83 lines
1.6 KiB
Java
83 lines
1.6 KiB
Java
//: patterns/state/StateMachineDemo.java
|
|
// ©2015 MindView LLC: see Copyright.txt
|
|
// Demonstrates StateMachine pattern
|
|
// and Template method.
|
|
package patterns.state;
|
|
|
|
interface State {
|
|
void run();
|
|
}
|
|
|
|
abstract class StateMachine {
|
|
protected State currentState;
|
|
abstract protected 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");
|
|
try {
|
|
Thread.sleep(500);
|
|
} catch(InterruptedException e) {}
|
|
}
|
|
}
|
|
|
|
class Spin implements State {
|
|
@Override
|
|
public void run() {
|
|
System.out.println("Spinning");
|
|
try {
|
|
Thread.sleep(500);
|
|
} catch(InterruptedException e) {}
|
|
}
|
|
}
|
|
|
|
class Rinse implements State {
|
|
@Override
|
|
public void run() {
|
|
System.out.println("Rinsing");
|
|
try {
|
|
Thread.sleep(500);
|
|
} catch(InterruptedException e) {}
|
|
}
|
|
}
|
|
|
|
class Washer extends StateMachine {
|
|
private int i = 0;
|
|
// The state table:
|
|
private State states[] = {
|
|
new Wash(), new Spin(),
|
|
new Rinse(), new Spin(),
|
|
};
|
|
public 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
|
|
*///:~
|