Jan-Benedikt Jagusch :
Let's assume I have 3 classes: Car, Convertible and Garage.
Car:
public class Car {
private String name;
private String color;
public Car(String name, String color) {
this.name = name;
this.color = color;
}
//Getters
}
Convertible inherits from Car:
public class Convertible extends Car{
private boolean roof;
public Convertible(String name, String color, boolean roof) {
super(name, color);
this.roof = roof;
}
public boolean isRoof() {
return roof;
}
}
Garage stores a list of Cars:
public class Garage {
private int capacity;
private List<Car> cars = new LinkedList<Car>();
//Setter for capacity
}
How could I create a subclass of Garage called ConvertibleGarage that can only store Convertibles?
Chris :
You could use a little bit of generics:
public class Garage<T extends Convertible> {
private int capacity;
private List<T> cars = new LinkedList<T>();
public Garage(int capacity) {
this.capacity = capacity;
}
}
This means when you instantiate a Garage you now have to include a parameter type that is a Convertible or child of it.
Garage<Convertible> cGarage = new Garage<>();
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