vaadin子菜单添加问题

Question

您好，我正在使用导航窗口和类视图为我们的应用程序创建菜单栏，它工作正常，但是当我在菜单栏中添加子菜单时，它显示错误，说

SEVERE: Terminal error:
java.lang.IllegalStateException: Composition root must be set to non-null value before the com.vaadin.incubator.spring.ui.Reference2 can be painted
    at com.vaadin.ui.CustomComponent.paintContent(CustomComponent.java:125)

我的代码就像

    for (final Class viewClass : new Class[] { Trade.class, Position.class,
            Cash.class, Recon.class, Price.class, Accounting.class,
            Reference.class, Report.class, }) {
        navigator.addView(viewClass.getSimpleName(), viewClass);

        if (viewClass.getSimpleName().equals("Price")) {
            MenuBar.MenuItem Price = menu.addItem("Price", null);

            for (final Class viewClasssubmenu : new Class[] {
                    PriceActivity.class, ViewPrice.class, }) {
                navigator.addView(viewClasssubmenu.getSimpleName(),
                        viewClasssubmenu);
                Price.addItem(viewClasssubmenu.getSimpleName(),
                        new MenuBar.Command() {

                            public void menuSelected(MenuItem selectedItem) {
                                // TODO Auto-generated method stub

                                navigator.navigateTo(viewClasssubmenu);

                            }
                        });

            }

        } else if (viewClass.getSimpleName().equals("Recon")) {
            if (viewClass.getSimpleName().equals("Recon")) {
                MenuBar.MenuItem Recon = menu.addItem("Recon", null);

                for (final Class viewClasssubmenu : new Class[] {
                        Recon1.class, Recon2.class, }) {
                    navigator.addView(viewClasssubmenu.getSimpleName(),
                            viewClasssubmenu);
                    Recon.addItem(viewClasssubmenu.getSimpleName(),
                            new MenuBar.Command() {

                                public void menuSelected(
                                        MenuItem selectedItem) {
                                    // TODO Auto-generated method stub

                                    navigator.navigateTo(viewClasssubmenu);

                                }
                            });

                }
            }
        } else if (viewClass.getSimpleName().equals("Reference")) {
            if (viewClass.getSimpleName().equals("Reference")) {
                MenuBar.MenuItem Reference = menu
                        .addItem("Reference", null);

                for (final Class viewClasssubmenu : new Class[] {
                        Reference1.class, Reference2.class, }) {
                    navigator.addView(viewClasssubmenu.getSimpleName(),
                            viewClasssubmenu);
                    Reference.addItem(viewClasssubmenu.getSimpleName(),
                            new MenuBar.Command() {

                                public void menuSelected(
                                        MenuItem selectedItem) {
                                    // TODO Auto-generated method stub

                                    navigator.navigateTo(viewClasssubmenu);

                                }
                            });

                }
            }
        } else {

            menu.addItem(viewClass.getSimpleName(), new MenuBar.Command() {

                public void menuSelected(MenuItem selectedItem) {

                    navigator.navigateTo(viewClass);

                }

            });
        }
    }

    return w;
}

任何人都可以帮助我在导航类视图中如何添加子菜单项？如果你给我提供一个例子，这对我来说会有很大的帮助。

Answer 1

这可能与菜单无关。该错误表明您扩展了一个 CustomComponent（即 Vaadin 语言中的“复合”），但未设置组合根组件。也许这是您的视图类之一？

无论如何，您应该在组件的构造函数中设置它，以确保它在渲染时存在。有关详细信息和示例，请参阅此： http://vaadin.com/book/-/页面/components.customcomponent.html