FusedLocation GoogleApi - 侦听器不得为空 (Xamarin.Android)
Posted
技术标签:
【中文标题】FusedLocation GoogleApi - 侦听器不得为空 (Xamarin.Android)【英文标题】：FusedLocation GoogleApi - Listener must not be null (Xamarin.Android) 【发布时间】：2016-12-19 09:28:56 【问题描述】：我得到以下信息：
Java.Lang.NullPointerException：监听器不能为空。
似乎无法摆脱它。我已经用尽了所有可能的解决方案。
using System;
using android.App;
using Android.Gms.Location;
using Android.Gms.Common.Apis;
using Android.OS;
using Android.Gms.Maps.Model;
using Android.Widget;
using Android.Locations;
using Android.Gms.Common;
namespace Maps.Droid.LocationService
public class FusedLocation : GoogleApiClient.IConnectionCallbacks, GoogleApiClient.IOnConnectionFailedListener, Android.Gms.Location.ILocationListener
private Activity activity;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
private Location currentLocation;
private bool locationAvailable = false;
public FusedLocation(Activity activity)
this.activity = activity;
setGoogleApiClient();
setLocationRequest();
//var requestBuilder = new LocationSettingsRequest.Builder().AddLocationRequest(mLocationRequest);
//requestBuilder.SetAlwaysShow(true);
// Next check whether the current location settings are satisfied:
//var result = LocationServices.SettingsApi.CheckLocationSettings(mGoogleApiClient, requestBuilder.Build());
private void setGoogleApiClient()
if (mGoogleApiClient == null)
mGoogleApiClient = new GoogleApiClient.Builder(activity)
.AddConnectionCallbacks(this)
.AddOnConnectionFailedListener(this)
.AddApi(LocationServices.API)
.Build();
private void setLocationRequest()
if (mLocationRequest == null)
mLocationRequest = new LocationRequest();
mLocationRequest.SetInterval(LocationTracker.MIN_TIME_BW_UPDATES);
mLocationRequest.SetFastestInterval(LocationTracker.MIN_TIME_BW_UPDATES / 2);
mLocationRequest.SetPriority(LocationRequest.PriorityHighAccuracy);
public LatLng getLatLng()
return new LatLng(currentLocation.Latitude, currentLocation.Longitude);
public double getLatitude()
return currentLocation == null ? 0.0 : currentLocation.Latitude;
public double getLongitude()
return currentLocation == null ? 0.0 : currentLocation.Longitude;
public void startLocationServices()
if (!mGoogleApiClient.IsConnected)
mGoogleApiClient.Connect();
LocationServices.FusedLocationApi.RequestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
public void pauseLocationServices()
// Stop location updates to save battery, but don't disconnect the GoogleApiClient object.
if (mGoogleApiClient.IsConnected)
LocationServices.FusedLocationApi.RemoveLocationUpdates(mGoogleApiClient, this);
public void stopLocationServices()
// only stop if it's connected, otherwise we crash
if (mGoogleApiClient != null)
mGoogleApiClient.Disconnect();
public bool canGetLocation()
return locationAvailable;
public void OnConnected(Bundle connectionHint)
// Get last known recent location. If the user launches the activity,
// moves to a new location, and then changes the device orientation, the original location
// is displayed as the activity is re-created.
if (currentLocation == null)
currentLocation = LocationServices.FusedLocationApi.GetLastLocation(mGoogleApiClient);
locationAvailable = true;
// Begin polling for new location updates.
startLocationUpdates();
// Trigger new location updates at interval
protected void startLocationUpdates()
setGoogleApiClient(); // The method checks if it has been already initialized
setLocationRequest(); // The method checks if it has been already initialized
// Request location updates
LocationServices.FusedLocationApi.RequestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
public void OnConnectionSuspended(int cause)
// GoogleApiClient will automatically attempt to restore the connection.
