Doubt in inheritance exercise in C#

Question

I’m trying to solve an inheritance exercise and I found a question that I saw that you have a chance to show up in other places and so I thought I should ask here. The exercise asked to first create a class Voo which represents an aeroplane flight and is capable of handling seat occupancy information, part of which is that each flight has a maximum of 100 seats.

Then it is asked to create an heiress class that allows the definition of the number of maximum chairs and to split the plane into smokers and non-smokers. Regarding the part of smokers I know how to implement. What I don’t know is the variable number of chairs because of the way I implemented the base class.

As there are 100 seats, I created an array of 100 size bool in the base class in which the i-nth entry is true if the seat i is busy. I basically did this by initializing the array in the constructor as follows:

public class Voo
{
    private bool[] ocupacaoAssentos;

    public int Numero { get; private set; }

    public Data Data { get; private set; }

    public Voo(int numeroVoo, Data data)
    {
        this.Numero = numeroVoo;

        this.Data = data;

        this.ocupacaoAssentos = new bool[100];
    }
}

So the methods manipulate this array. The problem is that the class heiress would not have been able to modify this. As far as I know, in C# the heiress class constructor always calls the base class constructor.

A possible solution (in C#) would implement this with a collection class that does not have fixed size and then create a static readonly field that says the maximum of seats and then modify it in the heiress class and from there do checks so that everything stays within the limits. I don’t know if the exercise point would be valid, because the exercise is in Java and I don’t know if Java has these collection classes like C#.

But what if I couldn’t modify the base class for some reason or for some other detail of the problem I just couldn’t apply such a solution? How could I handle it? This is a case that seems to me that the base class is more general than the heiress class.

Answer 1

There are several ways to do this. One simple way is to create a new constructor that allows defining the number of seats:

public Voo(int numeroVoo, int numeroAssentos, Data data)
{
   ...
   this.ocupacaoAssentos = new bool[numeroAssentos];
   ...
}

In the heiress class invoke this new constructor using ":base()":

public ClasseHerdeira(int numeroVoo, int numeroAssentos, Data data)
{
   :base(numeroVoo, numeroAssentos, data) { }
}

Another way is to create a setNumerAssent() method in the Flight class and invoke this method in the heiress class constructor.

Answer 2

To access the inherited constructor use :base that you will access the class builders

The keyword base is used to access the members of the base class from within a derived class (Translation).

Reference: base (C# Reference)

Example

Base Class

public class Voo
{
    private bool[] ocupacaoassentos;
    public int Numero { get; private set; }
    public DateTime Data { get; private set; }

    public Voo()
    {
        this.Numero = 0;
        this.Data = DateTime.Now;
        this.ocupacaoassentos = new bool[100];
    }
    public Voo(int NumeroVoo, bool[] OcupacaoAssentos)
    {
        this.Numero = NumeroVoo;
        this.Data = DateTime.Now;
        this.ocupacaoassentos = OcupacaoAssentos;
    }
    public Voo(int NumeroVoo, DateTime Data, bool[] OcupacaoAssentos)
    {
        this.Numero = NumeroVoo;
        this.Data = Data;
        this.ocupacaoassentos = OcupacaoAssentos;
    }               
}

---

Derivative Class (Class Inheritance Flight)

public class HerdaVoo: Voo
{
    //Construtor sem paramentros igual classe base
    public HerdaVoo()
        :base() { }

    //Construtor com paramentro seguindo o construtor da classe base
    public HerdaVoo(int NumeroVoo, bool[] OcupacaoAssentos)
        : base(NumeroVoo, OcupacaoAssentos) { }

    //Construtor com paramentro seguindo o construtor da classe base
    public HerdaVoo(int NumeroVoo, DateTime Data, bool[] OcupacaoAssentos)
        :base(NumeroVoo, Data, OcupacaoAssentos) { }
}

Notice that it will access the 3 constructors of the base class note in the figure:

Coding

HerdaVoo herda = new HerdaVoo(100, DateTime.Now, new bool[500]);