// functional/ProduceFunction.java // (c)2017 MindView LLC: see Copyright.txt // We make no guarantees that this code is fit for any purpose. // Visit http://OnJava8.com for more book information. import java.util.function.*; interface FuncSS extends Function {} // [1] public class ProduceFunction { static FuncSS produce() { return s -> s.toLowerCase(); // [2] } public static void main(String[] args) { FuncSS f = produce(); System.out.println(f.apply("YELLING")); } } /* Output: yelling */