// Applications should disable UI components that require the service, and wait for a call to onConnected(Bundle) to re-enable them
if (cause == GoogleApiClient.ConnectionCallbacks.CauseServiceDisconnected)
Toast.MakeText(activity, "Location Services disconnected. Please re-connect.", ToastLength.Long).Show();
else if (cause == GoogleApiClient.ConnectionCallbacks.CauseNetworkLost)
Toast.MakeText(activity, "Network lost. Please re-connect.", ToastLength.Long).Show();
public void OnLocationChanged(Location location)
currentLocation = location;
public void OnConnectionFailed(ConnectionResult result)
if (mGoogleApiClient != null)
mGoogleApiClient.Connect();
public IntPtr Handle
get;
public void Dispose()
看来问题出在方法setGoogleApiClient();
检查这张图片：
发现错误后点击继续：
08-12 16:09:14.446 D/OpenGLRenderer(13084): Enabling debug mode 0
08-12 16:09:15.176 D/Mono (13084): Assembly Ref addref Maps.Droid[0x64b8c7f8] -> Xamarin.GooglePlayServices.Maps[0x64bdfe50]: 2
08-12 16:09:15.176 D/Mono (13084): Assembly Ref addref Maps.Droid[0x64b8c7f8] -> Xamarin.GooglePlayServices.Basement[0x64bde280]: 2
08-12 16:09:15.176 D/Mono (13084): Assembly Ref addref Maps.Droid[0x64b8c7f8] -> Xamarin.GooglePlayServices.Location[0x64bdf070]: 2
08-12 16:09:15.206 D/Mono (13084): Assembly Ref addref Xamarin.GooglePlayServices.Location[0x64bdf070] -> Xamarin.GooglePlayServices.Basement[0x64bde280]: 3
08-12 16:09:15.206 D/Mono (13084): Assembly Ref addref Maps.Droid[0x64b8c7f8] -> Xamarin.GooglePlayServices.Base[0x64bdd490]: 2
08-12 16:09:15.206 D/Mono (13084): Assembly Ref addref Xamarin.GooglePlayServices.Base[0x64bdd490] -> Xamarin.GooglePlayServices.Basement[0x64bde280]: 4
08-12 16:09:15.216 I/dalvikvm(13084): Could not find method android.content.pm.PackageManager.getPackageInstaller, referenced from method com.google.android.gms.common.zze.zzi
08-12 16:09:15.216 W/dalvikvm(13084): VFY: unable to resolve virtual method 404: Landroid/content/pm/PackageManager;.getPackageInstaller ()Landroid/content/pm/PackageInstaller;
08-12 16:09:15.216 D/dalvikvm(13084): VFY: replacing opcode 0x6e at 0x000b
08-12 16:09:15.216 D/Mono (13084): DllImport searching in: '__Internal' ('(null)').
08-12 16:09:15.216 D/Mono (13084): Searching for 'java_interop_jnienv_call_static_object_method'.
08-12 16:09:15.216 D/Mono (13084): Probing 'java_interop_jnienv_call_static_object_method'.
08-12 16:09:15.216 D/Mono (13084): Found as 'java_interop_jnienv_call_static_object_method'.
08-12 16:09:15.226 D/Mono (13084): DllImport searching in: '__Internal' ('(null)').
08-12 16:09:15.226 D/Mono (13084): Searching for 'java_interop_jnienv_call_int_method_a'.
08-12 16:09:15.226 D/Mono (13084): Probing 'java_interop_jnienv_call_int_method_a'.
08-12 16:09:15.226 D/Mono (13084): Found as 'java_interop_jnienv_call_int_method_a'.
08-12 16:09:15.336 D/Mono (13084): DllImport attempting to load: '/system/lib/liblog.so'.
08-12 16:09:15.336 D/Mono (13084): DllImport loaded library '/system/lib/liblog.so'.
08-12 16:09:15.336 D/Mono (13084): DllImport searching in: '/system/lib/liblog.so' ('/system/lib/liblog.so').
08-12 16:09:15.336 D/Mono (13084): Searching for '__android_log_print'.
08-12 16:09:15.336 D/Mono (13084): Probing '__android_log_print'.
08-12 16:09:15.336 D/Mono (13084): Found as '__android_log_print'.
08-12 16:09:15.336 I/mono-stdout(13084): 1
1
1
08-12 16:09:15.346 I/mono-stdout(13084): 1
2
2
08-12 16:09:15.346 I/mono-stdout(13084): 2
08-12 16:09:15.346 I/mono-stdout(13084): 2
08-12 16:09:15.346 D/Mono (13084): DllImport searching in: '__Internal' ('(null)').
08-12 16:09:15.346 D/Mono (13084): Searching for 'java_interop_jnienv_get_static_field_id'.
