notification if the Bluetooth is turned off in android app

Question

Im currently working on a android application. I have to notify the user whenever the bluetooth of the device is turned off while the application is currently running.

How to notify the remote device that BT is turned off?

Answer 1

Register BroadcastReceiver with intent action BluetoothAdapter.ACTION_STATE_CHANGED and move your notifiyng code into onReceive method. Don't forget to check if new state is OFF

if(BluetoothAdapter.ACTION_STATE_CHANGED.equals(intent.getAction())) {
    if(intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1) 
        == BluetoothAdapter.STATE_OFF)
        // Bluetooth was disconnected
}

Answer 2

If you want to detect when the user is DISCONNECTING his Bluetooth, and later, detect when the user has his Bluetooth DISCONNECTED, you should do the following steps:

1) Get the user BluetoothAdapter:

BluetoothAdapter btAdapter = BluetoothAdapter.getDefaultAdapter();    

2) Create and configure your Receiver, with a code as this:

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {

        String action = intent.getAction();

        // It means the user has changed his bluetooth state.
        if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) {

            if (btAdapter.getState() == BluetoothAdapter.STATE_TURNING_OFF) {
                // The user bluetooth is turning off yet, but it is not disabled yet.
                return;
            }

            if (btAdapter.getState() == BluetoothAdapter.STATE_OFF) {
                // The user bluetooth is already disabled.
                return;
            }

        }
    }
};    

3) Register your BroadcastReceiver into your Activity:

this.registerReceiver(mReceiver, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));