Can i use wildCard in Type parameter reference?

Question

Example:
class A<T>{
void show(T<? >) {}
}

Is it valid or invalid

Answer 1

// yes

class A<T> {
T store;
void show(A<?> a) {
System.out.println( a.store);
}
}

public class Program {
public static void main(String[] args) {
A<String> aStr = new A<>();
A<Integer> aInt = new A<>();
aInt.store = 110;
aStr.show( aInt );
}
}