Motorola J2ME Specifications download pdf (Page 29)

Application Management

MIDlet Control of MIDlet State Transitions

MIDlets have a lot of flexibility to control their own state. A MIDlet can call its own

startApp(), pauseApp(), and destroyApp() methods, however those

are the methods that the AMS uses to indicate a state transition to the MIDlet. The MIDlet

can call those methods if it wishes to perform the work that it would typically do during that

state transition.

Other sets of methods the MIDlet can use to cause state transitions are

resumeRequest(), notifyPaused(), and notifyDestroyed().

Since the system user interface has priority, a MIDlet cannot force itself into the active

state, but it can request that it be resumed via a resumeRequest(). If the system

is not busy, it will automatically grant the request. However, if the device is not in the idle

screen, then it displays an alert dialog to the user to resume or end the MIDlet. If the user

denies the request, the MIDlet is not notified, however if the user grants the request, the

MIDlet’s startApp() method is called, and it gains focus when that finishes.

The MIDlet has more control when it decides it wants to be paused or destroyed. The

MIDlet performs the necessary work by calling its own pauseApp() or

destroyApp() method, then notifies the AMS of its intentions by calling

notifyPaused() and notifyDestroyed() appropriately. Once notified, the

AMS transition the MIDlet’s state and revoke focus.

Java System

The Java Settings Menu allows management of MIDlet suites, as well as system

maintainance. The Java System feature gives statistics about the system such as:

• CLDC Version

• MIDP Version

• Data Space and Program Space (Free space)

• Total Heap Size

• The figure below depicts the Java System Menu.

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Motorola J2ME Specifications Page 29