Project Euler > Problem 2 > Even Fibonacci numbers (Java Solution)

Problem:

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

Solution:

4613732

Code:
The solution may include methods that will be found here: Library.java .

public interface EulerSolution{

public String run();

}

/* 
 * Solution to Project Euler problem 2
 * By Nayuki Minase
 * 
 * http://nayuki.eigenstate.org/page/project-euler-solutions
 * https://github.com/nayuki/Project-Euler-solutions
 */


public final class p002 implements EulerSolution {
 
 public static void main(String[] args) {
  System.out.println(new p002().run());
 }
 
 
 public String run() {
  int sum = 0;
  for (int i = 0; ; i++) {
   int fib = fibonacci(i);
   if (fib > 4000000)
    break;
   if (fib % 2 == 0)
    sum += fib;
  }
  return Integer.toString(sum);
 }
 
 
 private static int fibonacci(int x) {
  if (x < 0 || x > 46)
   throw new IllegalArgumentException();
  int a = 0;
  int b = 1;
  for (int i = 0; i < x; i++) {
   int c = a + b;
   a = b;
   b = c;
  }
  return a;
 }
 
}