In my interface:
public <T> Result query(T query)
In my 1st subclass:
public <HashMap> Result query(HashMap queryMap)
In my 2nd subclass:
public <String> Result query(String queryStr)
1st subclass has no compilation warning at all while 2nd subclass has: The type parameter String is hiding the type String? I understand my parameter is hidden by the generics type. But I want to understand underneath what exactly happened?
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) {
...
}
}
String - or other commonly used Java class names. It will potentially confusing for anyone examining the code later on. If I see String in Java, I assume it's java.lang.String.