08-12 16:09:15.346 D/Mono (13084): Probing 'java_interop_jnienv_get_static_field_id'.
08-12 16:09:15.346 D/Mono (13084): Found as 'java_interop_jnienv_get_static_field_id'.
08-12 16:09:15.356 D/Mono (13084): DllImport searching in: '__Internal' ('(null)').
08-12 16:09:15.356 D/Mono (13084): Searching for 'java_interop_jnienv_get_static_object_field'.
08-12 16:09:15.356 D/Mono (13084): Probing 'java_interop_jnienv_get_static_object_field'.
08-12 16:09:15.356 D/Mono (13084): Found as 'java_interop_jnienv_get_static_object_field'.
Unhandled Exception:
Java.Lang.NullPointerException: Listener must not be null
08-12 16:09:17.826 D/Mono (13084): DllImport attempting to load: '/system/lib/liblog.so'.
08-12 16:09:17.826 D/Mono (13084): DllImport loaded library '/system/lib/liblog.so'.
08-12 16:09:17.826 D/Mono (13084): DllImport searching in: '/system/lib/liblog.so' ('/system/lib/liblog.so').
08-12 16:09:17.826 D/Mono (13084): Searching for '__android_log_print'.
08-12 16:09:17.826 D/Mono (13084): Probing '__android_log_print'.
08-12 16:09:17.836 D/Mono (13084): Found as '__android_log_print'.
08-12 16:09:17.856 I/MonoDroid(13084): UNHANDLED EXCEPTION:
08-12 16:09:17.866 I/MonoDroid(13084): Java.Lang.NullPointerException: Listener must not be null
08-12 16:09:17.866 I/MonoDroid(13084): at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/3540/1cf254db/source/mono/external/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143
08-12 16:09:17.876 I/MonoDroid(13084): at Java.Interop.JniEnvironment+InstanceMethods.CallObjectMethod (JniObjectReference instance, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x00085] in /Users/builder/data/lanes/3540/1cf254db/source/Java.Interop/src/Java.Interop/Java.Interop/JniEnvironment.g.cs:11283
08-12 16:09:17.876 I/MonoDroid(13084): at Android.Runtime.JNIEnv.CallObjectMethod (IntPtr jobject, IntPtr jmethod, Android.Runtime.JValue* parms) [0x00000] in /Users/builder/data/lanes/3540/1cf254db/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:102
08-12 16:09:17.876 I/MonoDroid(13084): at Android.Gms.Common.Apis.GoogleApiClient+Builder.AddConnectionCallbacks (IConnectionCallbacks listener) [0x0004a] in <filename unknown>:0
08-12 16:09:17.876 I/MonoDroid(13084): at Maps.Droid.LocationService.FusedLocation..ctor (Android.App.Activity activity) [0x000a0] in C:\Users\Gustavo.Costa\documents\visual studio 2015\Projects\Maps\Maps\Maps.Droid\LocationService\FusedLocation.cs:38
08-12 16:09:17.876 I/MonoDroid(13084): at Maps.Droid.LocationService.LocationTracker..ctor (Android.App.Activity activity) [0x00026] in C:\Users\Gustavo.Costa\documents\visual studio 2015\Projects\Maps\Maps\Maps.Droid\LocationService\LocationTracker.cs:22
08-12 16:09:17.876 I/MonoDroid(13084): at Maps.Droid.MapActivity.OnCreate (Android.OS.Bundle savedInstanceState) [0x00015] in C:\Users\Gustavo.Costa\documents\visual studio 2015\Projects\Maps\Maps\Maps.Droid\MapActivity.cs:15
08-12 16:09:17.876 I/MonoDroid(13084): at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (IntPtr jnienv, IntPtr native__this, IntPtr native_savedInstanceState) [0x00011] in /Users/builder/data/lanes/3540/1cf254db/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Android.App.Activity.cs:2426
08-12 16:09:17.876 I/MonoDroid(13084): at (wrapper dynamic-method) System.Object:0a7eba53-2ed2-4ace-97be-6a8e8dacad4a (intptr,intptr,intptr)
08-12 16:09:17.876 I/MonoDroid(13084): --- End of managed Java.Lang.NullPointerException stack trace ---
