java deck shuffle

public class Deck {

    ArrayList<Card> deck;

    public static void suffleSystem(ArrayList<Card> deck)
    {
        Collections.shuffle(deck);
    }

    // TODO not forget seed it somewhere
    static Random random = new Random();
    public static void suffleManual(ArrayList<Card> deck)
    {
        int size = deck.size();
        for (int idx = 0; idx<deck.size(); idx++)
        {
            int chgIdx = idx + random.nextInt(size-idx);
            // swap here
            Card temp = deck.get(idx);
            deck.set(idx, deck.get(chgIdx));
            deck.set(chgIdx, temp);
        }
    }

}