Can interface variables be protected?

Therefore, the members of an interface cannot be protected.

Can we use private or protected member variables in an interface?

No, it is not possible to define private and protected modifiers for the members in interfaces in Java. As we know that, the members defined in interfaces are implicitly public or in other words, we can say the member defined in an interface is by default public.

Are variables in interface public?

All variables declared inside interface are implicitly public, static and final. All methods declared inside interfaces are implicitly public and abstract, even if you don’t use public or abstract keyword.

Why are interface variables public?

Since instance variables represents the state of an object, interfaces do not have instance variables (being them private or public). And since private static variables represent the state of a class, they don’t have private static variables either.

Can Java interface have protected?

Protecting a constructor prevents the users from creating the instance of the class, outside the package. During overriding, when a variable or method is protected, it can be overridden to other subclass using either a public or protected modifier only. Outer class and interface cannot be protected.

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Why protected is not allowed in interface?

2 Answers. Protected methods are intended for sharing implementation with subclasses. Interfaces have nothing to offer as far as implementation sharing goes, because they have no implementation at all. Therefore all methods on interfaces must be public.

Which member is not allowed in interface?

Private members don’t make sense in interface. Interface is a way to access a class with defined methods where you don’t need to see the inners of that class. Private members disagree to that. Members of a class that are declared private are not inherited by subclasses of that class.

Can interface contain variables?

Like a class, an interface can have methods and variables, but the methods declared in an interface are by default abstract (only method signature, no body). Interfaces specify what a class must do and not how.

CAN interface have final variable?

An interface is a container of abstract methods and static final variables. The interface contains the static final variables.

CAN interface have non final variables?

No you cannot have non-static variables in an interface. By default, All the members (methods and fields) of an interface are public.

Can an interface have an inner class?

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 interface have final methods?

14 Answers. A final method can’t be overridden. … All methods are instance methods. Since the only goal of an interface is to have classes implementing them, and since methods in interfaces can’t have any implementation, making them final would make no sense: they would have no implementation, and could not be overridden …

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Can an interface extend another interface?

An interface can extend other interfaces, just as a class subclass or extend another class. However, whereas a class can extend only one other class, an interface can extend any number of interfaces. The interface declaration includes a comma-separated list of all the interfaces that it extends.

Can a interface be private?

An interface only can be private if it is a nested interface. A toplevel class or interface either can be public or package-private.

Can interface methods be private?

2. Defining Private Methods in Interfaces. Private methods can be implemented static or non-static. This means that in an interface we are able to create private methods to encapsulate code from both default and static public method signatures.

Can abstract class have private variables?

Abstract classes can have private methods. Interfaces can’t. Abstract classes can have instance variables (these are inherited by child classes). … Finally, a concrete class can only extend one class (abstract or otherwise).