Problem:
(a) A GUI can contain text-fields, buttons, and other labels. A button usually triggers an event on the GUI. Explain the different processes in registering an event and handling the action performed by the button, illustrating your answer with necessary piece of code.
(b)
Explain the following terms used in object-oriented programming using suitable Java examples of your own:-
(i) polymorphism
(ii) abstract class
(iii) interface.