I say *UML* because it may not be what I'm looking for.

I seek a java library that can take a set of objects and connections
between those objects and display them connected in a UI, preferably in
Swing (although image files would be fine I suppose.)

Specifically, I have modeled hardware devices as objects that have any
number of inputs and outputs, where the output of one hardware device
would connect to the input of another hardware device.  Given a set of
these devices and connections between them, I would like to give this
information to an API and have it display it for me in Swing, much like
the way UML diagrams can have connections between objects.  But I'm not
sure that UML is the right way to go (maybe it is).

Imagine using MS Visio and creating boxes that have connections between
them, and you can move them around and the connections stay together.
That is basically what I'm looking for.

DOes anybody know of a Java based tool that can do this for me?  Or
should I adapt some tool like a UML creator to do this.  I'm not even
sure where to start looking or what this might be called.

Thanks.