Question

Here is an abstract example of my problem: I have a general class (Car) which has a type (brand). All objects should only differ by brand, and based on this brand should be handled differently.

All objects of this class are collected in a List of a Service class. The service should perform a routine on the whole list, which is mostly the same. Just one function call in between should differ.

Based on this type I want to call different methods: At the moment I’m asserting equals for the enum type and call different methods based on the outcome. But this is kind of ugly and I wonder if there are better solutions on this?

class Car {
    public enum Brand {
        BMW, AUDI;
    }

    private Brand brand;

    specificMeth1();
    specificMeth2();
}


class Service {

    List<Car> bmw;
    List<Car> Audi;

    processCar() {
        processList(bmw);
        processList(audi);
    }

    processList(List<Car> list) {
        for (Car car : list) {
            if (car.getBrand.equals(Brand.BMW)) {
                specificMeth1();
            } else {
                specificMeth2();
            }
        }
    }
}

Answer 1

You should put the method in the enum:

public enum Brand {
    BMW {
        @Override
        public void doSomething();
    },
    AUDI {
        @Override
        public void doSomething();
    };

    public abstract void doSomething();
}

var.getBrand().doSomething();