// patterns/state/StateMachineDemo.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.
// The StateMachine pattern and Template method
// {java patterns.state.StateMachineDemo}
package patterns.state;
import onjava.Nap;

interface State {
 void run();
}

abstract class StateMachine {
 protected State currentState;
 protected abstract boolean changeState();
 // Template method:
 protected final void runAll() {
 while(changeState()) // Customizable
 currentState.run();
 }
}

// A different subclass for each state:

class Wash implements State {
 @Override
 public void run() {
 System.out.println("Washing");
 new Nap(0.5);
 }
}

class Spin implements State {
 @Override
 public void run() {
 System.out.println("Spinning");
 new Nap(0.5);
 }
}

class Rinse implements State {
 @Override
 public void run() {
 System.out.println("Rinsing");
 new Nap(0.5);
 }
}

class Washer extends StateMachine {
 private int i = 0;
 // The state table:
 private State[] states = {
 new Wash(), new Spin(),
 new Rinse(), new Spin(),
 };
 Washer() { runAll(); }
 @Override
 public boolean changeState() {
 if(i < states.length) {
 // Change the state by setting the
 // surrogate reference to a new object:
 currentState = states[i++];
 return true;
 } else
 return false;
 }
}

public class StateMachineDemo {
 public static void main(String[] args) {
 new Washer();
 }
}
/* Output:
Washing
Spinning
Rinsing
Spinning
*/