Android Question How to read serial data from another device

Hi...
Execuse me, plase help me, i have a project, to connect and communicate between Android device and Arduino, but i have a problem, when i try to read a serial data, the communications always broken suddenly, so here i my question :

1. How to read serial data from arduino by using bluetooth or FTDI ?

Please help me...

Thank you so much

Regards

Agus