Generate heat on an android phone (from code, of course) -

I need an Android phone heat (do not ask ...)

So far I have a Tried to run the maximum priority thread, while ROL is an integer with a loop, but it generates very little heat, even if the phone is almost closed. I tried to do complex math in the loop, but the results were similar. I tried with more threads, but just as it was expected, it was with just one thread.

Edit : This is basically an application that should run as a background service (Android service started with startService) which to use the information Indicates that he is walking (or not). Ideally, there should not be any UI in it, except for control-activity, it has already started service, notifications and control activity. This service uses its thread for the heating of the phone so that it will not interfere with the activity UI (which is in the same Android app), now I just need to type the "flesh" of the thread, i.e. some code Which actually happens to warm up the phone.

Actually CPU:

• Keep the screen bright (if You have an OLED full of white color). The best way to do this is with an activity setting FLAG_KEEP_SCREEN_ON and maximum brightness.
• Monitor the location with GPS.
• Send and receive data over the network.
• Play audio.

Something that you can not do in the software, some easy graphics (to run the GPU) but also a large battery drain is in the lower signal area, hence the cell radio Its power must be suppressed.

Or just run Google navigation ... it already does almost all, and actually bigger battery drainer and device is hot;)