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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.


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

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
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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