Archived:Infrequent paint() call when Bluetooth is used in S60 devices (Known Issue)
The Java Bluetooth API behaves differently in S60 and Series 40.
I have a Java ME application that paints an animation while another thread reads from a Bluetooth connection (about 30 bytes every 20 ms). This application works perfectly on Series 40 phones. On S60 phones, however, the animation becomes nearly frozen while the connection is being read. It appears that Java threads are running frequently enough (reading Bluetooth / calling repaint) but that the system (GUI Event thread) is infrequently calling paint().
In S60 Java is not calling paint while Bluetooth data is received whereas in Series 40 Java is calling paint while Bluetooth data is received.
However, the Nokia N93 is the first S60 device where the MIDlet behaves correctly, that is, simultaneous painting is being done when Bluetooth data is received.
How to reproduce
If you have a client-server application, you can test whether the MIDlet behaves correctly.
- Install the application on two Nokia S60 devices
- Make sure Bluetooth is turned on.
- Start the application on server.
- Start the application on client.
- During the initialization of the Bluetooth connection, the application/screen freezes. When the connection has been established, the paint() method is called but not frequently enough.
No solution exists.