public EnemyWave(Enemy enemyPrototype, int nrOfEnemies, double groupActivationTime, double activationTime) {
         for (int i = 0; i < nrOfEnemies; i++) {
            double totalActivationTime = i*activationTime;
            enemiesInCurrentWave.add(i,new Enemy(enemyPrototype, totalActivationTime));
        }
        this.groupActivationTime = groupActivationTime;
            }