如何从非父类调用抽象类

Question

I have a non abstract class called 'Player', and an abstract class called 'Score' with a subclass of 'Combination'. Within Combination there is and abstract method used in further subclasses.

How can I call my abstract method from the non-parent method 'Player' without making them static?

// This is the abstract method within Combination, 
// it uses the face values from rolled dice to calculate the score.

abstract public int CalculateScore(int[] faceValues);

//Array of 'Score's in Player

private Score[] scores = new Score[10];

Answer 1

You cannot. This is access modifier and it was designed to narrow access to a class. To use it in your case, I suggest to change accessibility from abstract to public of a Score class.

Answer 2

If I understand you correctly, you want to implement CalculateScore in your derived class by accessing the scores field?

Simple answer is, you can't as you designed it that way. private modifier makes sure, only your own class can access the field. If you want derived classes to have access to that field, you have to change your modifier to protected on the scores -field.

If you do not want your derived classes to have access to scores directly, you have to implement methods with at least protected access, that modify the scores -field in a defined way, on the base class.

Answer 3

So your situation:

• Player is a normal classs
• Score is an abstract class
• Combination is an abstract class too that subclasses Score . It contains an abstract method CalculateScore that you want to call from inside the Player class.
• Player has an array of Score s

You can check if an element in your Score array is of type Combination then cast it.

if(score[0] is Combination)
{
    (score[0] as Combination).CalculateScore(/* arguments here */);
}

You might need to rethink how your classes work though. IMHO, Player shouldn't be the one calculating the scores. Maybe use a ScoreCalculatorService to handle that.