I haven’t tested this with other Java components, but if you want/need to get the “system font”, this code gets the default system font from a JEditorPane component:
val outputArea = new JEditorPane val fontFamily = outputArea.getFont.getFamily
That code is written in Scala, but as you can see, it converts easily to Java. On Mac OS X 10.10, fontFamily ends up being “Lucida Grande”.