08-12 16:09:17.876 I/MonoDroid(13084): java.lang.NullPointerException: Listener must not be null
08-12 16:09:17.876 I/MonoDroid(13084): at com.google.android.gms.common.internal.zzx.zzb(Unknown Source)
08-12 16:09:17.876 I/MonoDroid(13084): at com.google.android.gms.common.api.GoogleApiClient$Builder.addConnectionCallbacks(Unknown Source)
08-12 16:09:17.876 I/MonoDroid(13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.n_onCreate(Native Method)
08-12 16:09:17.876 I/MonoDroid(13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.onCreate(MapActivity.java:33)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.Activity.performCreate(Activity.java:5411)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.access$800(ActivityThread.java:139)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 16:09:17.876 I/MonoDroid(13084): at android.os.Handler.dispatchMessage(Handler.java:102)
08-12 16:09:17.876 I/MonoDroid(13084): at android.os.Looper.loop(Looper.java:136)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.main(ActivityThread.java:5230)
08-12 16:09:17.876 I/MonoDroid(13084): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 16:09:17.876 I/MonoDroid(13084): at java.lang.reflect.Method.invoke(Method.java:515)
08-12 16:09:17.876 I/MonoDroid(13084): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:780)
08-12 16:09:17.876 I/MonoDroid(13084): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:596)
08-12 16:09:17.876 I/MonoDroid(13084): at dalvik.system.NativeStart.main(Native Method)
08-12 16:09:17.876 I/MonoDroid(13084): --- End of managed Java.Lang.NullPointerException stack trace ---
08-12 16:09:17.876 I/MonoDroid(13084): java.lang.NullPointerException: Listener must not be null
08-12 16:09:17.876 I/MonoDroid(13084): at com.google.android.gms.common.internal.zzx.zzb(Unknown Source)
08-12 16:09:17.876 I/MonoDroid(13084): at com.google.android.gms.common.api.GoogleApiClient$Builder.addConnectionCallbacks(Unknown Source)
08-12 16:09:17.876 I/MonoDroid(13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.n_onCreate(Native Method)
08-12 16:09:17.876 I/MonoDroid(13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.onCreate(MapActivity.java:33)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.Activity.performCreate(Activity.java:5411)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.access$800(ActivityThread.java:139)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 16:09:17.876 I/MonoDroid(13084): at android.os.Handler.dispatchMessage(Handler.java:102)
08-12 16:09:17.876 I/MonoDroid(13084): at android.os.Looper.loop(Looper.java:136)
08-12 16:09:17.876 I/MonoDroid(13084): at android.app.ActivityThread.main(ActivityThread.java:5230)
08-12 16:09:17.876 I/MonoDroid(13084): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 16:09:17.876 I/MonoDroid(13084): at java.lang.reflect.Method.invoke(Method.java:515)
08-12 16:09:17.876 I/MonoDroid(13084): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:780)
08-12 16:09:17.886 I/MonoDroid(13084): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:596)
08-12 16:09:17.886 I/MonoDroid(13084): at dalvik.system.NativeStart.main(Native Method)
08-12 16:09:17.886 D/Mono (13084): DllImport searching in: '__Internal' ('(null)').
08-12 16:09:17.886 D/Mono (13084): Searching for 'java_interop_jnienv_throw'.
08-12 16:09:17.886 D/Mono (13084): Probing 'java_interop_jnienv_throw'.
08-12 16:09:17.886 D/Mono (13084): Found as 'java_interop_jnienv_throw'.
An unhandled exception occured.
