<< Chapter < Page Chapter >> Page >

Simple event handlers

In this demo program, the event handlers simply display messages on the screen, and in the case of the close button, terminatethe program. In a real world program, the behavior of the event handlers would likely be much more substantive, but the overall skeleton of the program neednot be any different from that illustrated here.

Run the program

I encourage you to copy the code from Listing 10 . Compile the code and execute it. Experiment with the code,making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.


In addition to a number of other items, a class definition can contain:

  • Member classes
  • Local classes
  • Anonymous classes
  • Nested top-level classes and interfaces

Member classes and local classes were explained in previous modules. This module explains anonymous classes.

Although there are some differences, an anonymous class is very similar to a local class without a name. Instead ofdefining a local class and then instantiating it, you can often use an anonymous class to combine these two steps.

An anonymous class is defined by a Java expression, not a statement. Therefore, an anonymous class definition canbe included within a larger overall Java expression.

Anonymous class definitions are often included as arguments to method calls, or as the right operand ofassignment operators.

An object of an anonymous class must be internally linked to an object of the enclosing class.

There is no such thing as an anonymous interface, a local interface, or a member interface.

An anonymous class can often be defined very close to its point of use. Once you become accustomed tothe somewhat cryptic syntax used with anonymous classes, this can lead to improved code readability.

Probably the most important benefit of anonymous classes has to do with accessing the members of enclosing classes. As withmember classes and local classes, methods of an anonymous class have direct access to all the members of the enclosing classes, including private members.Thus the use of anonymous classes can sometimes eliminate the requirement to connect objects together via constructor parameters. In addition, objects ofanonymous classes have access to final local variables that are declared within the scope of the anonymous class.

An anonymous class can be particularly useful in those cases where

  • There is no reason for an object of the anonymous class to exist in the absence of an object of the enclosing class.
  • There is no reason for an object of the anonymous class to exist outside a method of the enclosing class.
  • Methods of the object of the anonymous class need access to members of the object of the enclosing class.
  • Methods of the object of the anonymous class need access to final local variables and method parameters belonging to the method in which the anonymous class is defined.
  • Only one instance of the anonymous class is needed.
  • There is no need for the class to have a name that is accessible elsewhere in the program.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Object-oriented programming (oop) with java' conversation and receive update notifications?