Daniel E. Markle's Blog

A Java Swing user interface I am working on which makes extensive use of a custom JTableModel implementation was failing. In certain instances when my data structure changes, it purges empty cells. If the cursor was left in these cells while this was taking place, the table would become unresponsive, often requiring an application restart to fix.

Watch for issues with setValueAt, which in some cases can be called with invalid values. In particular if the cursor is editing a field, the table is not refreshed until the edit focus leaves the widget even if you try to force it with validate() calls. In my instance the ideal fix was to add checks and do nothing instead of throwing exceptions.

With getValueAt, some table widget types choked on my default of null, which I was returning for invalid cells. Using an empty string instead of null for these invalid cells fixed this problem.

Having just returned from the Central PA Open Source Conference, I found it to be a very informative and useful conference. A wide array of interesting topics in different fields were covered, and there were many items I can apply over the next few months to my own projects.

My favorite session was Hardware and Honeybees, in large part because it showed interesting uses for technology and hardware hacking, something as a software-oriented person I do not see much of. Using cell phone text messages to control electric fences, web cameras to monitor hive status, and inexpensive temperature monitors to find problems were all topics in this interesting talk.

While eating at Neato Burrito today I noticed these delicious looking treats in their dessert bin in front of the cash register.

Labeled Bailout Brownies, they consist of a rich chocolate brownie with gold foil-wrapped chocolate coins adhered to the top with a chocolate glue. While eating, the coins stay on the top until their location is reached, when instead of the coin falling off, a hunk of chocolate comes loose with the coin. After prying the coin loose from the chocolate base, a nice imprint of the coin can be seen in the short period before the chocolate inevitably disappears. In a caricature of the real economy, the shadow of the coin is much more tasty than the chocolate within the coin itself.

A wonderful sweet relief from the stress and woe caused by this trying time.