Android code for receiving data from USB device by my Android cellular phone

Question

Is connection.BulkTransfer used for transfering data in both ways? I mean:

1. To endpoint_OUT
2. From endpoint_IN?

But if I want to receive data from endpoint_IN, how do I know how much data is waiting for me at endpoint_IN? How does the code look like for such a data transfer?

I want to receive data from a USB device to my Android cellular phone. I expected to find a method that samples the number of bytes which are waiting on endpoint_IN.