When you are developing an Android platform application you use a device (actual or virtual) to see how it looks and test it. The run process checks your machine for connected devices on every run and automatically decides which one to use.
The check sequence is as follows:
- Physical device connected
In order to detect the device connected, the adecquate device driver must be installed. Otherwhise, the device will be ignored by the check sequence and the next sequence step will be executed.
Besides having all functions (GPS, etc.) physical devices provide the fastest prototyping environment.
If an emulator is already started, it is selected to run the application.
If you want to run your application using your own AVD you must start the emulator with it _before_ running.
If none of the above could be used, a new emulator is executed with the default AVD.