What is the primary benefit of Encapsulation?

In Java, an interface is a blueprint of a class that contains only abstract methods (methods without a body) and constant fields. An interface is used to define a common behavior for multiple classes, allowing them to work together. Interfaces provide a way to achieve abstraction in Java and are used to define a contract that must be implemented by concrete classes. By implementing an interface, a class agrees to perform the behavior specified in the interface. Interfaces can also be extended by other interfaces, making it possible to define a hierarchy of behaviors.

In Java, some of the features of an interface include:

1. Abstract methods: Interfaces can only contain abstract method declarations, and they cannot contain method implementations.

2. No Constructors: Interfaces cannot contain constructor methods.

3. 100% abstraction: Interfaces are 100% abstract, which means that they only contain abstract methods and constants.

4. Multiple inheritance: Interfaces allow multiple inheritance, which means that a class can implement more than one interface.

5. Strong typing: Interfaces enforce strong typing, which means that variables declared as an interface type must only be assigned reference values that implement that interface.

6. Accessibility: Interface methods are public by default and cannot be declared as private or protected.

7. Constants: Interfaces can contain constant declarations, which are public, static, and final by default.

8. Marker interfaces: An interface that does not contain any methods or constants is known as a marker interface, such as Serializable, Cloneable, and Remote.