Flutter Blue Read Values from 2 Characteristics with notify - flutter

Question

I'm a beginner in flutter and want to program a app with Bluetooth LE. I use flutter_blue. My App works if i only want to read the value of one characteristic. Now i need to read a second characteristic and that is the problem. I'm using a example from the esp32 dust sensor. The main is similar to the flutter blue example. The step to the next site is work with the following code:
StreamBuilder<List<ScanResult>>(
stream: FlutterBlue.instance.scanResults,
initialData: [],
builder: (c, snapshot) => Column(
children: snapshot.data
.map(
(r) => ScanResultTile(
result: r,
onTap: () => Navigator.of(context)
.push(MaterialPageRoute(builder: (context) {
r.device.connect();
return SensorPage(device: r.device);
})),
),
That works ok. At the Sensor-Page there is the code for the Page which starts with:
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onWillPop,
child: Scaffold(
appBar: AppBar(
title: Text(' Connect'),
),
body: Container(
// color: Colors.purple,
decoration: BoxDecoration(
image: DecorationImage(
// image: AssetImage("lib/Images/knaus.jpg"),
image: AssetImage("lib/Images/innen.jpg"),
fit: BoxFit.cover,
),
),
child: !isReady
? Center(
child: Text(
"Warte auf Verbindung...",
style: TextStyle(fontSize: 24, color: Colors.red),
),
)
: Container(
child: StreamBuilder<List<int>>(
stream: wt_Ist_stream,
builder: (BuildContext context,
AsyncSnapshot<List<int>> snapshot) {
if (snapshot.hasError)
return Text('Error: ${snapshot.error}');
if (snapshot.connectionState ==
ConnectionState.active) {
_DataParser(snapshot.data);
The characteristics i generate with:
List<BluetoothService> services = await widget.device.discoverServices();
services.forEach((service) {
if (service.uuid.toString() == SERVICE_UUID) {
service.characteristics.forEach((characteristic) {
if (characteristic.uuid.toString() == CHARACTERISTIC_UUID_WT_RcvWater) {
characteristic.setNotifyValue(!characteristic.isNotifying);
characteristic1=characteristic;
// characteristic1.setNotifyValue(!characteristic.isNotifying);
wt_Ist_stream = characteristic1.value;
// wt_Soll_stream = service.characteristic.value;
setState(() {
isReady = true;
});
}
if (characteristic.uuid.toString() == CHARACTERISTIC_UUID_WT_Soll) {
characteristic.setNotifyValue(!characteristic.isNotifying);
characteristic2=characteristic;
// characteristic2.setNotifyValue(!characteristic2.isNotifying);
wt_Soll_stream = characteristic2.value;
// characteristic2.value.listen((InputString2)
// wt_Soll_stream = service.characteristic.value;
}
//Updating characteristic to perform write operation.
if (characteristic.uuid.toString() == CHARACTERISTIC_UUID_WT_TxWater) {
characteristic_Write=characteristic;
}
});
}
});
if (!isReady) {
_Pop();
}
}
Both reading-Characteristics are send Data to the app and i get the notification, that new data available [onCharacteristicChanged] uuid: 456e869c-d393-4cec-9f43-cef5382eab72].
but my Dataparser will only start if the value for uuid ...b72(wt_Ist_stream) changed. Then he gets the right string from snapshot.data.
If i changed the Streambuilder-Stream
child: StreamBuilder<List<int>>(
stream: wt_Ist_stream,
to
child: StreamBuilder<List<int>>(
stream: wt_Soll_stream,
my dataparser gets the value from characteristic 2. But how can i change my app that my parser starts automatic if one stream (wt_Ist_Stream or wt_Soll_stream) changed and then gets the right value.
The Streambuilder sends the right data to the dataparser but only the stream, which is called in stream:
How can i changed the code, that my parser starts on a stream-change and gets the right values from snapshot.data?
The dataparser-code:
_DataParser(List<int> dataFromDevice) {
String InputString = utf8.decode(dataFromDevice);
if (InputString.length>6) {.....}