gistfile1.java

List<Kiwi> listOfKiwis = new ArrayList<Kiwi>();
list.add(new Kiwi());
List<Fruit> listofFruits = listOfKiwis; // This line would actually fail to compile.
listOfFruits.add(new Apple());

for (Kiwi kiwi : listOfKiwis) {
    // ... this will blow up, there's an apple in my kiwis.
}