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Editorial Team
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Asked: 2026-06-01T13:58:02+00:00

I send the text file to multiple devices using the following code, ContentValues values

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I send the text file to multiple devices using the following code,

ContentValues values = new ContentValues(); 
String filePath1   =Environment.getExternalStorageDirectory().toString()+"/filename.txt";
values.put(BluetoothShare.URI, Uri.fromFile(newFile(filePath1)).toString()); 
values.put(BluetoothShare.DESTINATION,itDevices.getAddress());               values.put(BluetoothShare.DIRECTION, BluetoothShare.DIRECTION_OUTBOUND); 
Long ts = System.currentTimeMillis(); 
values.put(BluetoothShare.TIMESTAMP, ts); 
Uri contentUri = getContentResolver().insert(BluetoothShare.CONTENT_URI, values);

I want the same type of code for sending a message. By using the Bluetooth API application when i try to send the message to multiple devices first i connect to a device and send message to that device and again disconnect and connect to another device and send message to another device in this way this goes.

Is it possible to send a message to multiple devices one by one without disconnect the communication ?

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1 Answer

  1. Editorial Team

    Yes, I believe it is possible to exchange messages with multiple Android Bluetoooth devices simultaneously – without disconnecting and reconnecting.

    Leaving the Android API aside for starters, Bluetooth definitely allows you to connect to and communicate with multiple devices simultaneously. All Bluetooth connections happen in piconets which include a master and up to 7 slaves. A device can be part of more then one piconet but this is inefficient (the timing of the two piconets isn’t coordinated) and can be unreliable, so if you want to connect to multiple other devices you must make sure you are the master.

    I’ve done this sort of thing with BlueZ (the Bluetooth stack on most Linux and Android devices including AOSP) so I can verify that it is fairly straight-forward and works reliably.

    However, I’ve only done one-to-one connections on Android, so I can’t say for sure how you control the master-slave assignment there. Android provides much less power and control compared to regular Linux, and it provides no way to directly read or change the master slave role assignment.

    In theory, you should be able to control the roles based on the rule that which-ever side initiates the connection will be the master, but I would want to do some testing to see what else might be going on. My concern comes mainly from the possibility that one of the client devices (that you expect to be a slave) might already have a connection to e.g. a headset or keyboard, so when it receives the incoming connection request it might request to switch to master role so it can add your server to its piconet.

    What I would suggest is, when you are testing, get access to hcitool on one of your devices (e.g. a Linux box or a rooted Android) and do ‘hcitool con’ and it will give you a list of the current connections and I think this includes the role. (hcitool is a standard tool on Linux and is included in AOSP.) I guess you could also just use the empirical approach: if you are able to create a bunch of simultaneous connections that work reliably then it doesn’t matter much how it works – just make sure you test situations where some of the devices have existing connections to other devices.

    Sorry about going on, but I think this is a good question and would be interested to hear from people who have done this on Android. I think I’ve heard of multi-player Bluetooth games for Android – I wonder if those work reliably.

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