This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Because neither the compiler nor the JVM can guarantee that the object is an ArrayList<HttpSession>, only that it's an ArrayList, you will never get this to work without a warning. So in cases like this you have to suck it up and use @SuppressWarnings("unchecked").