Java class generics

Question

What are my options, if I what the following code to work?

class Garage<X>{}

class Vehicle {}

class Car extends Vehicle {}

class Bike extends Vehicle {}

class A {
    public static void main(String[] args) {
        Garage<Car> car = new Garage<>();
        Garage<Bike> bike = new Garage<>();
        Garage<Vehicle> vehicle = new Garage<>();
        //what are the options to do this?
        vehicle=car;
        vehicle=bike;
    }
}

What I'm after is to try upcast(?) car and bike to vehicle. Is this even possible with this kind generic class type?

the whole reason for using generics is do you don't have to cast. If you find yourself casting you're doing it wrong — Nathan Hughes, Aug 26 '17 at 14:46

score 1 · Answer 1 · answered Aug 26 '17 at 14:37

1

In order to do what you desire, you need to change

Garage<Vehicle> vehicle = new Garage<>();

to

Garage<? extends Vehicle> vehicle = new Garage<>();

answered Aug 26 '17 at 14:37

Naman

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Java class generics

1 Answers1