Question

I like to realize the following scenario. (example)

I have 3 Classes:

1. Controller
2. Apple
3. Car

public class Apple implements IBonus {
    public String name;
    public String weight;
}


public class Car implements IBonus{
    public String brand;
    public String vmax;
    public String power;
}

public class Controller {
    public List<String> values;

    public void doWork(IBonus bonusObject){
       if(bonusObject instanceOf Car){
          Car c = (Car)bonusObject;
          values.add(c.brand);
          values.add(c.vmax);
          values.add(c.power);
       }
       if(bonusObject instanceOf Apple){
          Apple a = (Apple)bonusObject;
          values.add(a.name);
          values.add(a.weight);
       }
    }
}

Now, I have a lot of Classes like apple and car. And there is also the possibility that some variables of each class will be changed, added or removed in the near future.
This will mean that I always have to adjust the code in the controller class.

Does anyone know a suitable pattern?

Answer 1

You don’t need any pattern for this. Just plain old polymorphism:

public interface IBonus {
    void fillStringList(List<String> values);
}
...

public void doWork(IBonus bonusObject){
   bonusObject.fillStringList(values);
}