A an interface. Interfaces can specify public methods but can have no implementation of methods. Thus, one can not make an object from an interface. Interfaces can have fields. All fields in an interface are final and static even if they are not explicitly declared as such.
Interfaces have the same access levels as classes, public and package.
A class can implement more that one interface. If a parent class implements an interface, its child classes automatically implement the interface. An interface, like a class, defines a type. Fields, variables, and parameters can be declared to be of a type defined by an interface. This example shows the syntax of declaring an interface and a class implementing the interface.