The main structure for a BlackBerry® device user interface is the Screen object. A BlackBerry Java® Application may display more than one screen at a time, but only one screen in a BlackBerry Java Application is active at one time.

The user interface APIs initialize simple Screen objects. Once you create a screen, you can add fields and a menu to the screen and display it to the BlackBerry device user by pushing it on to the UI stack. The menu object has associated menu items that are runnable objects, which perform a specific task when the BlackBerry device user selects one of the items. For example, menu items may invoke the necessary code to establish a network connection, commit a data object to memory or close the BlackBerry Java Application. For a more sophisticated custom BlackBerry Java Application, you can customize the BlackBerry device user interface and implement new field types, as required. You can also add custom navigation and trackwheel behavior.

The Screen class does not implement disambiguation, which is required for complex input methods, such as international keyboards. For seamless integration of the different input methods, extend Field or one of its subclasses. Do not use Screen objects for typing text.

For knowledge base articles about displaying and working with screens, visit the BlackBerry Developer Zone at www.blackberry.com/developers .

• Screen classes
  
• Create a screen
  
• How the BlackBerry JVM manages screens
  
• Provide screen navigation when using a MainScreen
  
• Manage a drawing area