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Can Java interface be 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.
Can we make interface as protected?
In general, the protected members can be accessed in the same class or, the class inheriting it. But, we do not inherit an interface we will implement it. Therefore, the members of an interface cannot be protected.
What types of methods can an interface have?
The interface body can contain abstract methods, default methods, and static methods. An abstract method within an interface is followed by a semicolon, but no braces (an abstract method does not contain an implementation).
Can we create variable in interface?
You shouldn’t put any variables inside Interfaces. Because interfaces define contracts which can be implemented in various ways. The value of a variable is implementation. We certainly can when we know all the classes implementing the interface have some constant variables(Field names for instance).
Can we define protected members in interface?
Interfaces can also have protected members. They are not accessible by the derived class, but via the derived interface. If the class wants to implement the protected member, it has to be done via implementing interface explicitly. Interfaces can also have virtual members, but the class can’t override the method.
Can we write method body in interface?
Interfaces are declared using the interface keyword, and may only contain method signature and constant declarations (variable declarations that are declared to be both static and final ). All methods of an Interface do not contain implementation (method bodies) as of all versions below Java 8.
CAN interface have final variable?
an interface can be empty, with no methods or variables in it. we can’t use the final word in the interface definition, as it will result in a compiler error. all interface declarations should have the public or default access modifier; the abstract modifier will be added automatically by the compiler.
Are there private methods in interfaces in Java 9?
Java 9 onwards, you can include private methods in interfaces. Before Java 9 it was not possible. In Java SE 7 or earlier versions, an interface can have only two things i.e. Constant variables and Abstract methods. These interface methods MUST be implemented by classes which choose to implement the interface.
Can We declare interface members as private or protected in Java8?
Can we declare interface members as private or protected in java8? Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static. Since all the methods are abstract you cannot instantiate it.
Can a private method be protected in Java?
However, this is a non-issue: unless someone is trying to crack your code, they’re not going to invoke random methods. Instead, think of private / protected methods as defining a contract for subclasses, and use interfaces to define the contract with the outside world.
Why are protected methods not allowed in interfaces?
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.