Poseidon provides a slick dialog to assist with the importation of source code. You can save any changes you make to the settings, such as modeling Java attributes as UML associations, by clicking the 'Apply' button in the lower right section of the dialog.
Several options are available when importing code:
General Tab
Descend directories recursively - Easily add all files below the selected directory
Skip CVS and SCCS directories - Ignore version control files
Java Tab
Java attributes modeled as - Select either attributes or associations
Arrays are modelled - Select either as data types or with a multiplicity of 1..n
Import Classpath - Add classpaths by clicking the 'Add' button and navigating to the classpath in the browser that opens automatically.
Should the import fail because needed files have not been located, an error dialog will appear. If you would like to continue without adding to the classpath and create dummy classes instead, click 'Yes'. To return to the previous dialog and add the necessary files to the classpath, click 'No'.
Once the import has begun, a dialog will appear asking if you would like to generate diagrams. A tree of the project is also presented, so that you can choose which packages and classes you would like to include in the diagrams. By default, any packages that contain new classes are automatically selected.
MDL Import Tab
The MDL Import tab is used to import diagrams saved to the Rational Rose format.
Scale down diagrams to [%] - Automatically resizes diagrams for easier readability
Show classifiers' packages - Hides or displays the package of a classifier
Create no diagrams - Import just the elements, or import the elements and create all diagrams
Skip View Root Notes - Does not import the view root notes
Here is an example of what an imported Java class looks like in the Navigation Pane and in the Diagram pane, as well as showing a bit of the source code: