(Fibonacci numbers) Rewrite the fib method in Listing 18.2 using iterations

/*********************************************************************************
* (Fibonacci numbers) Rewrite the fib method in Listing 18.2 using iterations.   *
* Hint: To compute fib(n) without recursion, you need to obtain fib(n - 2) and   *
* fib(n - 1) first. Let f0 and f1 denote the two previous Fibonacci numbers. The *
* current Fibonacci number would then be f0 + f1. The algorithm  can be          *
* described as follows:                                                          *
*                                                                                *
* f0 = 0; // For fib(0)                                                          *
* f1 = 1; // For fib(1)                                                          *
*                                                                                *
* for (int i = 1; i <= n; i++) {                                                 *
* 		currentFib = f0 + f1;                                                      *
* 		f0 = f1;                                                                   *
* 		f1 = currentFib;                                                           *
* }                                                                              *
* // After the loop, currentFib is fib(n)                                        *
*                                                                                *
* Write a test program that prompts the user to enter an index and displays its  *
* Fibonacci number.                                                              *
*********************************************************************************/
import java.util.Scanner;

public class Exercise_18_02 {
	/** Main method */
	public static void main(String[] args) {
		// Create a Scanner
		Scanner input = new Scanner(System.in);

		// Prompt the user to enter an index
		System.out.print("Enter an index for a Fibonacci number: ");
		int index = input.nextInt();

		// Find and display the Fibonacci number
		System.out.println("The Fibonacci number at index " 
			+ index + " is " + fib(index));

	}

	/** The method for finding the Fibonacci number */
	public static long fib(long index) {
		long f0 = 0; // For fib(0)         
		long f1 = 1; // For fib(1)
		long currentFib = 0;  

		if (index == 0)
			return f0;
		else if (index == 1)
			return f1;       
      else {
			for (int i = 1; i < index; i++) {
				currentFib = f0 + f1;     
				f0 = f1;                  
				f1 = currentFib;          
			} 
			return currentFib;                            
      }                       
	}
}