Why do I keep getting this NotSerializedException:
WARNING: Error in serialization of the application: Class com.example.application_lifecycle_chapter_4_7.ApplicationLifecycleUI$Servlet must implement serialization.
Dec 10, 2014 12:55:05 PM org.apache.catalina.session.StandardSession doWriteObject
WARNING: Cannot serialize session attribute com.vaadin.server.VaadinSession.AppLifeServlet for session …
Here is the code for the UI (which contains the static Servlet class):
@Theme("application_lifecycle_chapter_4_7")
@Push // setting this UI as pushable
public class ApplicationLifecycleUI extends VaadinAbstractMappableUI {
/**
*
*/
private static final long serialVersionUID = 1L;
@WebServlet(value = {"/AppLife/*", "/VAADIN/*"}, asyncSupported = true)
@VaadinServletConfiguration(productionMode = false, ui = ApplicationLifecycleUI.class)
public static class Servlet extends VaadinServlet
implements SessionInitListener, SessionDestroyListener, BootstrapListener {
/**
*
*/
private static final long serialVersionUID = 1L;
// Handling Session Initialization and Destruction
@Override
protected void servletInitialized() throws ServletException {
super.servletInitialized();
getService().addSessionInitListener(this);
getService().addSessionDestroyListener(this);
}
@Override
public void sessionInit(SessionInitEvent event) throws ServiceException {
// Do session start stuff here
// Adding the bootstrap listener to the Session
VaadinSession.getCurrent().addBootstrapListener(this);
}
@Override
public void sessionDestroy(SessionDestroyEvent event) {
// Do session end stuff here
}
// Customizing the Loader Page
@Override
public void modifyBootstrapFragment(BootstrapFragmentResponse response) {
}
@Override
public void modifyBootstrapPage(BootstrapPageResponse response) {
}
}
@SuppressWarnings("serial")
@Override
protected void init(VaadinRequest request) {
final VerticalLayout layout = new VerticalLayout();
layout.setMargin(true);
setContent(layout);
Button button = new Button("Click Me");
button.addClickListener(new Button.ClickListener() {
public void buttonClick(ClickEvent event) {
layout.addComponent(new Label("Thank you for clicking"));
}
});
layout.addComponent(button);
Button logoutButton = new Button("Logout");
logoutButton.addClickListener(e -> {
getPage().setLocation("/Application_Lifecycle_Chapter_4.7/VAADIN/logout.html");
getSession().close();
});
// Setting a faster heartbeat
//setPollInterval(3000);
layout.addComponent(logoutButton);
}
}Is it because of the Button.ClickListener inside the init() UI method? Then why the exception says “ApplicationLifecycleUI$Servlet must implement serialization” and not “ApplicationLifecycleUI must implement serialization”?
Shouldn’t Vaadin handle serialization automatically as is said in the Book?
Anyway, how can I get rid of this exception?
Thank you for the attention!