Interviewer And Interviewee Guide

Professional Java Swing Programming Interview Questions & Answers:

1. What are the advantages of the event-delegation model over the event-inheritance model?

Event-delegation model has two advantages over event-inheritance model. a)Event delegation model enables event handling by objects other than the ones that generate the events. This allows a clean separation between a component's design and its use. b)It performs much better in applications where many events are generated. This performance improvement is due to event-delegation model does not have to be repeatedly process unhandled events as is the case of the event-inheritance.

2. What is an event and what are the models available for event handling?

Changing the state of an object is called an event. An event is an event object that describes a state of change. In other words, event occurs when an action is generated, like pressing a key on keyboard, clicking mouse, etc. There different types of models for handling events are event-inheritance model and event-delegation model

3. Which method is used for setting security in applets?

setSecurityManager()
Method is used for setting security in applets

4. What is the lifecycle of an applet?

init( ) method - called when an applet is first loaded start( ) method - called each time an applet is started paint( ) method - called when the applet is minimized or maximized stop( ) method - called when the browser moves off the applet's page destroy( ) method - called when the browser is finished with the applet

5. When we should go for codebase in applet?

If the applet class is not in the same directory, codebase is used.

6. Which method is used by the applet to recognize the height and width?

getParameters()
Method is used by the applet to recognize the height and width.

7. What is the difference between applications and applets?

Application must be run explicitly within Java Virtual Machine whereas applet loads and runs itself automatically in a java-enabled browser. Application starts execution with its main method whereas applet starts execution with its init method. Application can run with or without graphical user interface whereas applet must run within a graphical user interface. In order to run an applet we need a java enabled web browser or an appletviewer.

8. What is an applet?

Applet is a java program that runs inside a web browser.

9. Why should any swing call back implementation execute quickly?

Callbacks are invoked by the event dispatch thread. Event dispatch thread blocks processing of other events as long as call back method executes.

10. What is the What is the difference between invokeAndWait() and invokeLater()? ?

invokeAndWait() method in swing is synchronous. It blocks until Runnable task is complete. InvokeLater() method in swing is asynchronous. It posts an action event to the event queue and returns immediately. It will not wait for the task to complete

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