So how could I export my project into a Java application?
Your project is already a Java application.
I think you're mixing up the idea of creating an application and actually distributing it. Whenever you start a new project with a main method, you are creating a new application.
If you want to export your application so other people can use it, check out the replies you've already gotten. They pretty much answers your question, and if you search the internet you'll find a lot of tutorials.