Hiding data on a Excel Spreadsheet using POI

I had a requirement where I needed to hide some meta data in Excel Spreadsheet. Instead of using hidden row/columns/cells I used Custom Properties. Custom properties is a map in the Spreadsheet file where you can store key/value data. I found this much safer than hiding the data on the sheets since users could delete/corrupt the data very easily.

Seam parameter as date

When using Seam Gen to setup basic pages from the persistence objects where a primary key is a date or one of the keys in the combined primary key is a date you will run into this error: “value must be a date” This is due to the date converter not working properly when seam is parsing the page parameters. By default it just performs a toString causing the page parameter to be populated as follow:

5×5 LED Cube

The 5×5 LED cube project version 1.0 is working!

I am making use of 4 shift registers 74CH595N to control the 25 columns and 5 P2N2222A NPN Transistor to select a layer. Currently I am writing the cube state for a layer out every 7ms.