A View Manager in Vaadin

-
One of the problems I faced early on in developing a Vaadin Application was how to move from one screen to the next.

I managed to find a example pattern which is based on a "View Manager". This object is responsible for maintaining the various screens within the application. At any point you can ask the "Manager" for a previous screen and you can display its contents.

The example I found that uses this pattern is called the "Gas Diary".

The View Manager class itself contains a HaspMap and a Stack. The HashMap contains a string for the name of the view and a Layout. The Stack contains a Layout.

In the Gas Diary Main Application the Login Screen is "switched" to via this process.



        setMainWindow(mainWindow);
        
        viewManager = new ViewManager(mainWindow);
        
        // Create the login screen
        viewManager.switchScreen(LoginScreen.class.getName(), new LoginScreen());


This method has worked for me and I suspect it will work for you.
No idea why this isn't documented anywhere in the "official" Vaadin documentation.

Would be nice... 

Comments

Post a Comment

Popular posts from this blog

Vaadin - GRID Component

-
Image
Introduction Vaadin 7.4 was recently released and it includes a new component called the GRID . It represents a 'Spreadsheet" type model from a UI perspective, however I think it lacks a lot of features you would expect from this type of component. Maybe this component will evolve over time and it will begin to have the functions that you expect from a spreadsheet. ( note: there is a commercial add on called the Spreadsheet from Vaadin ) Use Case The use case I am demonstrating below is a simple grid showing projected sales of Widgets over a five year period. Creation Creating a Grid is very simple and you have numerous options for sizing on the page. In the example below I setting it across the page. The Grid rows can be selected for editing, you can select single or multiple rows in a single action. myGrid = new Grid(); myGrid.setSizeFull(); myGrid.setSelectionMode(SelectionMode.SINGLE); Container Backing Similar to many other Vaadin componen
Read more

Connecting a Vaadin SQL Container to a Combo Box

-
It must be me. But I spent a lot of time trying to figure out how to connect a database table implemented as a Vaadin SQL Container to a Vaadin Combo Box. It seems such a simple concept. Anyway, here was my requirement. I needed a combo box to contain a list of Australia suburbs. The user would select a suburb which would filter the results in a table on the screen. My database table was very simple. A id field ( which was the primary key ) and a name field which contained the suburb name. The code for the SQL Container was simple. TableQuery q = new TableQuery("suburb", connectionPool); suburbContainer = new SQLContainer(q); Now code to establish the combo box and links to the SQL Container.   ComboBox suburbCB = new ComboBox();  suburbCB.addItem("");  suburbCB.setCaption("Filter by Suburb");  suburbCB.setContainerDataSource(app.getDatabase().loadSuburbs());  suburbCB.setItemCaptionPropertyId("name");  suburbCB.setItemC
Read more

Web Cam and Vaadin

-
A very interesting Web Cam Add On is available from the Vaadin Add On site . Here is a simple recipe for making it work. Create a split panel and add the Web Cam to the left hand side of the panel. splitPanel = new HorizontalSplitPanel(); splitPanel.setSizeFull(); VerticalLayout detailsLayout = new VerticalLayout(); detailsLayout.setSpacing(true); detailsLayout.setSizeFull(); // Create the webcam and assign a receiver. final Webcam webcam = new Webcam(); webcam.setWidth("600px"); detailsLayout.addComponent(webcam); detailsLayout.setComponentAlignment(webcam, Alignment.TOP_LEFT); Create a receiver which creates a temporary file with a jpeg extension. webcam.setReceiver(new Upload.Receiver() { @Override public OutputStream receiveUpload(String filename, String mimeType) { try { targetFile = File.createTemp
Read more