What options are for a GUI for a Java application?

This might be a bit of a wide question. I have a couple of classes in Java that take input a String which is a mathematical expression and evaluates it.

I want to implement a desktop GUI for this. The user inputs the equation in a textfield and a couple of rectangles should be displayed under the textfield if the equation is not written correctly pointing at the syntax errors?

This is the closest thing I’ve come to what I want and it’s not related to a GUI in Java http://web.cortland.edu/flteach/mm-course/glossPopupDiv.html

I use NetBeans. What can I use/How can I create a GUI for the application other than JFrame? Is there any way I could create the GUI in Javascript? Anything that can point me someplace is appreciated.