Java SE (Java Platform, Standard Edition)

I have inherited a codebase for an application written in Java that runs on Windows. It currently has a swing GUI. It is also a multi-threaded application, and we have experienced problems as not all the GUI components were written in a thread-safe way.

We may be given an opportunity to re-architect the application. Certainly a choice would be to keep the Swing front-end, but ensure the business logic is separated from the UI such that the threading doesn't cause problems like it does today.

But I wonder if there are other choices for a UI Framework for a Windows based application. Is Swing my only choice? Or are there other frameworks available for creating UI's in Java?

Thanks,
Beth