NB: How to create a context-aware submenu

Last time I blogged about “How create a context sensitive action with a submenu in the project-view?” [1].  Now there was an additional requirement to be fulfilled: The submenu should be only enabled, when exactly two project nodes are selected. Only if this condition is true, the submenu items should be displayed.

Thanks to the help of Jean-Marc Borer a solution can be provided too.

@ActionID(
        category = "MyActions",
        id = "de.markiewb.netbeans.sample.ContextAwarePopupAction"
)
@ActionRegistration(
        displayName = "#CTL_ContextAwarePopupAction", lazy = false
)
@ActionReferences({
    @ActionReference(path = "Projects/Actions")
})
@Messages("CTL_ContextAwarePopupAction=I am a context-aware submenu")
public final class ContextAwarePopupAction extends AbstractAction implements ActionListener, Presenter.Popup {

    private final Lookup.Result<Project> result;
    private final transient LookupListener lookupListener;

    public ContextAwarePopupAction() {
        putValue(NAME, Bundle.CTL_ContextAwarePopupAction());
        //disabled by default - at loading time
        setEnabled(false);
        //create an action, which is only enabled when exactly 2 projects are selected
        result = Utilities.actionsGlobalContext().lookupResult(Project.class);
        this.lookupListener = new LookupListener() {

            @Override
            public void resultChanged(LookupEvent ev) {
                final Runnable runnable = new Runnable() {

                    @Override
                    public void run() {
                        int s = result.allInstances().size();
                        ContextAwarePopupAction.this.setEnabled(s == 2);
                    }
                };
                // to make sure that it will be executed on EDT
                if (EventQueue.isDispatchThread()) {
                    runnable.run();
                } else {
                    SwingUtilities.invokeLater(runnable);
                }
            }
        };
        result.addLookupListener(WeakListeners.create(LookupListener.class, this.lookupListener, result));
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        //NOP
    }

    @Override
    public JMenuItem getPopupPresenter() {
        JMenu main = new JMenu(this);
        List<? extends Action> actionsForPath = Utilities.actionsForPath("Actions/MyActions/SubActions");
        for (Action action : actionsForPath) {
            main.add(action);
        }
        return main;
    }
}

The most important part of the popup action is to emulate a context-aware action using a lookup listener.

The updated sample code can be found at https://github.com/markiewb/nb-api-samples/tree/master/SubmenuWithContextSensitiveAction. The entry of the offical developer FAQ at http://wiki.netbeans.org/DevFaqActionNodePopupSubmenu has also been updated.

[1] https://benkiew.wordpress.com/2015/09/01/nb-how-to-create-a-context-sensitive-action-within-a-submenu/

 

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