In Java\'s graphics, buttons which require a running Java program to perform som

Question

In Java's graphics, buttons which require a running Java program to perform something are associated with a registered controller listener thread button group The difference between an abstract class and an interface is abstract classes can have instance variables abstract classes can have both abstract and concrete methods abstract classes can be used as a base class all of the above When the user clicks on any of the three standard buttons in a JFrame, a ___________ is created Event listener Listener activator window event Action event

Explanation / Answer

19. B. Listener

In java Graphics Clicking a Button while we want it to perform something (or hitting the "Enter" key) fires an ActionEvent to all its ActionEvent listener(s). An ActionEvent listener must implement the ActionListenerinterface, which declares one abstract method.

20. D. all of the above

As Abstract class can have both Abstract and non abstract methods where as interfaces can only have abstract methods.Also absctract class provide the implementation of interface. but vice versa in not true.

21. D.Action Event

explaination is already given in 19. answer.

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