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Questions tagged [nested-class]

In Object Oriented programming, a class defined inside another class. Also called "inner class".

In there are times when a class A is used only as a component of another class B and should not be instanced outside B. In those cases proper encapsulation suggest defining that class as a nested or inner class.

Several languages support this feature (C++, Java, .Net languages, D, python, for example) although with minor differences in where nested classes can be defined, how can they be used; and some languages support more than one variety of nested class.

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Why Would I Ever Need to Use C# Nested Classes

I'm trying to understand about nested classes in C#. I understand that a nested class is a class that is defined within another class, what I don't get is why I would ever need to do this.
Dan Norton
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Are inner classes in C++ automatically friends?

If I define an inner class in C++, is it automatically a friend of the class that contains it? For example, is this legal: class Outer { public: class Inner { public: void mutateOuter(Outer& o); }; private: int…
templatetypedef
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How to restrict access to nested class member to enclosing class?

Is it possible to specify that members of a nested class can be accessed by the enclosing class, but not other classes ? Here's an illustration of the problem (of course my actual code is a bit more complex...) : public class Journal { public…
Thomas Levesque
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Eclipse warning about synthetic accessor for private static nested classes in Java?

My coworker suggested making several of the Eclipse code-formatting and warning settings to be more rigorous. The majority of these changes make sense, but I get this one weird warning in Java. Here's some test code to reproduce the…
Jason S
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Nested/Inner class in external file

I have a class MyClass and an inner class MyNestedClass like this: public class MyClass { ... public class MyNestedClass { ... } } Both classes are very long. Because of that i'd like to seperate them in two different files, without…
Alp
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Using nested enum types in Java

I have a data structure in mind that involves nested enums, such that I could do something like the following: Drink.COFFEE.getGroupName(); Drink.COFFEE.COLUMBIAN.getLabel(); And if there were method declarations: someMethod(Drink…
Chris
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Creating an instance of a nested class in XAML

in a XAML file (a WPF UserControl), is there a way to reference an inner class "B" defined in another class "A" ? public class A { public class B { } } Something like : This syntax does not work because "B" is…
Pragmateek
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C++ nested class/forward declaration issue

Is it possible to forward-declare a nested class, then use it as the type for a concrete (not pointer to/reference to) data member of the outer class? I.E. class Outer; class Outer::MaybeThisWay // Error: Outer is undefined { }; class Outer { …
uj2
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Why can't a class extend its own nested class in C#?

For example: public class A : A.B { public class B { } } Which generates this error from the compiler: Circular base class dependency involving 'A' and 'A.B' I always figured a nested class behaved just like a regular class except with…
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Inner class in interface vs in class

What is the difference between these two innerclass declarations? Also comment on advantages/disadvantages? case A: class within a class. public class Levels { static public class Items { public String value; public String path; …
Blessed Geek
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Can a nested C++ class inherit its enclosing class?

I’m trying to do the following: class Animal { class Bear : public Animal { // … }; class Giraffe : public Animal { // … }; }; … but my compiler appears to choke on this. Is this legal C++, and if not, is…
Tony the Pony
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What are reasons why one would want to use nested classes?

In this stackoverflow answer a commenter mentioned that "private nested classes" can be quite useful so I was reading about them in articles such as this one which tend to explain how nested classes function technically, but not why you would use…
Edward Tanguay
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Nested Class member function can't access function of enclosing class. Why?

Please see the example code below: class A { private: class B { public: foobar(); }; public: foo(); bar(); }; Within class A & B implementation: A::foo() { //do something } A::bar() { //some code foo(); …
Rahul
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Can a Static Nested Class be Instantiated Multiple Times?

Given what I know of every other type of static feature of programming––I would think the answer is 'no'. However, seeing statements like OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass(); makes me wonder.
stormin986
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Private nested Java class in UML diagram

I have a question regarding UML. I have a class which simply contains an inner class with the private access modifier - cannot be accessed from anywhere else... Normally in order to present an inner class relation I can use a (+) relation like here…
radekEm
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