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

The previous two modules explained member classes and local classes. This module will explain anonymous classes.

What is an anonymous class ?

I'm going to begin my discussion with a quotation from one of my favorite authors, David Flanagan, author of Java in a Nutshell .

"An anonymous class is essentially a local class without a name."

If you have read the previous module, you should know quite a lot about local classes at this point in time. Continuing with Flanagan's words,

"Instead of defining a local class and then instantiating it, you can often use an anonymous class to combine these two steps... an anonymousclass is defined by a Java expression , not a Java statement . This means that an anonymous class definition can be included within a larger Java expression..."

As you will see from the sample program in this module, anonymous class definitions are often included as arguments to method calls.

As is the case for an object of a member class or a local class (discussed in previous modules), an object of an anonymous class must be internally linked to an object of the enclosing class.

Thus, an anonymous class is truly an inner class, because an object of the anonymous class cannot exist in the absence of an object of the enclosing class.

What about an anonymous interface ?

Interfaces defined within classes are implicitly static. This means that they are always top-level. There is no such thing as a member interface, a local interface, or an anonymous interface.

Why use anonymous classes ?

As with local classes, objects instantiated from anonymous classes share many of the characteristics of objects instantiated from member classes.However, in some cases, an anonymous class can be defined closer to its point of use than would be possible with a member class or a local class. Once youbecome accustomed to the somewhat cryptic syntax used with anonymous classes, this can often lead to improved code readability.

Probably the most important benefit of anonymous classes has to do with accessing the members of enclosing classes. Just like with member classesand local classes, methods of an anonymous class have direct access to all the members of the enclosing classes, including private members. Thus the useof anonymous classes can often eliminate the requirement to connect objects together via constructor parameters.

In addition, although not demonstrated in this module, as with local classes, objects of anonymous classes have access to final local variables that are declared within the scope of the anonymous class.

Can be particularly useful when ...

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

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris 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?
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
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
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele 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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