Welcome to JavaRanch
There are two kinds of types in
Java: primitive types and reference types. An interface is a reference type; just like a class. However, the difference is that an interface is an abstract reference type. An abstract reference type is a reference type that is not fully defined; it is just an abstraction. Because it is not fully defined, an abstract reference type cannot be instantiated. It can be fully defined by:
extending it - extend an abstract class and provide concrete implementations for all of its abstract methodsimplementing it - implement an interface and provide concrete implementations for all of its abstract methods