Right now under the headless java specification, there is no means for swing components to be sent to a printer. The problem is that a top-level window is required for components to be seen as "showing" and to have valid lightweight peers.
An advanced application programmer can simulate a top-level container, but such a thing is not intuitive (and it took myself, an AWT core programmer, several tries to get it right).
See the suggested fix; this is a new RFE to track the feature.