Compiling with wildcard generics

Question

I'm working on the Java OCP exam, and I came across this question

Given the following code:

Transaction t1 = new Transaction<>(1, 2); //1
Transaction t2 = new Transaction<>(1, "2"); //2

It is required that //1 must compile and //2 must NOT compile. Which of the following declarations of class Transaction will satisfy the request?

The answer is this one:

public class Transaction<T, S extends T> {
   public Transaction(T t, S s) {

   }
}

Which I understand. But when I put this code into an Eclipse project, it works! Here is my code:

class TransactionD<T, S extends T> {
    public TransactionD(T t, S s){
        System.out.println("D: t: " + t.getClass() + " s: " + s.getClass());
    }
}
public class Test1
{
    public static void main(String[] args) {

        TransactionD d1 = new TransactionD<>(1, 2);    //1
        TransactionD d2 = new TransactionD<>(1, "2"); //2
    }

}

My output is this:

D: t: class java.lang.Integer s: class java.lang.Integer

D: t: class java.lang.Integer s: class java.lang.String

My question is this: what am I missing?

Answer 1

Since you are using raw types in your declaration, you are actually using TransactionD<Object, Object>, and this makes the call valid, as according to java generics, Object extends Object, and both Integer and String also extend Object.