// streams/Signal.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.*;
import java.util.stream.*;
import java.util.function.*;

public class Signal {
 private final String msg;
 public Signal(String msg) { this.msg = msg; }
 public String getMsg() { return msg; }
 @Override
 public String toString() {
 return "Signal(" + msg + ")";
 }
 static Random rand = new Random(47);
 public static Signal morse() {
 switch(rand.nextInt(4)) {
 case 1: return new Signal("dot");
 case 2: return new Signal("dash");
 default: return null;
 }
 }
 public static Stream<Optional<Signal>> stream() {
 return Stream.generate(Signal::morse)
 .map(signal -> Optional.ofNullable(signal));
 }
}