List <String> diceColorsList = new ArrayList<String>(Arrays.asList("red", "blue", "green", "yellow", "white"));

   public String rollDiceColor(){
        Random rand = new Random();
        if (diceColorsList.size() > 0) {
            int n = rand.nextInt(diceColorsList.size());
            String str = diceColorsList.get(n);
            diceColorsList.remove(n);
            return str;
        } else {
            return "0";
        }
    }

    public int rollDiceNumber(){
        Random rand = new Random();
        int n = rand.nextInt(3)+1;
        return n;
    }

    public void resetDice(){
        diceColorsList = new ArrayList<String>(Arrays.asList("red", "blue", "green", "yellow", "white"));
    }