With the Nexus7 , 1st generation tablet i often come across missing driver problems and it was not getting recognised by jDeveloper and thus debugging MAF Applications would be not possible.
ERROR:
When i deploy to device from the jdeveloper i was getting an error in the console saying that, no devices are recognised ,please restart abd server.
Here just restarting the abd server might not help since the driver was missing.
FIX:
Download the driver from here:
http://developer.android.com/sdk/win-usb.html#download
and go to device manager , find the device NEXUS7 ,right click and go to its properties, hit the update Driver Button . Browse the folder location where the driver was downloaded.
It may not work if tried to deploy soon after the update, So restart the system and retry and it works for me.
Thanks, Happy Debugging !!!