08-12 16:09:19.416 E/mono (13084):
08-12 16:09:19.416 E/mono (13084): Unhandled Exception:
08-12 16:09:19.416 E/mono (13084): Java.Lang.NullPointerException: Listener must not be null
08-12 16:09:19.416 E/mono (13084): at (wrapper dynamic-method) System.Object:0a7eba53-2ed2-4ace-97be-6a8e8dacad4a (intptr,intptr,intptr)
08-12 16:09:19.416 E/mono (13084): at (wrapper native-to-managed) System.Object:0a7eba53-2ed2-4ace-97be-6a8e8dacad4a (intptr,intptr,intptr)
08-12 16:09:19.416 E/mono (13084): --- End of managed Java.Lang.NullPointerException stack trace ---
08-12 16:09:19.416 E/mono (13084): java.lang.NullPointerException: Listener must not be null
08-12 16:09:19.416 E/mono (13084): at com.google.android.gms.common.internal.zzx.zzb(Unknown Source)
08-12 16:09:19.416 E/mono (13084): at com.google.android.gms.common.api.GoogleApiClient$Builder.addConnectionCallbacks(Unknown Source)
08-12 16:09:19.416 E/mono (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.n_onCreate(Native Method)
08-12 16:09:19.416 E/mono (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.onCreate(MapActivity.java:33)
08-12 16:09:19.416 E/mono (13084): at android.app.Activity.performCreate(Activity.java:5411)
08-12 16:09:19.416 E/mono (13084): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.access$800(ActivityThread.java:139)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 16:09:19.416 E/mono (13084): at android.os.Handler.dispatchMessage(Handler.java:102)
08-12 16:09:19.416 E/mono (13084): at android.os.Looper.loop(Looper.java:136)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.main(ActivityThread.java:5230)
08-12 16:09:19.416 E/mono (13084): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 16:09:19.416 E/mono (13084): at java.lang.reflect.Method.invoke(Method.java:515)
08-12 16:09:19.416 E/mono (13084): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:780)
08-12 16:09:19.416 E/mono (13084): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:596)
08-12 16:09:19.416 E/mono (13084): at dalvik.system.NativeStart.main(Native Method)
08-12 16:09:19.416 E/mono (13084):
08-12 16:09:19.416 E/mono (13084): --- End of managed Java.Lang.NullPointerException stack trace ---
08-12 16:09:19.416 E/mono (13084): java.lang.NullPointerException: Listener must not be null
08-12 16:09:19.416 E/mono (13084): at com.google.android.gms.common.internal.zzx.zzb(Unknown Source)
08-12 16:09:19.416 E/mono (13084): at com.google.android.gms.common.api.GoogleApiClient$Builder.addConnectionCallbacks(Unknown Source)
08-12 16:09:19.416 E/mono (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.n_onCreate(Native Method)
08-12 16:09:19.416 E/mono (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.onCreate(MapActivity.java:33)
08-12 16:09:19.416 E/mono (13084): at android.app.Activity.performCreate(Activity.java:5411)
08-12 16:09:19.416 E/mono (13084): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.access$800(ActivityThread.java:139)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 16:09:19.416 E/mono (13084): at android.os.Handler.dispatchMessage(Handler.java:102)
08-12 16:09:19.416 E/mono (13084): at android.os.Looper.loop(Looper.java:136)
08-12 16:09:19.416 E/mono (13084): at android.app.ActivityThread.main(ActivityThread.java:5230)
08-12 16:09:19.416 E/mono (13084): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 16:09:19.416 E/mono (13084): at java.lang.reflect.Method.invoke(Method.java:515)
08-12 16:09:19.416 E/mono (13084): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:780)
08-12 16:09:19.416 E/mono (13084): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:596)
08-12 16:09:19.416 E/mono (13084): at dalvik.system.NativeStart.main(Native Method)
08-12 16:09:19.416 E/mono (13084):
08-12 16:09:19.416 E/mono-rt (13084): [ERROR] FATAL UNHANDLED EXCEPTION: Java.Lang.NullPointerException: Listener must not be null
08-12 16:09:19.416 E/mono-rt (13084): at (wrapper dynamic-method) System.Object:0a7eba53-2ed2-4ace-97be-6a8e8dacad4a (intptr,intptr,intptr)
08-12 16:09:19.416 E/mono-rt (13084): at (wrapper native-to-managed) System.Object:0a7eba53-2ed2-4ace-97be-6a8e8dacad4a (intptr,intptr,intptr)
08-12 16:09:19.416 E/mono-rt (13084): --- End of managed Java.Lang.NullPointerException stack trace ---
08-12 16:09:19.416 E/mono-rt (13084): java.lang.NullPointerException: Listener must not be null
08-12 16:09:19.416 E/mono-rt (13084): at com.google.android.gms.common.internal.zzx.zzb(Unknown Source)
08-12 16:09:19.416 E/mono-rt (13084): at com.google.android.gms.common.api.GoogleApiClient$Builder.addConnectionCallbacks(Unknown Source)
08-12 16:09:19.416 E/mono-rt (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.n_onCreate(Native Method)
