Extending the Watch example to support MIDP required surprisingly few changes. In fact, more changes were made because of minor problems noticed in the initial code than because of MIDP.

One such problem was an area that we decided not to support initially, because of the lack of use: how should an alarm react when the clock time is changed. We had built metamodel support for this (alarms have a property to say whether they are dependent on local time: true for an alarm clock, false for a countdown timer), but had left out the implementation in the framework classes as being not worth the effort. “After all, who is likely to lug a PC around to use our watch application’s alarm?” we thought. How short-sighted we were!