alice-teacher Alice 2 "While the world is running" event

[Vanderhyde, James]

In Alice 2, you can right-click on the “When the world starts” event and change it to “While the world is running.” I’m not sure why this feature is useful, but it doesn’t seem to work completely. If you put something in the “End” portion of this event, when you Play the animation and then Stop it (or close the window), you get the Queen reporting a NullPointerException. (See attached screenshot.)

I’m not sure what the correct behavior should be. I would like it to do the thing I said in the event before the window closes, but then arbitrary user code could generate an infinite loop and make the window impossible to close. Maybe hitting Stop during the End event could stop it for good, so you have to hit Stop at most twice to close the window.

Or maybe just remove the End option in the event, so we don’t see the error.

James
—
James Vanderhyde
Assistant Professor, Computer Science
Program Director, Master of Applied Computer Science
Saint Xavier University
3700 W. 103rd St.
Chicago, IL 60655
773-298-3454
[cid:6F5B8DDC-40B3-47FB-A749-0C811FAAE39F at SXU.local][cid:4E56EC2F-EAFC-44C6-8908-B5976C3142CE at SXU.local]
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