java.util.NoSuchElementException unregistering a TransitionEndListener

[hekailiang]

java.util.NoSuchElementException unregistering a TransitionEndListener

[claudio-rosati]

The listeners I've added are the following:

public void attachListenersToFSM () {
  fsm.addStartListener(startListener);
  fsm.addStateMachineExceptionListener(stateMachineExceptionListener);
  fsm.addStateMachineListener(stateMachineListener);
  fsm.addTransitionBeginListener(transitionBeginListener);
  fsm.addTransitionCompleteListener(transitionCompleteListener);
  fsm.addTransitionDeclinedListener(transitionDeclinedListener);
  fsm.addTransitionEndListener(transitionEndListener);
  fsm.addTransitionExceptionListener(transitionExceptionListener);
}

removed in the following order:

public void detachListenersToFSM () {
  fsm.removeTransitionExceptionListener(transitionExceptionListener);
  fsm.removeTransitionEndListener(transitionEndListener); // <== Exception thrown
  fsm.removeTransitionDecleindListener(transitionDeclinedListener);
  fsm.removeTransitionCompleteListener(transitionCompleteListener);
  fsm.removeTransitionBeginListener(transitionBeginListener);
  fsm.removeStateMachineListener(stateMachineListener);
  fsm.removeStateMachineExceptionListener(stateMachineExceptionListener);
  fsm.removeStartListener(startListener);
}

[hekailiang]

It would be helpful if you can provide a runnable test case to reproduce the issue.

[claudio-rosati]

Here a test case: it's a mixture of my code and your example... but it works throwing the exception.
Java 8 is required for the lambda expressions.

import org.squirrelframework.foundation.fsm.StateMachine;
import org.squirrelframework.foundation.fsm.StateMachineBuilderFactory;
import org.squirrelframework.foundation.fsm.UntypedStateMachine;
import org.squirrelframework.foundation.fsm.UntypedStateMachineBuilder;
import org.squirrelframework.foundation.fsm.annotation.StateMachineParameters;
import org.squirrelframework.foundation.fsm.impl.AbstractUntypedStateMachine;


public class QuickStartSample {

    private static final StateMachine.StartListener startListener = e -> started(e);
    private static final StateMachine.StateMachineExceptionListener stateMachineExceptionListener = e -> stateMachineException(e);
    private static final StateMachine.StateMachineListener stateMachineListener = e -> stateMachineEvent(e);
    private static final StateMachine.TransitionBeginListener transitionBeginListener = e -> transitionBegin(e);
    private static final StateMachine.TransitionCompleteListener transitionCompleteListener = e -> transitionComplete(e);
    private static final StateMachine.TransitionDeclinedListener transitionDeclinedListener = e -> transitionDeclined(e);
    private static final StateMachine.TransitionEndListener transitionEndListener = e -> transitionEnd(e);
    private static final StateMachine.TransitionExceptionListener transitionExceptionListener = e -> transitionException(e);

    public static void main ( String[] args ) {

        UntypedStateMachineBuilder builder = StateMachineBuilderFactory.create(StateMachineSample.class);

        builder.externalTransition().from("A").to("B").on(FSMEvent.ToB).callMethod("fromAToB");
        builder.onEntry("B").callMethod("ontoB");

        UntypedStateMachine fsm = builder.newStateMachine("A");

        attachListenersToFSM(fsm);
        fsm.fire(FSMEvent.ToB, 10);
        detachListenersFromFSM(fsm);

        System.out.println("Current state is " + fsm.getCurrentState());

    }

    public static void attachListenersToFSM ( UntypedStateMachine fsm ) {
        fsm.addStartListener(startListener);
        fsm.addStateMachineExceptionListener(stateMachineExceptionListener);
        fsm.addStateMachineListener(stateMachineListener);
        fsm.addTransitionBeginListener(transitionBeginListener);
        fsm.addTransitionCompleteListener(transitionCompleteListener);
        fsm.addTransitionDeclinedListener(transitionDeclinedListener);
        fsm.addTransitionEndListener(transitionEndListener);
        fsm.addTransitionExceptionListener(transitionExceptionListener);
    }

    public static void detachListenersFromFSM ( UntypedStateMachine fsm ) {
        fsm.removeTransitionExceptionListener(transitionExceptionListener);
        fsm.removeTransitionEndListener(transitionEndListener);
        fsm.removeTransitionDecleindListener(transitionDeclinedListener);
        fsm.removeTransitionCompleteListener(transitionCompleteListener);
        fsm.removeTransitionBeginListener(transitionBeginListener);
        fsm.removeStateMachineListener(stateMachineListener);
        fsm.removeStateMachineExceptionListener(stateMachineExceptionListener);
        fsm.removeStartListener(startListener);
    }

    private static void started ( StateMachine.StartEvent e) {
    }

    private static void stateMachineEvent ( StateMachine.StateMachineEvent e) {
    }

    private static void stateMachineException ( StateMachine.StateMachineExceptionEvent e) {
    }

    private static void transitionBegin ( StateMachine.TransitionBeginEvent e) {
    }

    private static void transitionComplete ( StateMachine.TransitionCompleteEvent e) {
    }

    private static void transitionDeclined ( StateMachine.TransitionDeclinedEvent e) {
    }


    private static void transitionEnd (StateMachine.TransitionEndEvent e) {
    }

    private static void transitionException (StateMachine.TransitionExceptionEvent e) {
    }

    @StateMachineParameters( stateType = String.class, eventType = FSMEvent.class, contextType = Integer.class )
    static class StateMachineSample extends AbstractUntypedStateMachine {

        protected void fromAToB ( String from, String to, FSMEvent event, Integer context ) {
            System.out.println("Transition from '" + from + "' to '" + to + "' on event '" + event + "' with context '" + context + "'.");
        }

        protected void ontoB ( String from, String to, FSMEvent event, Integer context ) {
            System.out.println("Entry State \'" + to + "\'.");
        }

    }

    enum FSMEvent {

        ToA, ToB, ToC, ToD

    }

}

[hekailiang]

I just fixed the issue. Please try latest snapshot version.

[claudio-rosati]

I've tested the latest snapshot and it is working correctly.
Thank you.