What is the best way to manage application screens in SWT?

Question

I'm creating a standalone SWT desktop application that has around 10 different screens (few wizards, help, forms, etc). Some elements on screen don't change at all (like header, background, etc) and there is a working area that changes depending on what is clicked, etc.

What is the best way to manage application screens? Do I need to create all screen at startup and then show/hide them depending on what is clicked? Or do I need to create those screens dynamically?

Also, I couldn't find any way to show/hide a Composite, do I need to dispose it and then create again?

What is the best practice? I'm new to SWT developing outside of Eclipse so any help would be beneficial.

Answer 1

Deciding whether to create screens up front or creating them the first time they need to be displayed is a decision that needs to be made on a per application basis. If there is a good chance that all the screens are going to need to be used on a particular application run and the number of screens is low (10 screens is relatively low) then you may want to create them at application startup so the UI is snappier once the application loads.

If you use bindings then you may need to come up with a dispose strategy (even if you only dispose the bindings) so you don't have too many events flying around.

Control has a setVisible(boolean) method (and Composite inherits from Control) which you can use to show and hide a component. Note this will only prevent the composite from being shown on the screen, the layout manager will still allocate a blank space for it. Many SWT layouts have a way to exclude a control from the layout which will get rid of the blank space. For example if you are using GridLayout then you would set the exclude variable on you GridData object to true when you hide that control.

Another option is to use StackLayout. This lets you stack a bunch of Composites on top of each other and then choose which on is on top. This might be a good fit for you if you have static areas plus a working area like you described. I would put the header, footer, and an empty composite with a StackLayout in a class file. I would then put each screen that will be displayed in the working area in their own classes. You can either have these screen classes extend Composite and then set up themselves in the constructor or you can use a factory method to setup the screen. Either one is a common and acceptable practice and comes down to a matter of taste.