08-12 16:09:19.416 E/mono-rt (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.onCreate(MapActivity.java:33)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.Activity.performCreate(Activity.java:5411)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.access$800(ActivityThread.java:139)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 16:09:19.416 E/mono-rt (13084): at android.os.Handler.dispatchMessage(Handler.java:102)
08-12 16:09:19.416 E/mono-rt (13084): at android.os.Looper.loop(Looper.java:136)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.main(ActivityThread.java:5230)
08-12 16:09:19.416 E/mono-rt (13084): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 16:09:19.416 E/mono-rt (13084): at java.lang.reflect.Method.invoke(Method.java:515)
08-12 16:09:19.416 E/mono-rt (13084): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:780)
08-12 16:09:19.416 E/mono-rt (13084): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:596)
08-12 16:09:19.416 E/mono-rt (13084): at dalvik.system.NativeStart.main(Native Method)
08-12 16:09:19.416 E/mono-rt (13084):
08-12 16:09:19.416 E/mono-rt (13084): --- End of managed Java.Lang.NullPointerException stack trace ---
08-12 16:09:19.416 E/mono-rt (13084): java.lang.NullPointerException: Listener must not be null
08-12 16:09:19.416 E/mono-rt (13084): at com.google.android.gms.common.internal.zzx.zzb(Unknown Source)
08-12 16:09:19.416 E/mono-rt (13084): at com.google.android.gms.common.api.GoogleApiClient$Builder.addConnectionCallbacks(Unknown Source)
08-12 16:09:19.416 E/mono-rt (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.n_onCreate(Native Method)
08-12 16:09:19.416 E/mono-rt (13084): at md551afeb14f78091b7dcc7953e9e497c49.MapActivity.onCreate(MapActivity.java:33)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.Activity.performCreate(Activity.java:5411)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.access$800(ActivityThread.java:139)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 16:09:19.416 E/mono-rt (13084): at android.os.Handler.dispatchMessage(Handler.java:102)
08-12 16:09:19.416 E/mono-rt (13084): at android.os.Looper.loop(Looper.java:136)
08-12 16:09:19.416 E/mono-rt (13084): at android.app.ActivityThread.main(ActivityThread.java:5230)
08-12 16:09:19.416 E/mono-rt (13084): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 16:09:19.416 E/mono-rt (13084): at java.lang.reflect.Method.invoke(Method.java:515)
08-12 16:09:19.416 E/mono-rt (13084): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:780)
08-12 16:09:19.416 E/mono-rt (13084): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:596)
08-12 16:09:19.416 E/mono-rt (13084): at dalvik.system.NativeStart.main(Native Method)
08-12 16:09:19.416 E/mono-rt (13084):
In mgmain JNI_OnLoad
【问题讨论】：
请提供有关错误的更多详细信息，堆栈跟踪也会很有用 Xamarin 没有显示太多，不太确定该怎么做，我正在 Visual Studio 中处理它 它没有连接到google api客户端 在Output 窗格内应该有整个堆栈跟踪。确保您完全点击Continue 以查看相应的跟踪。
@JonDouglas 做到了！
【参考方案1】：
找到问题。您只能在 Activity 上实现 GoogleApiClient。想要创建一个使用位置服务的界面。这种方式不可能！
更新：
我设法找到了解决方案。如果用户有 google play 服务，则使用 FusedLocation 服务，如果用户没有，则我们使用 Android 位置服务。然后我们只需要与一个LocationTracker类型的对象进行交互，一切都由这个接口完成：
namespace Maps.Droid.LocationService
public interface LocationInterface
void startLocationServices();
void stopLocationServices();
void pauseLocationServices();
void resumeLocationServices();
double getLatitude();
double getLongitude();
bool canGetLocation();
using System;
using Android.App;
using Android.Gms.Location;
using Android.Gms.Common.Apis;
using Android.OS;
using Android.Gms.Maps.Model;
using Android.Widget;
using Android.Locations;
using Android.Gms.Common;
using Android.Gms.Maps;
namespace Maps.Droid.LocationService
public class FusedLocation : Java.Lang.Object, GoogleApiClient.IConnectionCallbacks, GoogleApiClient.IOnConnectionFailedListener, Android.Gms.Location.ILocationListener
private Activity activity;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
private Location currentLocation;
private bool locationAvailable = false;
private GoogleMap map;
public FusedLocation(Activity activity)
this.activity = activity;
mLocationRequest = new LocationRequest();
mLocationRequest.SetInterval(LocationTracker.MIN_TIME_BW_UPDATES);
mLocationRequest.SetFastestInterval(LocationTracker.MIN_TIME_BW_UPDATES / 2);
mLocationRequest.SetSmallestDisplacement(LocationTracker.MIN_DISTANCE_CHANGE_FOR_UPDATES);
mLocationRequest.SetPriority(LocationRequest.PriorityHighAccuracy);
mGoogleApiClient = new GoogleApiClient.Builder(Application.Context)
.AddConnectionCallbacks(this)
.AddOnConnectionFailedListener(this)
.AddApi(LocationServices.API)
.Build();
public Location getCurrentLocation()
return currentLocation;
public void setMap(GoogleMap map)
this.map = map;
public double getLatitude()
return currentLocation.Latitude;
public double getLongitude()
return currentLocation.Longitude;
public void OnResume()
if (mGoogleApiClient.IsConnected)
LocationServices.FusedLocationApi.RequestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
public void OnPause()
// Stop location updates to save battery, but don't disconnect the GoogleApiClient object.
