BluetoothAdapter.getDefaultAdapter().getProfileProxy(this, mScanCallback, BluetoothProfile.A2DP);

    BluetoothProfile.ServiceListener mScanCallback = new BluetoothProfile.ServiceListener() {
    @Override
    public void onServiceConnected(int profile, BluetoothProfile proxy) {
        if (profile == BluetoothProfile.A2DP) {
            proxy.getConnectedDevices().forEach(device -> {
                if (selectedDevice1 != null
                        && selectedDevice1.getDeviceMAC().equalsIgnoreCase(device.getAddress())) {
                    try {
                        Class clazz = Class.forName("android.bluetooth.BluetoothA2dp");
                        Method method = clazz.getMethod("setActiveDevice", BluetoothDevice.class);
                        method.invoke(proxy, device);
                    } catch (Exception e) {
                        Log.e("TEST", "", e);
                    }
                }
            });
        }
    }

    @Override
    public void onServiceDisconnected(int i) {
    }
};