// 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

*/