Question

I need advice on interfaces. I have a class called Unit which can attack other units. The attack can be air or ground. I need single method to achieve attacking called attack(). Some units can only attack ground units, some air units or both.

This is what I’ve come up so far:

public interface Attack() {
    public void attack(SCObject object);
}

public interface GroundAttack() extends Attack {
    public void groundAttack(SCObject object);
}

public interface AirAttack() extends Attack {
    public void airAttack(SCObject object);
}

I have can have different units:

Unit extends SCObject implements GroundAttack {
}

Unit extends SCObject implements AirAttack {
}

Unit extends SCObject implements AirAttack, GroundAttack {
}

The problem is this implementation will reveal the two ground and air options whereas I only want attack() method to be visible.
Can you propose solution or does this seem ok to you?

Answer 1

I would use

public interface Attack {
    public boolean canAttack(SCObject object);
    public void attack(SCObject object);
}

I don’t see a reason to have a specific ground or air attack method given you didn’t want to expose this behaviour.