// functional/MethodReferences.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.*;

interface Callable { // [1]
 void call(String s);
}

class Describe {
 void show(String msg) { // [2]
 System.out.println(msg);
 }
}

public class MethodReferences {
 static void hello(String name) { // [3]
 System.out.println("Hello, " + name);
 }
 static class Description {
 String about;
 Description(String desc) { about = desc; }
 void help(String msg) { // [4]
 System.out.println(about + " " + msg);
 }
 }
 static class Helper {
 static void assist(String msg) { // [5]
 System.out.println(msg);
 }
 }
 public static void main(String[] args) {
 Describe d = new Describe();
 Callable c = d::show; // [6]
 c.call("call()"); // [7]

 c = MethodReferences::hello; // [8]
 c.call("Bob");

 c = new Description("valuable")::help; // [9]
 c.call("information");

 c = Helper::assist; // [10]
 c.call("Help!");
 }
}
/* Output:
call()
Hello, Bob
valuable information
Help!
*/