It is subjective to say whether Java GUI is better than Python GUI. both Java and Python have their own strengths and weaknesses when it comes to GUI development, now let’s talk little bit more about this.
Java has different libraries and frameworks for GUI development such as JavaFX and Swing, which are mature and well documented. JavaFX is modern and rich client platform for creating desktop, mobile and web based applications and Swing is lightweight and platform independent GUI library. Java is also supported by many IDEs (Integrated Development Environments) such as Eclipse, IntelliJ IDEA, and NetBeans which provide rich set of tools and features to help developers create GUI based applications quickly.
Python also has different libraries and frameworks for GUI development such as Tkinter, PyQt, wxPython and PySide. Tkinter is the standard GUI library for Python, it is included in the Python standard library, making it easily accessible to developers. PyQt is set of Python bindings for the Qt library, it offers a lot of functionalities, and it can create highly customizable, professional looking apps. wxPython is cross platform GUI toolkit for the Python programming language, it is a wrapper around the wxWidgets C++ library and PySide is a binding of the cross-platform GUI toolkit Qt.