JavaOne 2026 Session

Summary

Collections are easy to use in practice. At least, that’s what you'd think after reading most tutorials on the subject. But real life isn’t always so straightforward. You need to apply object design principles intelligently if you want to use collections in a large system without running into trouble.

In this talk, we’ll look at some common system design errors involving collections, and for each one, we’ll figure out a better way. For example, we’ll show how extending the idea of encapsulation to collections leads to thinking about ownership of data and how to safeguard it, allowing you to avoid many problems by using some simple rules. Other topics will include other ways of applying object design principles when a collection doesn’t have exactly the functionality needed.

You’ll leave this presentation with a wider perspective on object-oriented design, and with an understanding of how to detect and eliminate design smells in your system’s use of collections.