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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

Discuss the differences between taste and flavor, including how other sensory inputs contribute to our  perception of flavor.
John Reply
taste refers to your understanding of the flavor . while flavor one The other hand is refers to sort of just a blend things.
Faith
While taste primarily relies on our taste buds, flavor involves a complex interplay between taste and aroma
Kamara
which drugs can we use for ulcers
Ummi Reply
omeprazole
Kamara
what
Renee
what is this
Renee
is a drug
Kamara
of anti-ulcer
Kamara
Omeprazole Cimetidine / Tagament For the complicated once ulcer - kit
Patrick
what is the function of lymphatic system
Nency Reply
Not really sure
Eli
to drain extracellular fluid all over the body.
asegid
The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include: 1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
asegid
to transport fluids fats proteins and lymphocytes to the blood stream as lymph
Adama
what is anatomy
Oyindarmola Reply
Anatomy is the identification and description of the structures of living things
Kamara
what's the difference between anatomy and physiology
Oyerinde Reply
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
AI-Robot
what is enzymes all about?
Mohammed Reply
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
yes
Prince
how does the stomach protect itself from the damaging effects of HCl
Wulku Reply
little girl okay how does the stomach protect itself from the damaging effect of HCL
Wulku
it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
Kamara
function of digestive system
Ali Reply
function of digestive
Ali
the diagram of the lungs
Adaeze Reply
what is the normal body temperature
Diya Reply
37 degrees selcius
Xolo
37°c
Stephanie
please why 37 degree selcius normal temperature
Mark
36.5
Simon
37°c
Iyogho
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
Stephanie
37A c
Wulku
what is anaemia
Diya Reply
anaemia is the decrease in RBC count hemoglobin count and PVC count
Eniola
what is the pH of the vagina
Diya Reply
how does Lysin attack pathogens
Diya
acid
Mary
I information on anatomy position and digestive system and there enzyme
Elisha Reply
anatomy of the female external genitalia
Muhammad Reply
Organ Systems Of The Human Body (Continued) Organ Systems Of The Human Body (Continued)
Theophilus Reply
what's lochia albra
Kizito
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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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