Currently there is no way to hide the tab bar if only one tab is present. But i think that this would be a pretty cool (optional) feature!

It is possible to call

webTabbedPane.getTabComponentAt(0).setVisible(false);

but that will hide everything, not just the tab bar. Also see this for further information: http://stackoverflow.com/questions/942500/is-there-a-way-to-hide-the-tab-bar-of-jtabbedpane-if-only-one-tab-exists