Generic collection & wildcard in java

Question

I am having problems getting my head around generics in the following situation, see inline comments below for my questions:

public void exampleMethod() {
    //         


        

Answer 1

You don't need wildcards here In your case it would suffice to say

Set test;

And you can then put any subclass of AbstractGroup into the set.

Also, it doesn't look like you're initializing test in your code above.