if (mGoogleApiClient.IsConnected)
LocationServices.FusedLocationApi.RemoveLocationUpdates(mGoogleApiClient, this);
public void OnStart()
mGoogleApiClient?.Connect();
public void OnStop()
// only stop if it's connected, otherwise we crash
if (mGoogleApiClient.IsConnected)
mGoogleApiClient?.Disconnect();
public LatLng getLatLng()
return new LatLng(currentLocation.Latitude, currentLocation.Longitude);
public bool canGetLocation()
return locationAvailable && currentLocation != null;
public void OnConnected(Bundle connectionHint)
// Get last known recent location. If the user launches the activity,
// moves to a new location, and then changes the device orientation, the original location
// is displayed as the activity is re-created.
currentLocation = LocationServices.FusedLocationApi.GetLastLocation(mGoogleApiClient);
if (currentLocation != null)
locationAvailable = true;
LocationServices.FusedLocationApi.RequestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
if (map != null)
map.AnimateCamera(CameraUpdateFactory.NewLatLngZoom(getLatLng(), LocationTracker.DEFAULT_ZOOM));
public void OnConnectionSuspended(int cause)
// GoogleApiClient will automatically attempt to restore the connection.
// Applications should disable UI components that require the service, and wait for a call to onConnected(Bundle) to re-enable them
if (cause == GoogleApiClient.ConnectionCallbacks.CauseServiceDisconnected)
Toast.MakeText(activity, "Location Services disconnected. Please re-connect.", ToastLength.Long).Show();
else if (cause == GoogleApiClient.ConnectionCallbacks.CauseNetworkLost)
Toast.MakeText(activity, "Network lost. Please re-connect.", ToastLength.Long).Show();
public void OnLocationChanged(Location location)
currentLocation = location;
public void OnConnectionFailed(ConnectionResult result)
Console.WriteLine("Connection failed: " + result.ToString());
using System;
using Android.OS;
using Android.Locations;
using Android.Runtime;
using Android.App;
using Android.Content;
using Android.Widget;
using Android.Gms.Maps.Model;
using Java.Util.Concurrent;
namespace Maps.Droid.LocationService
public class AndroidLocation : Java.Lang.Object, ILocationListener
// Properties
private LocationManager locMgr;
private Activity activity;
private Location locationGPS, locationNetwork/*, locationPassive*/, currentLocation;
private bool locationAvailable = false;
private Android.Gms.Maps.GoogleMap map;
// UNCOMMNET
// private bool isPassiveEnabled = false; // Gets location from other apps that uses Location Services
// Initializer method (Constructor). Call this method onCreate
public AndroidLocation(Activity activity)
this.activity = activity;
getLocation();
public Location getCurrentLocation()
return currentLocation;
public void setMap(Android.Gms.Maps.GoogleMap map)
this.map = map;
private Location getLocation()
// Use Standard Android Location Service Provider
try
locMgr = activity.GetSystemService(Context.LocationService) as LocationManager;
bool isGPSEnabled = locMgr.IsProviderEnabled(LocationManager.GpsProvider);
// Varying precision, Less power consuming. Combination of WiFi and Cellular data
bool isNetworkEnabled = locMgr.IsProviderEnabled(LocationManager.NetworkProvider);
// UNCOMMENT
// bool isPassiveEnabled = locMgr.IsProviderEnabled(LocationManager.GpsProvider);
// UNCOMMNET
//if (isPassiveEnabled)
// locMgr.RequestLocationUpdates(LocationManager.PassiveProvider, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
// locationPassive = locMgr.GetLastKnownLocation(LocationManager.PassiveProvider);
