SCJP confusing question

Question

Hello guys,
Recently I came across one web-site with mock-up SCJP questions. One of the questions and especially provided answer to it really grabs my attention:
Can one object access a private variable of another object of the same class?
Answer: Yes.
Private means "private to the class", NOT "private to the object". So two objects of the same class could access each other's private data.
If it would be true it violates the encapsulation principle of OO. Can you please explain this question/answer because it is really confusing me.

Answer 1

All kidding aside here - ask yourself: "Why would I want to make anything private in a class?". Then you might answer "Well, for one thing I do not want to be able to de-stabilize the class when I use it for what it is."
An example of such use is any use of the API classes from SUN. No instantiated Object from these has access to the private members, unless though public methods - which control such access.
But you might ask: "And why would I want to take that ability away from the class itself?" Well: "In answer you maight say that you would not want to, and continue by saying that's not what you mean."
Well since one would need to build in that capability - the previous example used an inner class with a change method - this is not the same as allowing outside access. If you tried to do something like from another toplevel public class without any public alteration methods in the member class you couldn't do it - you'd get a "x has private access in y" type message.
~Bill
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