Even Fib

EulerModel.java

import java.util.Arrays;
import java.util.List;

public class EulerModel {
    public int sumSquareDifference(List<Integer> nums) {
        int sum = 0;
        int sumOfSquares = 0;
        for (int i : nums) {
            sum += i;
            sumOfSquares += (i * i);
        }
        return (sum * sum) - sumOfSquares;
    }

    public int sumSquareDifference(Integer... nums) {
        return sumSquareDifference(Arrays.asList(nums));
    }
    
    public int evenFib() {
        boolean notTooBig = true;
        int sum = 0;
        int a = 1;
        int b = 0;
        int x = 1;
        while (notTooBig) {
            x = a + b;
            b = a;
            a = x;
            if (x <= 4000000) {
                if (x % 2 == 0) {
                    sum += x;
                }
            } else {
                notTooBig = false;
            }
        }
        return sum;
    }
    
    public int evenFib(int threshold) {
        int first = 2;
        int second = 1;
        int sum = 0;
        int temp;
        
        while (first <= threshold) {
            if (first % 2 == 0) {
                sum += first;
            }            
            temp = first + second;
            second = first;
            first = temp;
        }
        
        return sum;
    }
}