[java] last day of month calculation

I am having issues with the calculation of when the next Last Day of the Month is for a notification which is scheduled to be sent.

Here is my code:

RecurrenceFrequency recurrenceFrequency = notification.getRecurrenceFrequency();
Calendar nextNotifTime = Calendar.getInstance();

This is the line causing issues I believe:

nextNotifTime.add(recurrenceFrequency.getRecurrencePeriod(), 
                  recurrenceFrequency.getRecurrenceOffset());

How can I use the Calendar to properly set the last day of the next month for the notification?