Consider this example (typical in OOP books):
I have an Animal class, where each Animal can have many friends.
And subclasses like Dog, Duck, Mouse etc which add specific behavior like bark(), quack() etc.
Here's the Animal class:
public class Animal {
private Map<String,Animal> friends = new HashMap<>();
public void addFriend(String name, Animal animal){
friends.put(name,animal);
}
public Animal callFriend(String name){
return friends.get(name);
}
}
And here's some code snippet with lots of typecasting:
Mouse jerry = new Mouse();
jerry.addFriend("spike", new Dog());
jerry.addFriend("quacker", new Duck());
((Dog) jerry.callFriend("spike")).bark();
((Duck) jerry.callFriend("quacker")).quack();
Is there any way I can use generics for the return type to get rid of the typecasting, so that I can say
jerry.callFriend("spike").bark();
jerry.callFriend("quacker").quack();
Here's some initial code with return type conveyed to the method as a parameter that's never used.
public<T extends Animal> T callFriend(String name, T unusedTypeObj){
return (T)friends.get(name);
}
Is there a way to figure out the return type at runtime without the extra parameter using instanceof? Or at least by passing a class of the type instead of a dummy instance.
I understand generics are for compile time type-checking, but is there a workaround for this?