Friday, November 21, 2014

Custom Java Metrics in Eclipse

Recently, a relative inquired if I could provide a tool to calculate custom metrics for java code, so I began search and found an old, but open source plugin for eclipse that does just exactly that- calculate metrics without doing any fluffy stuff.
I took its source code and provided it on github.

I had to do minor changes to make it working quickly, which was to use only the metrics table prospective and hide the views not in use.

Here, the metrics need to be provided with 2 essential things:
  1. The name of metric in the plugin.xml file (which is read by the plugin in the list of metrics to calculate)
  2. Name of the calculator file, which contains the logic used in calculating a specific metric value

The required custom metrics were outlined in a paper that discussed about quality of object oriented design and was academic in nature, so the nature of metrics created is quite simple.

For instance, the metric 'Inheritance Ratio' took the form of following tag in plugin.xml

    name="Inheritance Ratio"

and also mapped its logic via the calculator tag:
    name="Inheritance Ratio"

Next, there is need of simply creating this calculator file and overriding the calculate method. Another thing is to create constants like INHR (in this example) by which the metric and its calculator may communicate during runtime.

So, by piggybacking on this application, I was easily able to provide the metrics tool without worrying anything about the UI and source code management. I plan to finish this quickly and then improve it as per suggestions, which are always welcome!

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