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 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 ...

Here’s an example of how a Function and lambda expression work together: Function<Integer, String> verboseLambda = (Integer x)-> { return Integer. toString (x*x); }; System.

Don't be intimidated by the prospect of doing functional programming in Java. This step-by-step example will help you learn basic Java lambda syntax quickly and effectively.