Notes on ObjectAid

Legend

Creating an object (UML) diagram

In Eclipse's Project Explorer, right-click the parent subdirectory where you would like to create the diagram. You can create the diagram anywhere you wish in the project, it doesn't have to be under src. Choose New → Other then scroll down as shown below.

Then, with it open, just drag .java classes from the Eclipse Project/Package Explorer views and drop them into it. Rearrange, shrink, etc. as desired.

Initial preferences (nearly all are unchecked)

I like to lose most of the ObjectAid baggage. Rather than use the context menu by right-clicking each rectangle in the diagram, I do the tailoring for how I want them to appear in the first place.

Window → Preferences → ObjectAid → ...

Displaying classifiers in diagrams

Please note that there are two ways to affect the appearance in the diagram of a classifier. First, for a new diagram, you can select or deselect elements of what's displayed in the diagram by means of checkboxes. Second, you can configure preferences for ObjectAid™ using Window → Preferences → Class Diagram to determine the defaults you'll see when creating a new diagram. For example, unclicking

• all Attributes checkboxes
• all Operations checkboxes

...in Preferences will cause the class above to be displayed more simply:

...which might be more appropriate or useful in some circumstances. You can also, via the context menu, right-click a classifier in the diagram and remove any of this stuff on the fly.

Clicking and dragging classifiers in diagrams

It's pretty easy to align the boxes, rework or straighten out arrows, etc., just click and drag. One great hint, however, is that if you click a box to select it, then hold down the Shift before then dragging it, it will drag (only) in a straight line!

Using ObjectAid™ to flesh out diagrams

Class hierarchies can be fleshed out by right-clicking on a classifier already in the diagram and choosing Add. You are presented with the following types of additions:

1. All relationships
2. Associated (based on attributes in classifiers)
3. Dependencies (stuff from method arguments and variables)
4. Generalized (inheritance^*)
5. Nested relationships
6. Realized (Java interface implementation)

^* Parent or super classes only. If you wish to add subclasses of a classifier, open Eclipse's Type Hierarchy view and drag them into the diagram from there. To reach this view for a given identifier, right-click on it and choose Open Type Hierarchy. That view will (usually) come up in the same workbench pane as the Project or Package Explorer. You can also open the Type Hierarchy from the diagram itself by right-clicking on the classifier.

Cleaning up diagrams

You may wish to clean up a diagram, perhaps get rid of class variables, methods and arc labels. Some of this has already been covered on this page. This can be done thus:

For class and instance variables and also methods, right-click the classname and choose, here for which operations (methods) to show or not show, but it's the same list for attributes (class and instance variables), one of Package, Private, ... or even None. None turns them off leaving nothing more than a box with the classname in it:

Similarly, some arcs (arrows) will be labeled with names and version numbers. These are easily turned off by right-clicking the arc and toggling off the Show Labels and/or Show Multiplicity items:

Last, it's possible to clean up what's left over using the Options item of the context menu. Right-click on a classname, choose Options and toggle off:

1. Operation Signature —arguments lists on methods
2. Package Name —across the bottom of the box
3. Sterotype —usually <<Java Class>> across the top of the box

As you can see in the last illustration, for the purpose of visualizing the simple, inter-class relationships, my diagram is a lot cleaner and more useful.

Breakage