Question

I’m trying to get a Samsung Galaxy Ace with Android to communicate with a Nokia N95 via Bluetooth.
I have written an application for the J2ME side that communicates just fine using 2 symbian devices.
I’ve also created a version for Android that communicates very well between Android devices.
Initiating a connection from J2ME to Android works as well.
Creating a connection from Android to J2ME gives me the problems.

Focusing on the problem: The first connection attempt fails using createRfcommSocketToServiceRecord. I then try the workaround using reflection and the createRfcommSocket method to channel 1, then 2, then 3, then 4, if they fail respectively. At one point I will have a connection and I can send data but when I try to receive using InputStream.read() it just hangs so I think the connection in J2ME is somehow not piped to my application.

So I created test applications to see what is wrong on the small scale. The N95 sets up a listener with a UUID encrypted and authenticated and the Android application creates a connection with createRfcommSocketToServiceRecord. This works!
I can also run the real Android application and send messages to the test application of the N95. From this experience I have drawn the conclusion that the fault must lie in the J2ME version.

I am wondering if anyone has tips on how to go about debugging this.
I am currently commenting out code, building, sending the app to the phone, installing, testing, repeating.
This is very weary and is going very slow but I have no other option for testing this.
I would also appreciate insight on why createRfcommSocket connection doesn’t reply. Do I have to register something on the J2ME side?
Thanks for your time.

Answer 1

I have resolved this particular issue by reviewing my code in detail and have found that I had incorrectly implemented my custom output streams.

out.write(x);
out.write(y);
out.flush();

the stream is not automatically flushed in j2me