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New Contributor
Posts: 5
Registered: ‎06-23-2011
My Device: Any blackberry device
My Carrier: any carrier
Accepted Solution

Midlet not responsive after sending the application in background and resuming it



I have a midlet 2.0 application (no proprietary RIM api, just plain, compliant, midlet 2.0).


On blackberries (tried with two device, one 5.0 and one 6.0) If I switch from the application to the home screen and than back to the application the application is not responsive.


I use the "pointer of the device" to navigate to selectable elements or can click with touch.

The application is written with the gaming api.


After resume up/down/left/right or touch event are not triggered anymore.

If an element was left selected I can click and the application enter that element returning to work.


On Nokia devices this do not happen indicating there is something different happening in the blackberry.


I extended javax.microedition.lcdui.Canvas to handle keywords / touch events, draw on the screen through javax.microedition.lcdui.Graphics


I have two CustomCanvas in an array and switch between them to change page (so that I can load the new page in background before switching).


Every time a new request is issued, from my midlet class, extending javax.microedition.midlet.MIDlet, I do:


Display display = Display.getDisplay(this);

// do stuff here



At initialization ( startApp() method from javax.microedition.midlet.MIDlet ) if it's the first time I create some instance of custom classing initializing them. 


I never again initialize them and do nothing on resumeApp() nor on startApp() if called after a resume.


Question are:

which kind of event can I get for background / foreground event on a midlet running on a blackberry?

and what should I re-initialize / check to handle these events?












New Contributor
Posts: 5
Registered: ‎06-23-2011
My Device: Any blackberry device
My Carrier: any carrier

Re: Midlet not responsive after sending the application in background and resuming it

The problem was not related to blackberry... a little nasty bug happening only on blackberry for reason I can't explain...

If anything like this happen check where do you instantiate your Canvases and where do you keep them in memory...
should be consistent with startApp / stopApp...

If you don't remove the Canvas on stop then do not re-instantiate it in startApp if it's a resume.