//  [java]
    protected double acceptStep(final AbstractStepInterpolator interpolator,
                                final double[] y, final double[] yDot, final double tEnd)
        throws MathIllegalStateException {
            double previousT = interpolator.getGlobalPreviousTime();
            final double currentT = interpolator.getGlobalCurrentTime();
            resetOccurred = false;
            if (! statesInitialized) {
                for (EventState state : eventsStates) {
                    state.reinitializeBegin(interpolator);
                }
                statesInitialized = true;
            }
            final int orderingSign = interpolator.isForward() ? +1 : -1;
            SortedSet<EventState> occuringEvents = new TreeSet<EventState>(new Comparator<EventState>() {
                public int compare(EventState es0, EventState es1) {
                    return orderingSign * Double.compare(es0.getEventTime(), es1.getEventTime());
                }
            });
            for (final EventState state : eventsStates) {
                if (state.evaluateStep(interpolator)) {
                    occuringEvents.add(state);
                }
            }
            while (!occuringEvents.isEmpty()) {
                final Iterator<EventState> iterator = occuringEvents.iterator();
                final EventState currentEvent = iterator.next();
                iterator.remove();
                final double eventT = currentEvent.getEventTime();
                interpolator.setSoftPreviousTime(previousT);
                interpolator.setSoftCurrentTime(eventT);
                interpolator.setInterpolatedTime(eventT);
                final double[] eventY = interpolator.getInterpolatedState();
                currentEvent.stepAccepted(eventT, eventY);
                isLastStep = currentEvent.stop();
                for (final StepHandler handler : stepHandlers) {
                    handler.handleStep(interpolator, isLastStep);
                }
                if (isLastStep) {
                    System.arraycopy(eventY, 0, y, 0, y.length);
                    return eventT;
                }
                if (currentEvent.reset(eventT, eventY)) {
                    System.arraycopy(eventY, 0, y, 0, y.length);
                    computeDerivatives(eventT, y, yDot);
                    resetOccurred = true;
                    return eventT;
                }
                previousT = eventT;
                interpolator.setSoftPreviousTime(eventT);
                interpolator.setSoftCurrentTime(currentT);
                if (currentEvent.evaluateStep(interpolator)) {
                    occuringEvents.add(currentEvent);
                }
            }
            interpolator.setInterpolatedTime(currentT);
            final double[] currentY = interpolator.getInterpolatedState();
            for (final EventState state : eventsStates) {
                state.stepAccepted(currentT, currentY);
                isLastStep = isLastStep || state.stop();
            }
            isLastStep = isLastStep || Precision.equals(currentT, tEnd, 1);
            for (StepHandler handler : stepHandlers) {
                handler.handleStep(interpolator, isLastStep);
            }
            return currentT;
    }