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what is the concept of private variable

sudhakar kandasamy

Joined: Dec 09, 2007
Posts: 4
I declare a variable i as derived class cannot access this i value,but if i create a public method getvalue which returns i value,through this method derived class can access this
private variable.Then where is the security for this private variavble.
Frank Carver

Joined: Jan 07, 1999
Posts: 6920
The point of a private variable is that you can only get it by calling a method. This means that the class is free to change the way it stores the information, without hurting other classes. Imagine we have a class:

and another class uses it like:

We now can't change the internal representation of the url. But what if we need to separate it out into the protocol (http) and the address (www,
Imagine we had written it as:

It is now easy to change T1, without needing any changes to the other code:

This approach of "decoupling" the implementation of a class from its use is immensly useful in making code more maintainable. I've written hundreds of thousands of lines of Java, and I rarely use anything other than "private" for data members of classes.

Read about me at ~ Raspberry Alpha Omega ~ Frank's Punchbarrel Blog
yoginee Pathak

Joined: Apr 25, 2001
Posts: 3
hi !
What Frank has said is absolutely right !
In short, private variables are accessible only to the methods in a class.
If you have done some C programming, you know if you declare a variable it is accessible throughout the program.
Read the concept of "encapsulation" carefully and i guess it should solve your problem
I agree. Here's the link:
subject: what is the concept of private variable
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