Are you Generic?

AreYouGeneric.java

import java.util.ArrayList;
import java.util.List;

/**
 * @author <a href="mailto:khomenko.dp@gmail.com">Oleksandr Khomenko</a>
 * <br>
 */
public class AreYouGeneric {

    public static void main(String[] args) {
        //EXTENDS
        List<? extends String> lol = new ArrayList<>();
        
        //lol.add(new Object()); does not compile
        //lol.add("Lol"); does not compile
        // WTF? We can add only children of String

        for (String l : lol) {
            //but go through strings
        }

        List<? super String> opa = new ArrayList<>();

        //opa.add(new Object()); does not compile
        opa.add("Lol");

//        for (String o : opa) { does not compile
//            
//        }

        for (Object o : opa) {
            // can go only through Object
        }
    }
}