Creating a submenu in context menu from overridden getActions in Java JHotDraw

问题

I am overriding the getActions method in the Java based framework JHotDraw, an open source project hosted here. The method getActions creates a right click context menu on Figure in the Drawingview. I can correctly add addidtional context menu options using the code below. I need to know how to add a sub menu to the context menu.

@Override
public Collection<Action> getActions(Point2D.Double p) {
  Collection<Action> popupMenu = new ArrayList<Action>();
  popupMenu.add(new AbstractAction("add Context Option 1") {
    public void actionPerformed(ActionEvent event) {
      preformThisMethod("params");
    }
  });
  popupMenu.add(new AbstractAction("add Context Option 2") {
    public void actionPerformed(ActionEvent event) {
      preformThisMethod("params");
    }
  });
  // How to add a sub menu to the context menu?
  return popupMenu;
}

回答1:

Adding submenus is supported.

The class org.jhotdraw.gui.JPopupButton extends JButton to provide the popup menus used throughout the framework. The method add(javax.swing.JMenu submenu) may be used to construct hierarchical submenus. For example, org.jhotdraw.samples.draw.DrawingPanel adds a Zoom submenu to the rightmost popup menu in creationToolbar, along with other miscellaneous editing actions. The method createFontButton() in org.jhotdraw.draw.action.ButtonFactory is another example used to addFontButtonsTo() the editor.

In contrast, right-clicking on the org.jhotdraw.draw.DefaultDrawingView is handled by an instance of javax.swing.JPopupMenu in org.jhotdraw.draw.DelegationSelectionTool, as shown in org.jhotdraw.samples.mini.EditorSample. In particular, the AbstractAction property Actions.SUBMENU_KEY identifies a submenu name. Set DEBUG = true to see the effect. None are presently defined.

来源：https://stackoverflow.com/questions/13312223/creating-a-submenu-in-context-menu-from-overridden-getactions-in-java-jhotdraw