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.
You could ofcourse use List<Object> but that would not be really type-safe. If the things you want to store are always triplets of Long, Float and String, then when you use a List<Object> the compiler will not be able to check that for you, and you might inadvertently put an Object into the list that contains something else than a Long, Float and String.