J2ME in a Nutshell

Name

MIDlet

Synopsis

This class is the abstract base class from which all MIDlet classes are derived. MIDlets run on devices that support the Mobile Information Device Profile (MIDP), under the control of device-dependent application management software (AMS) that creates, schedules, and destroys them.

MIDlets are grouped together into suites. MIDlet suites are always installed, managed, and removed as a single unit. All MIDlets from the same suite execute within a single Java virtual machine instance, enabling them to share data using static variables declared in their class implementations. MIDlets can also share information by using RecordStores, which can be accessed using the APIs defined in the javax.microedition.rms package. Partitioning MIDlets so that only those from the same suite execute in the same VM ensures that potentially malicious MIDlets from one suite cannot read or modify information belonging to another. RecordStores are similarly protected by ensuring that they are private to the MIDlet suite whose MIDlets create them.

Of all the MIDlets that are currently executing on a device, only one of them is considered to be in the foreground. The foreground MIDlet is unique in that it has access to the device’s screen, keypad, and pointer (if the device supports them). Updates to the screen made by the foreground MIDlet will be seen by the user--possibly after a short delay-- whereas those made in a MIDlet that is in the background will not affect the display until ...