java state machine car

Table of Contents ⇒ Java Algorithm Library-Artery-Sample

Q08_01.java

package jp.avaj.lib.algo;

import jp.avaj.lib.test.ArTest;

/**
ArStateMechine-State machine-Automobile

Take a car as a very simple sample of a state machine
・ It's too easy compared to an actual car, but it does the following:
・ Step on the accelerator ⇒ Engine rotates ⇒ Wheels rotate
・ Release the accelerator ⇒ The engine stops ⇒ The wheels stop

-In this sample, ArStateMachineDefault is used as an implementation of ArStateMachine.
-ArStateMachineDefault can raise more events when the state machine changes
・ Accelerator ⇒ engine ⇒ wheel event transmission uses this function.

 */
public class Q08_01 {

  public static void main(String[] args) {
    //Wheel condition machine
    ArStateMachineDefault wheel = new ArStateMachineDefault();
    {
      //State transition matrix
      ArStateTransition[] matrix = new ArStateTransition[] {
        //Stop event during rotation ⇒ Stop
        new ArStateTransition(WheelState.ROTATE,WheelEvent.OFF,WheelState.STOP,null),
        //Operation event while stopped ⇒ Rotate
        new ArStateTransition(WheelState.STOP,WheelEvent.ON,WheelState.ROTATE,null),
      };
      //Initial setting,Initially stopped
      wheel.init(WheelState.STOP, matrix);
    }
    //Engine state machine
    ArStateMachineDefault engine = new ArStateMachineDefault();
    {
      //State transition matrix
      ArStateTransition[] matrix = new ArStateTransition[] {
        //Stop event during rotation ⇒ Stop, WheelEvent.Turn off
        new ArStateTransition(EngineState.ROTATE,EngineEvent.OFF,EngineState.STOP,WheelEvent.OFF),
        //Start event while stopped ⇒ Rotate, WheelEvent.Turn off
        new ArStateTransition(EngineState.STOP,EngineEvent.ON,EngineState.ROTATE,WheelEvent.ON)
      };
      //Initial setting, initially stopped
      engine.init(EngineState.STOP,matrix);
      //Connect with wheels(true connects,false disconnects)⇒ Event is sent
      engine.connect(wheel,true);
    }
    //Accelerator state machine
    ArStateMachineDefault accel = new ArStateMachineDefault();
    {
      //State transition matrix
      ArStateTransition[] matrix = new ArStateTransition[] {
        //Event to release while stepping on ⇒ OFF,EngineEvent.Turn off
        new ArStateTransition(AccelState.ON,AccelEvent.OFF,AccelState.OFF,EngineEvent.OFF),
        //Event to step on while separated ⇒ Turn on,EngineEvent.Turn on
        new ArStateTransition(AccelState.OFF,AccelEvent.ON,AccelState.ON,EngineEvent.ON)
      };
      //Initial setting, initially separated
      accel.init(AccelState.OFF,matrix);
      //Connect with the engine(true connects,false disconnects)⇒ Event is sent
      accel.connect(engine,true);
    }

    //Start a test case
    ArTest.startTestCase("Q08_01");

    //Step on the accelerator
    accel.sendEvent(AccelEvent.ON);
    //Make sure the engine is running
    ArTest.equals("accel:on","expected",EngineState.ROTATE,"engine",engine.getState());
    //Make sure the wheels are spinning
    ArTest.equals("accel:on","expecteed",WheelState.ROTATE,"wheel",wheel.getState());

    //Release the accelerator
    accel.sendEvent(AccelEvent.OFF);
    //Make sure the engine is stopped
    ArTest.equals("accel:off","expected",EngineState.STOP,"engine",engine.getState());
    //Make sure the wheels are stopped
    ArTest.equals("accel:off","expecteed",WheelState.STOP,"wheel",wheel.getState());

    //End the test case
    ArTest.endTestCase();
  }
  /**Accelerator status. */
  static enum AccelState { ON,OFF; }
  /**Event to accelerator. */
  static enum AccelEvent { ON,OFF; }

  /**Engine condition. */
  static enum EngineState { ROTATE,STOP; }
  /**Event to engine. */
  static enum EngineEvent { ON,OFF; }

  /**Wheel condition. */
  static enum WheelState { ROTATE,STOP; }
  /**Event to the wheel. */
  static enum WheelEvent { ON,OFF; }
}

The result is as follows.

result.txt

**** Q08_01 start ****
OK accel:on:expected=ROTATE:engine=ROTATE
OK accel:on:expecteed=ROTATE:wheel=ROTATE
OK accel:off:expected=STOP:engine=STOP
OK accel:off:expecteed=STOP:wheel=STOP
**** Q08_01 summary ****
test count = 4
success    = 4