Java generics - The type parameter String is hiding the type String

Question

In my interface:

public  Result query(T query)

In my 1st subclass:

public  Result query(HashMap que         


        

Answer 1

It thinks you're trying to create a type parameter -- a variable -- whose name is String. I suspect your first subclass simply doesn't import java.util.HashMap.

In any event, if T is a type parameter of your interface -- which it probably should be -- then you shouldn't be including the <String> in the subclasses at all. It should just be

public interface Interface<T> {
  public Result query(T query);
}

public class Subclass implements Interface<String> {
  ...
  public Result query(String queryStr) { 
    ...
  }
}