The Apache POI project provides a free open-source library for creating, reading and manipulating Microsoft Office documents. The functionality for working with Excel files is pretty mature and is quite feature-complete.

Lately, I was confronted with a problem concerning formula evaluation. I had a pre-existing Excel template file that had some cells with placeholder texts. These texts are replaced with number values available at runtime. The result is saved as a new file. This works great with POI until a cell with a placeholder text is used within a formula of another cell. When looking at the template, Excel then obviously complains about the data type of the values used within the formula.

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QDox is a library which allows you to parse a java source file and extract instance variables, methods and even JavaDoc tags from it. Quite some time ago, I had used QDox for a little tool that generates implementation source code for java beans. When writing java bean sources, you usually have to write the same code template again and again for every single bean property. Each time, the template has to include an instance variable, a getter and a setter method and a constant for the property name.

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