public static Random random = new Random();

    public static int random(int from, int to) {
        return random.nextInt(to + 1) + from;
    }

    public static int roll(int[] indexes, double[] rates) {
        double sum = 0;
        for (int index : indexes) {
            sum += rates[index];
        }

        double t = 0;
        double[] percent = new double[indexes.length];

        for (int i = 0; i < indexes.length; i++) {
            int index = indexes[i];
            if (index < 0 || index >= rates.length) continue;
            t += rates[i] / sum;
            percent[i] = t;
        }

        double r = random.nextDouble();
        for (int i = 0; i < indexes.length; i++) {
            if (r <= percent[i]) {
                return i;
            }
        }

        return -1;
    }