Generics make your code more flexible and easier to read, and they help you avoid ClassCastExceptions at runtime. Get started with this introduction to using generics with the Java Collections ...

Today both Vector and Hashtable are generic classes, but back then generics were not part of the Java language.

Generics can solve many more problems than collections. Use generics to write code once and reuse it more easily.

The project's goals include a major overhaul of Java's generics, a new approach to generic typing, and new support for value types.

Apache Collections supports generics, so that's not a reason to choose one over the other. If the collections you need are available in it, I'd probably lean towards Guava, though.