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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.

Summary

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 can chip be made from sand
Eke Reply
is this allso about nanoscale material
Almas
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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
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