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.

For 2018, our most popular articles were Java developer tutorials on new APIs, frameworks such as Spring or the tools and techniques server-side developers use to move code into production. Here is ...

The functional Predicate interface gets used extensively by the Java 8 Streams API. Any developer who wants to master functional programming in Java will need to be comfortable with the Predicate ...

For an introduction to Java interfaces, including the difference between classes and interfaces, see my Java 101 tutorial Working with interfaces in Java. Nesting interfaces in classes ...