private void setPredictedWeapon(Weapon predictedWeapon) {
        if (predictedWeapon == null) {
            this.predictedWeapon = null;
        } else {
            switch (predictedWeapon) { 
                case ROCK:
                    this.predictedWeapon = Weapon.SCISSORS;
                    break;
                case PAPER:
                    this.predictedWeapon = Weapon.ROCK;
                    break;
                case SCISSORS:
                    this.predictedWeapon = Weapon.PAPER;
                    break;
            }
        }
    }