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 example, a Java program obtains file I/O (input/output) services by creating objects from various file-related classes in Java’s class library and calling their methods.

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.

Example UnaryOperator Lambda expression If you implement the UnaryOperator interface with a complete Java class, it will create completely valid code, but it defeats the purpose of working with a ...