Motorola C450 User Manual

5 
Application Management  
 

29 

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.