JPopupMenuの取得を親に委譲

JScrollPane scroll = new JScrollPane(table);
scroll.setComponentPopupMenu(new TablePopupMenu());
// scroll.getViewport().setInheritsPopupMenu(true); // JDK 1.5
table.setInheritsPopupMenu(true);
// table.getTableHeader().setInheritsPopupMenu(true);

// ...
private class TablePopupMenu extends JPopupMenu {
  private final Action deleteAction = new DeleteAction("delete", null);
  private final Action createAction = new CreateAction("add", null);

  public TablePopupMenu() {
    super();
    add(createAction);
    addSeparator();
    add(deleteAction);
  }

  @Override public void show(Component c, int x, int y) {
    deleteAction.setEnabled(table.getSelectedRowCount() > 0);
    super.show(c, x, y);
  }
}