You may recall that, when using collections of objects, casts are often required to specify the type being used. By specifying a generic, the correct type is returned, thus eliminating the need for certain casts. You will cover generics in much more detail in the near future.

However, the reason that generics come up at this point is because they are at the heart of the warning message you received in the previous compile. The error message indicates that the add() method performs an unchecked operation. myList.add("One");

You are, in fact, adding a String to this ArrayList; however, you have not specified the type of the parameter in the definition of the ArrayList. ArrayList myList = new ArrayList();

Note that, in the previous line of code, you have used original syntax (pre Java SE 1.5) when declaring the myList. Thus, any legacy code written prior to Java SE 1.5 will result in the warnings.