Main.java

// I have:
// Fruit.java: public class Fruit { }
// Apple.java: public class Apple extends Fruit { }

// Main.java:
import java.util.LinkedList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<? extends Fruit> myFruits = new LinkedList<Fruit>();
        List<? extends Fruit> myApples = new LinkedList<Apple>();

        myFruits.add(new Fruit());
        myApples.add(new Fruit());
        myFruits.add(new Apple());
        myApples.add(new Apple());
    /* All four give:
    The method add(capture#1-of ? extends Fruit) in the type
    List<capture#1-of ? extends Fruit>
    is not applicable for the arguments (Fruit)
    */
    }
}