Can interface contain class in C#?
C# does not allow classes in interfaces.
Can I have a class inside an interface?
Yes, you can define a class inside an interface. In general, if the methods of the interface use this class and if we are not using it anywhere else we will declare a class within an interface.
CAN interfaces have nested classes?
Nesting classes in interfaces. Despite its strangeness, being able to nest a class inside an interface can be useful, especially when there is a tight relationship between the enclosing interface and the enclosed class. Capturing this relationship improves the source code’s readability.
Can we create object inside interface?
No, you cannot instantiate an interface. Generally, it contains abstract methods (except default and static methods introduced in Java8), which are incomplete.
CAN interface have private methods in C#?
Interface cannot include private, protected, or internal members. All the members are public by default. Interface cannot contain fields, and auto-implemented properties. A class or a struct can implement one or more interfaces implicitly or explicitly.
Can an interface have a constructor in C#?
An interface does not have a constructor so one can only create an object of an interface as a subtype. Use of interfaces as instance variables have to be as a subtype of the classes implementing the interface.
How do you define a class in an interface?
To declare a class that implements an interface, you include an implements clause in the class declaration. Your class can implement more than one interface, so the implements keyword is followed by a comma-separated list of the interfaces implemented by the class.
What is inner class interface?
An interface which is declared inside another interface or class is called nested interface. They are also known as inner interface. Since nested interface cannot be accessed directly, the main purpose of using them is to resolve the namespace by grouping related interfaces (or related interface and class) together.
Can an interface have a concrete class?
Concrete methods in an interface All the methods in an interface must be abstract, you cannot have a concrete method (the one which has body) if you try to do so, it gives you a compile time error saying “interface abstract methods cannot have body”.
Can we create constructor in interface?
No, you cannot have a constructor within an interface in Java. You can have only public, static, final variables and, public, abstract, methods as of Java7. From Java8 onwards interfaces allow default methods and static methods.
Why abstract class has no object creation?
Because it’s abstract and an object is concrete. An abstract class is sort of like a template, or an empty/partially empty structure, you have to extend it and build on it before you can use it.
Can we have constructor in interface?
No, you cannot have a constructor within an interface in Java. You can have only public, static, final variables and, public, abstract, methods as of Java7. From Java8 onwards interfaces allow default methods and static methods. From Java9 onwards interfaces allow private and private static methods.