Felipe Gaucho's Blog

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let's do it again, using GregorianCalendar

Few days ago I was listening a client about the framework his company was producing for a long time. Tips about the workflow, security and several other common features of a framework. A special feature gave me a déjà vu: the control of holidays in the financial modules. Every financial calculus is based on working days and every framework I've ever seen in my life had also a module for the calculation of workdays range - subtracting holidays, sundays, etc.

These modules are so identical that I've started to think about the need to include that feature in the java.util.GregorianCalendar or some other implementation of the Calendar Interface.

I know APIs should avoid features from specific applications, such as it was well explained in a recent entry of the Eamonn McManus blog. But this special algorithm - the calculus of workdays within a time interval - is so common that I think it should be included as a generic feature in a next review of the class GregorianCalendar.

Everyone who already implemented such feature knows about its functionality: you store a list of holidays, and the Calendar identify the Sundays for you. The algorithm consists in comparing each day of the time interval with the days from that holidays list. Quite simple, but quite repetitive for all system implementation.

One can argue that companies can implement it just once and reuse the algorithm in the new systems. I agree with that, but I also think such obvious algorithm should be part of the Java API as a facility.

I was thinking about a Java Specification Request or just suggest this new feature to the JDK community, but I prefer to listen you first. I'm not sure if there is something already supported by the API (I didn´t find any reference about that) and I also prefer to discuss its utility with you before to go into the formal aspects of a specification request - a sanity check :).

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