// functional/MethodReferences.java

// (c)2016 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ 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;

public 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!

*/