posted 14 years ago
An interface does not provide any implementation and is, therefore, abstract by definition. This means that it cannot be instantiated, but
classes can implement it by providing implementations for its method prototypes. Declaring an interface abstract is superfluous and
seldom done.
Interfaces with empty bodies are often used as markers to tag classes as having a certain property or behavior.
Example : java.lang.Cloneable, java.io.Serializable,
java.util.EventListener.