Generate Java Code

One common action one want to perform is to generate the Java code that corresponds to a model. It is often the last part of performing Model Driven Engineering. It is also named, the Forward Engineering.

The Moose platform includes a tool to perform such an action, it is named FAMIX2Java. In this page, you will learn how to install the tool and generate Java code based on a Famix Java model pre-loaded from a file, and generated with VerveineJ.


To install FAMIX2Java, first, start your Moose image. Then, in a playground (Browse>Playground) perform the following script:

Metacello new
  githubUser: 'moosetechnology' project: 'FAMIX2Java' commitish: 'v5' path: 'src';
  baseline: 'Famix2Java';

This will install the package Famix2Java in which we will find the code of the exporter.

Export the code

Once you have loaded the project, it is possible to regenerate the Java project based on the model. To do so, you only have to execute

FAMIX2JavaVisitor new
    rootFolder: 'D:\exported' asFileReference;
    export: model.

Note that since FamixJava is a high-level meta-model (not representing the code inside a method), it will not be able to regenerate the code inside the method, but only the structural part. However, if you have set a root folder (see Import model), and not modified that much the model, the exporter will retrieve the code of the method to export based on the sources. If you need to modify the code of methods, see you next section :smile:


Example exporting custom-made model

You might want to use the exporter capabilities without importing a real model first, but by creating yours.

To do so, you can create a simple model and give it to the exporter. For instance, the code bellow can be use to generate a class named MyClass with one method and one attribute in a package named fr.

"Create a dummy model"
model := FamixJavaModel new.

"Create a package"
frPackage := model newPackageNamed: 'fr'.

"Create a class"
class := model newClassNamed: 'MyClass'.
frPackage addType: class.

javaPackage := model newPackageNamed: 'java'.
javaPackage isStub: true.
langPackage := model newPackageNamed: 'lang'.
langPackage isStub: true.
javaPackage addChildEntity: langPackage.

stringType := model newClassNamed: 'String'.
stringType isStub: true.
langPackage addType: stringType.

"Add an attribute to the class"
classAttribute := model newAttributeNamed: 'myAttribute'.
classAttribute declaredType: stringType.
class addAttribute: classAttribute .

"Add primitive void type"
primitiveVoid := model newPrimitiveTypeNamed: 'void'.

"Add a method to the class"
classMethod := model newMethodNamed: 'myMethod'.
classMethod isPublic: true.
classMethod declaredType: primitiveVoid.
class addMethod: classMethod .

"Export the model"
FAMIX2JavaVisitor new
  rootFolder: 'D:\exported' asFileReference;
  export: model.

The code is exported in the defined rootFolder, here it is under the folder D:\exported.

Export only part of the model

For some reason, you might not want to export the full model but only part of it. We give here examples of how to do it.

Export only a class string

It is also possible to use the exporter to generate only the class code (or method, attribute, and so on). To do so you only have to change the last lines of the script that perform the export. Considering the export the model example, replace the last lines with the following:

visitor := FAMIX2JavaVisitor new.
String streamContents: [ :stream |
  visitor currentStream: stream.
  class accept: visitor ]

In this example, String streamContents: is used to create a write stream to populate a String. You can also modify this line to export in a specific file, or any other stream API.

Export method code

You might want to modify the code inside method and export it. This is not part of the FamixJava exporter project, however, the Moose platform includes two other projects that can help you.

First, you should check FAST-Java which allows one to represent the code of a method, modify it, and regenerate it. Second, if you want to use both FAST-Java, and Famix, you can have a look at Carrefour which brings together the two world.