public long getNewId(ProductList list) throws InvalidIdException {
		long id = 1;
		long count = 1;
		while(id < 999999 && count < list.size()){
			if(list.findProductById(id) != null){
				id++;
				count++;
			}
		}
		if (id < 1000000){
			return id;
		}	else {
			throw new InvalidIdException("Id-Limit erreicht!");
		}
	}