Type checking an init method

Newbie & Debugging Questions
#1

Hello Java Gaming world! I have a question about type checking. So let me describe my situation.

I have this interface


public interface State<T extends Entity> {
	
	public void init(T t);
	
	public void update();
	
	public void render(Screen s);
	
	public void processCollision(T t);
	
	public T getEntity();
}

And this class:

public abstract class MobState<T extends Mob> implements State<Mob> {

	protected T m = null;
	
   // more fields defined here...
	
	// some methods defined here...
}

In my code, Mob extends Entity, and MobState implements State. Ball extends Mob, and BallNormalState extends MobState:


public class BallNormalState extends MobState<Ball> {
			
	public void init(Mob m) {
		this.m = (Ball) m;
	}
	
	// more methods defined here...
}

My question is, in BallNormalState::init, I can’t pass anything more specific than Mob because of the interface, so how can I best enforce type checking? It needs to be Ball and not any other type of Mob! Thanks for any advice! 8)