“Null”不能分配給“Position”型別的變數

我想使用“geolocator”包從用戶那里獲取地理位置資料。邏輯是這樣的，當我收到一個地理位置時，我將它發送到谷歌地圖的控制器，一段時間后地圖根據接收到的坐標傳輸。我寫了一個函式，但它拋出了一個錯誤：

“Null”型別的值不能分配給“Position”型別的變數。嘗試更改變數的型別，或將右側型別轉換為“位置”。

那里顯示的錯誤

Future<void> _getCurrentPosition() async {
Position position = await Geolocator.getCurrentPosition(
        desiredAccuracy: LocationAccuracy.best, forceAndroidLocationManager: true)
    .then((Position position) async {
  final GoogleMapController controller = await _controller.future;
  controller.animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
      target: LatLng(position.latitude, position.longitude), zoom: 14)));
}).catchError((e) {
  print(e);
});}

在此替換部分功能后

Position? position = await Geolocator.getCurrentPosition(
        desiredAccuracy: LocationAccuracy.best, forceAndroidLocationManager: true)
    .then((Position position) async {
  final GoogleMapController controller = await _controller.future;
  controller.animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
      target: LatLng(position.latitude, position.longitude), zoom: 14)));
}).catchError((e) {
  print(e);
});}

還有一件事，當我在物理設備上運行應用程式時，除錯器會顯示以下訊息：Restarted application in 1 796ms. 2022-05-01 23:39:05.165 Runner[2516/0x102610580] [lvl=3] [GMSx_CCTClearcutUploader crashIfNecessary] Multiple instances of CCTClearcutUploader were instantiated. Multiple uploaders function correctly but have an adverse affect on battery performance due to lock contention. [tcp] tcp_input [C4.1:3] flags=[R] seq=611763406, ack=0, win=0 state=ESTABLISHED rcv_nxt=611763406, snd_una=1878468883 Connection 4: received failure notification Connection 4: received ECONNRESET with incomplete TLS handshake - generating errSSLClosedNoNotify Connection 4: failed to connect 3:-9816, reason -1 Connection 4: encountered error(3:-9816) Task <D01E9B91-BB3F-4674-AB74-5063E6362617>.<1> HTTP load failed, 0/0 bytes (error code: -1200 [3:-9816]) 2 [tcp] tcp_input [C4.1:3] flags=[R] seq=611763406, ack=0, win=0 state=CLOSED rcv_nxt=611763406, snd_una=1878468883 Task <D01E9B91-BB3F-4674-AB74-5063E6362617>.<1> finished with error [-1200] Error Domain=NSURLErrorDomain Code=-1200 "An SSL error has occurred and a secure connection to the server cannot be made." UserInfo={NSErrorFailingURLStringKey=https://clients4.google.com/glm/mmap, NSLocalizedRecoverySuggestion=Would you like to connect to the server anyway?, _kCFStreamErrorDomainKey=3, _NSURLErrorFailingURLSessionTaskErrorKey=LocalUploadTask <D01E9B91-BB3F-4674-AB74-5063E6362617>.<1>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalUploadTask <D01E9B91-BB3F-4674-AB74-5063E6362617>.<1>" ), NSLocalizedDescription=An SSL error has occurred and a secure connection to the server cannot be made., NSErrorFailingURLKey=https://clients4.google.com/glm/mmap, NSUnderlyingError=0x28150ca50 {Error Domain=kCFErrorDomainCFNetwork Code=-1200 "(null)" UserInfo={_kCFStreamPropertySSLClientCertificateState=0, _kCFNetworkCFStreamSSLErrorOriginalValue=-9816, _kCFStreamErrorDomainKey=3, _kCFStreamErrorCodeKey=-9816, _NSURLErrorNWPathKey=satisfied (Path is satisfied), viable, interface: utun2, ipv4, dns, expensive}}, _kCFStreamErrorCodeKey=-9816} [tcp] tcp_input [C4.1:3] flags=[R] seq=611763406, ack=0, win=0 state=CLOSED rcv_nxt=611763406, snd_una=1878468883 -canOpenURL: failed for URL: "comgooglemaps://" - error: "This app is not allowed to query for scheme comgooglemaps" -canOpenURL: failed for URL: "googlechromes://" - error: "This app is not allowed to query for scheme googlechromes" Lost connection to device.

它是什么，這很重要嗎？非常感謝！

uj5u.com熱心網友回復：

將您的代碼替換為

try{
    Position position = await Geolocator.getCurrentPosition(
            desiredAccuracy: LocationAccuracy.best, forceAndroidLocationManager: true)
        ..then((Position position) async {
      final GoogleMapController controller = await _controller.future;
      controller.animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
          target: LatLng(position.latitude, position.longitude), zoom: 14)));
    }).catchError((e) {
      print(e);
    });}
}catch(e){}

或者

Position? position = await Geolocator.getCurrentPosition(
            desiredAccuracy: LocationAccuracy.best, forceAndroidLocationManager: true)
        .then((Position position) async {
      final GoogleMapController controller = await _controller.future;
      controller.animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
          target: LatLng(position.latitude, position.longitude), zoom: 14)));
    }).catchError((e) {
      print(e);
    });}

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