private

Although, this is a very basic code, it seems there is something fundamentally flawed in Java, or the JVM used by the Eclipse IDE I have used to run the code. The code runs even though it should not (I think)! The code in A.java simply displays "Hello, I am A!" Here it is: import java.lang.*; import java.util.*; class A { private void methodA() {System.out.println("Hello, I am A!");} public static void main(String[] args) { A a = new A(); a.methodA(); } } I do not understand why, after creating an instance of class A, main() succeeds in running a private method of class A on that instance. Yes

I'm declaring a field: private static final String filename = "filename.txt"; First, does the order of private static final matter? If not, is there a standard accepted sequence or convention? Second, the filename in my application is fixed. Is this the best was to store its value? I use Checkstyle with Eclipse, which results in a warning if the declaration is in a different order to the one you've specified, citing the Java Language Specification (JLS). For example, private final static String filename = "filename.txt"; results in 'static' modifier out of order with the JLS suggestions. They

This is a rather basic OO question, but one that's been bugging me for some time. I tend to avoid using the 'private' visibility modifier for my fields and methods in favor of protected . This is because, generally, I don't see any use in hiding the implementation between base class and child class, except when I want to set specific guidelines for the extension of my classes (i.e. in frameworks). For the majority of cases I think trying to limit how my class will be extended either by me or by other users is not beneficial. But, for the majority of people, the private modifier is usually the

I just spotted this in some code: class Foo { [...] private: virtual void Bar() = 0; [...] } Does this have any purpose? (I am trying to port some code from VS to G++, and this caught my attention) See this Herb Sutter article as to why you'd want to do such a thing. This is a pure virtual function that happens to be private. This makes it so that a derived class must implement the method. In this case Bar. I think you may be confused b/c this is done to create "interfaces" in C++ and a lot of times people think of these as public. There are cases where you may want to define an interface that

Is there a way to hide private data members of a C++ class away from its users, in the cpp file? I think of the private members as part of the implementation and it seems a little backwards to declare them in the header file. Kristopher Johnson The "pimpl" idiom is how this is generally handled. See http://www.gotw.ca/gotw/024.htm http://www.gotw.ca/gotw/028.htm http://herbsutter.com/gotw/_100/ (updated for C++11) you want to use something like the PIMPL idiom http://en.wikipedia.org/wiki/Opaque_pointer See Pimpl Idiom The classic way to do this is with a proxy pointer to an internal class

What's the best way to unit test protected and private methods in Ruby, using the standard Ruby Test::Unit framework? I'm sure somebody will pipe up and dogmatically assert that "you should only unit test public methods; if it needs unit testing, it shouldn't be a protected or private method", but I'm not really interested in debating that. I've got several methods that are protected or private for good and valid reasons, these private/protected methods are moderately complex, and the public methods in the class depend upon these protected/private methods functioning correctly, therefore I