Automatically generate Java code based on existing fields in a class

Question

Scenario

I'm working with a Java model built from scratch in Eclipse. What's important in this model is that we save our output to MATLAB (.mat) files. I constantly add new features, which require new fields that in turn will have to be exported to the .mat file at every iteration. Upon restarting a crashed simulation, I might have to import the .mat file. To export or import my .mat file I use JMatIO.

For example, if I would add a new field rho_m (a simple double) to my class CModel, I have to add to my Save() method:

mlModel.setField("rho_m", new MLDouble(null, new double[] {rho_m}, 1));

And to my Load() method:

rho_m = ((MLDouble)mlModel.getField("rho_m")).getReal(0);

Note that even though rho_m is a double, it needs to be treated as a double[] in JMatIO. This probably has something to do with MATLAB being orientated towards matrices and matrix operations.

Problem

Instead of doing this manually (prone to errors, annoying to maintain) I would like to automate this procedure. Ideally, I would like my IDE to detect all the fields in CModel and write the code based on the field's name and type. Is there any way to do this in Java/Eclipse?

Ideas so far

I have no formal training in low-level programming languages (yes, Java is low-level to me) and am still relatively new to Java. I do have some experience with MATLAB. In MATLAB I think I could use eval() and fieldnames() in a for loop to do what I mentioned. My last resort is to copy-paste the Java code to MATLAB and from there generate the code using a huge, ugly script. Every time I want to make changes to the model I'd rerun the MATLAB script.

Besides that idea I've found terms like UML, but do not have the background knowledge to figure out if this is what I'm looking for or not.

Any help, even if it's just a small push in the right direction, is greatly appreciated. Let me know if I need to further clarify anything.

Little update regarding my solution: I looked into the Eclipse plugins and they seemed either too complicated (collaboration options, paid versions, etc) or outdated. I ended up writing my own "code generator" in MATLAB. MATLAB reads the file, using regexp it filters out the comments, names and types, then writes the source code that can be copy-pasted into my model's Save and Load methods. — Tomas
– Tomas, Commented Aug 9, 2012 at 4:30

Rui Curado · Accepted Answer · 2012-08-08 22:39:47Z

Looking at your scenario, you are doing model-driven code generation, that is, you have a model and want to get some code generated according to your current model. Therefore, you need a model-driven code generator.

I lead the ABSE/AtomWeaver project, so I'll outline what you can do to get what you want using AtomWeaver (There are however other solutions like MetaEdit+, XText or Eclipse's own GMT/EMF sub-system).

AtomWeaver is an IDE where you can build a model and generate code from that model. You can change your model as many times you want and hit the "Generate" button to get an updated version of your code. ABSE is the name of the modeling method.

We don't need to go into details, but essentially ABSE follows a "building-block" approach. You create a Template that represents a feature or concept of your model. Then, you can associate a mini-code generator just to that concept. You can then "instantiate" and combine those building blocks to quickly build your models. Variables increase the flexibility of your models.

You can also change your models, or add new features ("blocks") and generate again. The generators are built using the Lua programming language, a very simple language with C-Like syntax.

The best way to understand the ABSE development method and the AtomWeaver IDE is to download the IDE and see the samples or try the tutorials. And yes, you can use AtomWeaver for free.

Thanks for this explanation. So the buzz word is model driven code generator. Since I'm already working in Eclipse I'll take a look at GMT and EMF

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