Passing in a sub-class to a method but having the super class as the parameter?

java, oop

Solution

Do this instead:

public <T extends Vehicle> void exampleMethod(Class<T> type) 

Problem

I have an abstract class `Vehicle` with 2 implemented subclasses `RedVehicle` and `YellowVehicle`. In another class I have a `List<Vehicle>` containing instances of both subclasses. I want to be able to pass into a method a class type and then use that type to decide which set of objects I want to do something to in the `List`. Since `Class` is generic I should parameterise it with something, however putting the parameter as the parent class `Vehicle` stops the calling code working since `exampleMethod` is now expecting a type of Vehicle, not a subclass of `RedVehicle` or `YellowVehicle`. I feel there should be a clean way to do this so what would be the correct way to implement the functionality? n.b. I don't necessarily have to pass in the `Class` type, if there are better suggestions I'd be happy to try those. Calling code: ``` service.exampleMethod(RedVehicle.class); service.exampleMethod(YellowVehicle.class); ``` Fields/Method: ``` //List of vehicles //Vehicle has 2 subclasses, RedVehicle and YellowVehicle private List<Vehicle> vehicles; //Having <Vehicle> as the Class parameter stops the calling code working public void exampleMethod(Class<Vehicle> type) { for(Vehicle v : vehicles) { if(v.getClass().equals(type)) { //do something } } } ```

Original source

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