Can an inner class implement an interface?

Can an inner class implement an interface?

A normal class can implement any number of interfaces but anonymous inner class can implement only one interface at a time. A regular class can extend a class and implement any number of interface simultaneously.

Can you have an inner class inside a method and what variables can you access?

There are basically four types of inner classes in java. Nested Inner class can access any private instance variable of outer class. Like any other instance variable, we can have access modifier private, protected, public and default modifier. Like class, interface can also be nested and can have access specifiers.

How do you implement an inner interface?

Example of nested interface which is declared within the class

1. class A{
2. interface Message{
3. void msg();
4. }
5. }
6. class TestNestedInterface2 implements A.Message{
7. public void msg(){System.out.println("Hello nested interface");}
8. public static void main(String args[]){

Can we create object for inner class?

In the case of normal or regular inner classes, without an outer class object existing, there cannot be an inner class object.

Can an interface contain constants?

It's possible to place widely used constants in an interface. If a class implements such an interface, then the class can refer to those constants without a qualifying class name. This is only a minor advantage.

Can interface contain static methods?

Static methods in an interface since java8 Since Java8 you can have static methods in an interface (with body). You need to call them using the name of the interface, just like static methods of a class.

Which option is correct about the inner class?

Option B is correct because a method-local inner class can be abstract, although it means a subclass of the inner class must be created if the abstract class is to be used (so an abstract method-local inner class is probably not useful).

Can abstract class have inner class?

It does not matter whether your class is abstract or concrete, as long as the nested class is either public , protected or the subclass is in the same package and the inner class is package private (default access modifier), the subclass will have access to it.

Can we have interface inside interface?

An interface can be declared inside another interface also. We mention the interface as i_name1. i_name2 where i_name1 is the name of the interface in which it is nested and i_name2 is the name of the interface to be implemented. // interface inside another interface.

What does an interface contain?

Interfaces can contain instance methods, properties, events, indexers, or any combination of those four member types. Interfaces may contain static constructors, fields, constants, or operators. An interface can't contain instance fields, instance constructors, or finalizers.

Can a Java interface have an inner class?

If you say that “there's no such thing as an "static inner class"” your answer that “you can create both a nested class or an inner class inside a Java interface” is fundamentally wrong. Using your narrowed definition, interfaces can not have inner classes.

Can a class be defined 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. Example.

Which is an example of an inner class?

Since classes may be defined as inner classes to interfaces, we can use inner classes to provide default or alternate implementations for interfaces. An Example In the following example we see the definition of a Stack interface with the usual push and pop operations.

Can a nested class have an inner class?

Using your narrowed definition, interface s can not have inner classes. You can omit the static modifier of an interface ’s nested class but still, it’s a nested class, not an inner class. – Holger Nov 14 '14 at 12:04 This answer is wrong. Interfaces can have static nested classes but not inner classes. – Paul Boddington Mar 29 '15 at 18:20