Fibonacci Series Solution

Computer Science
1

My solution:

    public ArrayList<Integer> fibonacci(int firstN) {
        int a = 0;
        int b = 1;
        ArrayList<Integer> fibonacci = new ArrayList<Integer>();
        for (int i = 0; i < firstN; i++) {
            fibonacci.add(a);
            int temp = a;
            a = b;
            b = a + temp;
        }
        return fibonacci;
    }