java - Parameterized Lists in method signature -

java - Parameterized Lists in method signature -

something next not give me compile-time or runtime error , i'm drawing blank why. there way enforce compile error on phone call cls.add?

why isn't definition of t in class definition beingness carried on phone call methods inside? understand didn't instantiate class way, definition of class states t must number.

public class newclass<t extends number> { private list<t> id = new arraylist<t>(); public void add(list<t> elem) { id.addall(elem); } public static void main(string[] args) { newclass cls = new newclass(); cls.add(new arraylist<string>()); } }

you using raw type. type info ignored in case, , warning.

if provide type parameter, fail:

newclass<integer> cls = new newclass<integer>(); cls.add(new arraylist<string>()); //error

java generics