equal to 0");
       }
      
       if (n == 0) return f0;
       if (n == 1) return f1;          
      
       int prev = f1;
       int prevprev = f0;
       int result = 0;
       for (int i = 2 ; i <= n; i++)
       {
           result = prev + prevprev;
           prevprev = prev;
           prev = result;
       }
       return result;
   }

   public static int fRec(int n) throws Exception
   {
       if (n < 0)
       {
           throw new Exception ("invalid value: n should be greater than equal to 0");
       }
      
       if ( n == 0)
       {
           return f0;
       }
       if (n == 1)
       {
           return f1;
       }
      
       return fRec(n-1) + fRec(n-2);
   }

   public static void main(String[] args) throws Exception{
       int first = 0;
       int second = 0;
       int n = 0;
       try
       {
           first = Integer.parseInt(args[0]);
           second = Integer.parseInt(args[1]);
           n = Integer.parseInt(args[2]);
       }
       catch (Exception e)
       {
           System.out.println("Please enter integer number only: " + e);
           throw e;
       }
      
       Fib fib = new Fib(first, second);`
      
       System.out.println("Printing using iterative method");
       for (int i = 0; i <= n; i++)
       {
           System.out.println(f(i));
       }
      
       System.out.println("Printing using recursive method");
       for (int i = 0; i <= n; i++)
       {
           System.out.println(fRec(i));
       }
   }
};

/*

Sample run

java 1 1 30
Printing using iterative method
1
1
2
3
5
8
13
21
34
55
89
144
233
377
610
987
1597
2584
4181
6765
10946
17711
28657
46368
75025
121393
196418
317811
514229
832040
1346269
Printing using recursive method
1
1
2
3
5
8
13
21
34
55
89
144
233
377
610
987
1597
2584
4181
6765
10946
17711
28657
46368
75025
121393
196418
317811
514229
832040
1346269

*/