77 lines
1.5 KiB
Java
77 lines
1.5 KiB
Java
// patterns/state/StateMachineDemo.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// The State Machine pattern.
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// {java patterns.state.StateMachineDemo}
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package patterns.state;
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import java.util.*;
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import onjava.Nap;
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interface State {
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void run();
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}
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abstract class StateMachine {
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protected State currentState;
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protected abstract boolean changeState();
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// Template method:
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protected final void runAll() {
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while(changeState())
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currentState.run();
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}
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}
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// A different subclass for each state:
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class Wash implements State {
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@Override public void run() {
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System.out.println("Washing");
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new Nap(0.5);
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}
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}
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class Spin implements State {
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@Override public void run() {
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System.out.println("Spinning");
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new Nap(0.5);
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}
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}
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class Rinse implements State {
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@Override public void run() {
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System.out.println("Rinsing");
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new Nap(0.5);
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}
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}
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class Washer extends StateMachine {
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private int i = 0;
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private Iterator<State> states =
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Arrays.asList(
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new Wash(), new Spin(),
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new Rinse(), new Spin()
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).iterator();
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Washer() { runAll(); }
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@Override public boolean changeState() {
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if(!states.hasNext())
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return false;
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// Set the surrogate reference
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// to a new State object:
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currentState = states.next();
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return true;
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}
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}
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public class StateMachineDemo {
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public static void main(String[] args) {
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new Washer();
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}
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}
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/* Output:
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Washing
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Spinning
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Rinsing
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Spinning
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*/
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