J2ME in a Nutshell

Name

Display

Synopsis

This class represents a MIDlet’s view of the screen of the device on which it is running. Every MIDlet has access to a single instance of this class, which it may obtain a reference to by calling the static getDisplay() method once its startApp() method has been entered for the first time. Subsequent calls will return the same instance, which remains valid until the MIDlet’s destroyApp() method completes, or until the MIDlet calls notifyDestroyed(). When a MIDlet is in the foreground, the Display object becomes associated with the screen; when the MIDlet is not in the foreground, operations performed on the Display have no effect until the MIDlet gains the foreground.

A Display object shows the content of the Displayable passed to its setCurrent() method. MIDlets usually use the single-argument variant of this method to switch from one screen to another. When displaying an Alert, if the single-argument variant is used, the Displayable that was originally displayed will be restored when the Alert is dismissed. If it is appropriate to display a different screen when the Alert is dismissed, the two-argument variant may be used and the new Displayable supplied as its second argument.

The getCurrent() method returns a reference to the Displayable that the Display object is currently showing to the user if it is in the foreground, or would show to the user if it is in the background. It is important to note when using getCurrent() that the setCurrent() method does ...