What is non nested class in Java?
A non-static nested class is a class within another class. It has access to members of the enclosing class (outer class). It is commonly known as inner class . Since the inner class exists within the outer class, you must instantiate the outer class first, in order to instantiate the inner class.
What is nested interface?
An interface, i.e., declared within another interface or class, is known as a nested interface. The nested interfaces are used to group related interfaces so that they can be easy to maintain. The nested interface must be referred to by the outer interface or class. It can’t be accessed directly.
What are classes and interfaces?
Differences between a Class and an Interface:
| Class | Interface |
|---|---|
| A class can be instantiated i.e, objects of a class can be created. | An Interface cannot be instantiated i.e, objects cannot be created. |
| Classes does not support multiple inheritance. | Interface supports multiple inheritance. |
What are nested classes in Java?
A nested class is a member of its enclosing class. Non-static nested classes (inner classes) have access to other members of the enclosing class, even if they are declared private. Static nested classes do not have access to other members of the enclosing class.
Can we define an interface within the class?
Yes, you can define an interface inside a class and it is known as a nested interface. You can’t access a nested interface directly; you need to access (implement) the nested interface using the inner class or by using the name of the class holding this nested interface.
Can interfaces be nested?
We can declare interfaces as member of a class or another interface. Such an interface is called as member interface or nested interface.
What are interfaces for in Java?
In Java, an interface is an abstract type that contains a collection of methods and constant variables. It is one of the core concepts in Java and is used to achieve abstraction, polymorphism and multiple inheritances. We can implement an interface in a Java class by using the implements keyword.
Can we interface inside class?