Question

I know there are many questions concerning this topic but after reading them all I’m even more confused.

I have an application that manages contacts. There are three pages:

• Add contact
• Show contacts
• Modify contact

And now I have no idea what structure to give to my project: should I create three different modules? if so, what would be the best package structure? and how would I call other modules within a page? for example, from the ‘add contact’ page there should be a button to the ‘show contacts’ page, and from this one there should be button/links to ‘modify contact’ and ‘add contact’.

would it be enough to add this line to the corresponding buttons event handlers?

Window.Location.assign("showcontacts.html");

(or just create a link to “showcontacts.html” if it’s the case)?

Answer 1

To allow multiple pages to be selectively displayed within a single module, I use one of two techniques:

1. use a SimplePanel or one of its
   derivatives (e.g. LazyPanel,
   ScrollPanel).Use setWidget to change
   the page. Each “page” is a widget.
   For example, I am doing a project
   with a menubar. When “Home” menuitem
   is clicked, the menu command
   replaces the body of the simplepanel
   by setting its widget to the Home
   widget. Likewise for login, etc
   menuitems.

   A SimplePanel allows only one widget.
   Therefore, you do not addWidget to it but setWidget to it.

2. use tab. Either TabLayoutPanel or
   TabPanel. I prefer using the
   TabLayoutPanel. You have to meticulously
   set/design the CSS for TabLayoutPanel, otherwise
   you would only see a blob of text hanging around.

I also try to encapsulate a “page” widget in a lazypanel (which is a derivative of a simple panel. That will prevent instantiation of any pages that may not be used in a module with a large number of “pages”.

GWT is indeed suitable for ui presentation with multiple pages. In fact, one of the advantages of GWT over JSP is that you can change a page without a browser refresh/fetch flicker – one of the extremely strong reasons why you would want to use GWT for a web app with multiple pages.