Java Event Handling
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Questions and Answers

What is the primary responsibility of the operating system in a graphical user interface?

  • To execute programs in response to user events
  • To generate events based on user input
  • To monitor the environment for events and pass them to running programs (correct)
  • To provide a standard set of event types for programs to use

What is the purpose of an event listener in Java?

  • To register with an event source and receive notifications when events occur (correct)
  • To provide a standard set of event types for programs to use
  • To encapsulate information about an event that has occurred
  • To generate events that an event source can listen for

What type of event is generated when a button is clicked in Java?

  • Mouse event
  • Action event (correct)
  • Key event
  • Window event

What is the role of an event source in Java?

<p>To register event listeners and notify them when events occur (A)</p> Signup and view all the answers

How does a listener object receive information about an event that has occurred?

<p>The event source passes the event object to the listener object (C)</p> Signup and view all the answers

How does a program register a listener object with an event source in Java?

<p>By implementing the listener interface in a class and creating an instance of that class (A)</p> Signup and view all the answers

Which of the following statements is true about the ButtonPanel class?

<p>It extends the <code>JPanel</code> class and implements the <code>ActionListener</code> interface. (C)</p> Signup and view all the answers

What is the purpose of the addActionListener() method call in the ButtonPanel constructor?

<p>To register the <code>ButtonPanel</code> instance as a listener for button events. (C)</p> Signup and view all the answers

In the actionPerformed() method, what does the getSource() method return?

<p>The reference to the <code>JButton</code> object that triggered the event. (C)</p> Signup and view all the answers

What is the purpose of the repaint() method call in the actionPerformed() method?

<p>To redraw the panel with the new background color. (A)</p> Signup and view all the answers

In the eventFrame class, what is the purpose of the add(new ButtonPanel()) statement?

<p>To create a new instance of the <code>ButtonPanel</code> class and add it to the <code>JFrame</code>. (A)</p> Signup and view all the answers

What is the purpose of the setDefaultCloseOperation(EXIT_ON_CLOSE) method call in the main() method?

<p>To exit the program when the <code>JFrame</code> is closed. (D)</p> Signup and view all the answers

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