In my current project we have to develop a good looking desktop based application in java.
Currently, we have a very basic desktop application written in swing and team does not have good swing knowledge. Can we create a very good looking UI in swing?
Should we use JavaFX for creating the desktop application?
What are other alternatives to do this?
Swing is very flexible with regards to look-and-feel and you can certainly make very good looking applications with Swing.
I recommend the book Filthy Rich Clients by Chet Haase and Romain Guy if you want to learn how to make nice Swing GUI applications.
Check out http://www.pushing-pixels.org/. Kirill is the author of Substance which provides a ton of new look and feel options for Swing. Here's a blog entry which shows a little bit of what is possible with Swing. There used to be a link to his 2007 presentation at Java One, but unfortunately the link no longer works.