A simple program for performing the fibonacci sequence.

App.java

package fib;

import java.util.Scanner;

public class App {

	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner stdIn = new java.util.Scanner(System.in);
		while (true) {
			try {
				System.out.print("Enter a number thats greater or equal to 0: ");
				int number = stdIn.nextInt();
				int result = fib(number);
				System.out.println("Result: " + result);
			} catch (Exception e) {
				System.out.println("Error: " + e.getMessage());
			}
		}
	}
	
	@SuppressWarnings("unused")
	private static int fib(int value) throws Exception {
		if (value < 0) throw new Exception("Value out of range.");
		
		if (value == 0 || value == 1) {
			return 1;
		} else {
			return fib(value - 1) + fib(value - 2);
		}
	}

}