Interface – Interface is the blueprint of class, specifying what a class should do. The interface in Java refers to an abstract “class” that is used to group related methods with “empty ...

Create packages, import packaged classes and interfaces into your programs, move packages, and encapsulate them in jar files.

In this Java 101 tutorial, I’ve explained how interfaces differ from classes, and showed you how to declare, implement, and extend interfaces in your Java programs.

The interfaces java.util.List and java.util.Set extend Collection, representing more specialized data structures and adding more operations and/or constraints.