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The public access modifier

A public instance variable can be accessed by any code in any method in any object that can obtain a reference to the object to which thevariable belongs. However, you must first gain access to the object in order to gain access to the variable. Normally you gain access to the object using areference to the object and then gain access to a member of the object such as a variable or method. This is indirection .

The private access modifier

A private instance variable can be accessed by any code in any method that is defined in the class of the object to which the variablebelongs.

The protected access modifier

A protected instance variable can be accessed by the same methods that can access a private instance variable plus methods in subclasses of the class of the object to which the instance variablebelongs.

I'm not going to try to explain the scope of internal and protected internal instance variables for the reasons that I discussed earlier.

Local variables

A local variable is declared inside a method or constructor. The lifetime of a local variable is limited to the time that control remains within the block ofcode in which the variable is declared. The scope of the variable is limited to the code block in which it is declared and then only to the statements followingthe declaration statement.

Class variables

A class variable belongs to a static class. I believe that the lifetime of a class variable is the same as the lifetime of the program in which the class isloaded.

It is not necessary to instantiate an object of the static class in order to access the variable. Assuming that you have access rights to the variable, youcan access it simply by joining the name of the class to the name of the variable using the dot operator.

More bad programming practice

I personally consider it bad programming practice to use class variables in most cases unless the variables are actually constants. However, there are a fewsituations where you have no choice but to use a non-constant class variable.

Reference variables

A reference variable contains a reference to an object or contains null. You typically use the value stored in a reference variable to locate an object inmemory. Once you locate the object, you typically use the dot operator along with the name of a variable or a method to ask the object to do something. Thisis called indirection .

Primitive variables

Primitive variables contain primitive values. No indirection is required to access the primitive value stored in a primitive variable.

An analogy

An analogy that I often use to explain the difference between a reference variable and a primitive variable goes as follows.

A primitive variable is analogous to your wallet.

If you get robbed and the robber takes your wallet, he has your money because the wallet contains your money just like a primitive variable contains aprimitive value.

A reference variable is analogous to your check book.

If the robber takes your checkbook, he doesn't have your money -- not yet anyway. The checkbook doesn't contain your money. Instead, it contains areference to your bank where your money is stored. A reference variable doesn't contain an object; it contains a reference to an object. Furthermore, two ormore reference variables can contain references to the same object but this is usually not a good idea.

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
how do they get the third part x = (32)5/4
kinnecy Reply
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?
is it a question of log
I rally confuse this number And equations too I need exactly help
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
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
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?
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
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, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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