The final keyword has several usages in Java. It corresponds to both the sealed and readonly keywords in C#, depending on the context in which it is used. Classes To prevent subclassing (inheritance from the defined class): Java public final class MyFinalClass {…} C# public sealed class MyFinalClass {…} Methods Prevent overriding of a virtual … Read more
Changing the access modifier of a method in a derived type is pointless that’s why it’s not allowed: Case 1: Override with a more restrictive access This case is obviously not allowed due to the following situation: class Base { public virtual void A() {} } class Derived: Base { protected override void A() } … Read more
From Java documentation If a class has no modifier (the default, also known as package-private), it is visible only within its own package (packages are named groups of related classes — you will learn about them in a later lesson.) At the member level, you can also use the public modifier or no modifier (package-private) … Read more
They are access modifiers and help us implement Encapsulation (or information hiding). They tell the compiler which other classes should have access to the field or method being defined. private – Only the current class will have access to the field or method. protected – Only the current class and subclasses (and sometimes also same-package … Read more
As of Swift 3.0.1, there are 4 levels of access, described below from the highest (least restrictive) to the lowest (most restrictive). 1. open and public Enable an entity to be used outside the defining module (target). You typically use open or public access when specifying the public interface to a framework. However, open access … Read more
Dim and Private work the same, though the common convention is to use Private at the module level, and Dim at the Sub/Function level. Public and Global are nearly identical in their function, however Global can only be used in standard modules, whereas Public can be used in all contexts (modules, classes, controls, forms etc.) … Read more
It’s a fundamental principle in OOP: the child class is a fully-fledged instance of the parent class, and must therefore present at least the same interface as the parent class. Making protected/public things less visible would violate this idea; you could make child classes unusable as instances of the parent class.
The “protected internal” access modifier is a union of both the “protected” and “internal” modifiers. From MSDN, Access Modifiers (C# Programming Guide): protected: The type or member can be accessed only by code in the same class or struct, or in a class that is derived from that class. internal: The type or member can … Read more
What’s going on here? You’ve misunderstood the meaning of protected. You can access the protected members declared in A from within C, but only for instances of C or subclasses of C. See section 6.6.2 of the JLS for details of protected access. In particular: Let C be the class in which a protected member … Read more
The default access for everything in C# is “the most restricted access you could declare for that member”. So for example: namespace MyCompany { class Outer { void Foo() {} class Inner {} } } is equivalent to namespace MyCompany { internal class Outer { private void Foo() {} private class Inner {} } } … Read more