Basic State Machines

// This example shows a simple state machine
// without any actions or guards
//
// In the following, status is a state machine,
// and acts like an attribute, whose value is set
// by various events.
//
// Open, Closing, Closed, Opening and HalfOpen are
// the possible values, or states, of status.
//
// buttonOrObstacle, reachBottom and reachTop are
// events. These become generated methods that can
// be called to cause a state change.
//
// To make the state diagram appear in
// UmpleOnline, select 'Options' then choose
// 'GraphViz State Diagram'
class GarageDoor
{
   status {
      Open { buttonOrObstacle -> Closing;  }
      Closing {
          buttonOrObstacle -> Opening;
          reachBottom -> Closed;
      }
      Closed { buttonOrObstacle -> Opening; }
      Opening {
          buttonOrObstacle -> HalfOpen;
          reachTop -> Open;
      }
      HalfOpen { buttonOrObstacle -> Opening; }
  }
}
      

// This is a more fully-featured state machine for
// a garage door corresponding to the diagram
// above
class Garage {
  Boolean entranceClear=true;
  GarageDoor { 
    Closed {
      entry/{stopMotor();}  
      entry/{triggerEnergySaveMode();}
      exit/ {triggerNormalEnergyMode();}
      pressButton -> /{turnLightOn();} Opening; 
    }
    Opening {
      entry/{runMotorForward();}
      openingCompleted -> Open;
    }
    Open {
      entry/{stopMotor();}
      // do {wait(60000); turnLightOff();}
      pressButton [getEntranceClear()] -> Closing;
    }
    Closing {
      entry/{runMotorInReverse();}
      closingCompleted -> Closed;
      pressButton -> /{flashLightOn();} Opening; 
    }
  }
  
  boolean runMotorInReverse() Java {
     System.out.println(
       "Running motor in reverse");
    return true;
  }

  boolean runMotorInReverse() Python {
    print("Running motor in reverse")
    return True
  }
  
  boolean flashLightOn() Java {
     System.out.println("Flashing light on");
    return true;
  }

  boolean flashLightOn() Python {
    print("Flashing light on")
    return True;
  }

  boolean turnLightOn() Java {
     System.out.println("Turning light on");
    return true;
  }

  boolean turnLightOn() Python {
    print("Turning light on")
    return True
  }  
  
   boolean turnLightOff() Java {
     System.out.println(
       "Turning light off");
    return true;
  }

   boolean turnLightOff() Python {
    print("Turning light off")
    return True
  }  
  
  boolean runMotorForward() Java {
     System.out.println(
       "Running motor forwards");
    return true;
  }

  boolean runMotorForward() Python {
    print("Running motor forwards")
    return True
  }  

  boolean triggerEnergySaveMode() Java {
     System.out.println(
       "Triggering Energy Saving Mode");
    return true;
  }

  boolean triggerEnergySaveMode() Python {
    print("Triggering Energy Saving Mode")
    return True
  }

  boolean stopMotor() Java {
     System.out.println("Stopping motor");
    return true;
  }

  boolean stopMotor() Python {
    print("Stopping motor")
    return True
  }  

  boolean triggerNormalEnergyMode() Java {
     System.out.println(
       "Triggering Normal Energy Mode");
         return true;
  }

  boolean triggerNormalEnergyMode() Python {
    print("Triggering Normal Energy Mode")
    return True
  }  
  
  boolean waitawhile() Java {
    System.out.println("Waiting");
    return true;
  }

  boolean waitawhile() Python {
    print("Waiting")
    return True
  }  
  
  boolean test() Java {
          System.out.println("Testing");
         return true;
  }

  boolean test() Python {
    print("Testing")
    return True
  }  
}
// @@@skipcppcompile

      

YouTube Video with Additional Explanation

Syntax