//
if (isGPSEnabled)
locMgr.RequestLocationUpdates(LocationManager.GpsProvider, LocationTracker.MIN_TIME_BW_UPDATES, LocationTracker.MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
locationGPS = locMgr?.GetLastKnownLocation(LocationManager.GpsProvider);
if (isNetworkEnabled)
locMgr.RequestLocationUpdates(LocationManager.NetworkProvider, LocationTracker.MIN_TIME_BW_UPDATES, LocationTracker.MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
locationNetwork = locMgr?.GetLastKnownLocation(LocationManager.NetworkProvider);
// UNCOMMENT - Method must be implement if PassiveLocation is to be used
// currentLocation = getBestLocation(locationGPS, locationNetwork, locationPassive);
currentLocation = getBestLocation(locationNetwork, locationGPS);
if (currentLocation != null)
locationAvailable = true;
if (map != null)
map.AnimateCamera(Android.Gms.Maps.CameraUpdateFactory.NewLatLngZoom(getLatLng(), LocationTracker.DEFAULT_ZOOM));
catch (Exception e)
Console.WriteLine("ERROR: getLocation() " + e.ToString());
return currentLocation;
// Determines the most recent and/or most accurate location
private Location getBestLocation(Location loc1, Location loc2)
if (loc1 == null || loc2 == null)
return loc1 ?? loc2; // If either location is null then return the not null location
long time1 = TimeUnit.Milliseconds.ToSeconds(loc1.Time);
long time2 = TimeUnit.Milliseconds.ToSeconds(loc2.Time);
long twiceUpdate = (LocationTracker.MIN_TIME_BW_UPDATES / 1000) * 2;
if (Math.Abs(time1 - time2) > twiceUpdate) // If location times are more than twiceUpdate apart
if (time1 > time2) // More time value, most current time
return loc1;
else
return loc2;
else
float accuracy1 = loc1.Accuracy;
float accuracy2 = loc2.Accuracy;
// Smaller the value (meters), the greater the accuracy
if (accuracy1 < accuracy2)
return loc1;
else
return loc2;
public void OnStop()
locMgr = null;
public void OnPause()
locMgr?.RemoveUpdates(this);
public void OnStart()
public void OnResume()
if (locMgr == null || currentLocation == null)
getLocation();
public bool canGetLocation()
return locationAvailable;
public LatLng getLatLng()
return new LatLng(currentLocation.Latitude, currentLocation.Longitude);
public double getLatitude()
return currentLocation.Latitude;
public double getLongitude()
return currentLocation.Longitude;
public void OnLocationChanged(Location location)
currentLocation = getBestLocation(currentLocation, location);
// User disabled a provider
public void OnProviderDisabled(string provider)
getLocation(); // Check if all providers are disabled and pop up alertDialog if they are so
// User enabled a provider
public void OnProviderEnabled(string provider)
getLocation(); // Update all available providers for getting the best provider available
public void OnStatusChanged(string provider, [GeneratedEnum] Availability status, Bundle extras)
using Android.App;
using Android.Gms.Common;
using Android.Gms.Common.Apis;
using Android.Gms.Maps.Model;
using Android.Gms.Maps;
using Android.Locations;
using Android.Content;
using Android.Widget;
namespace Maps.Droid.LocationService
public class LocationTracker
public static long MIN_DISTANCE_CHANGE_FOR_UPDATES = 5; // 5 meters
public static long MIN_TIME_BW_UPDATES = 1000 * 15; // 15 seconds ok, 5 seconds really fast, 30s slow
public static float DEFAULT_ZOOM = 16f;
private bool hasGooglePlayServices;
public GoogleApiClient mGoogleApiClient;
private FusedLocation fusedLocation;
private AndroidLocation androidLocation;
private bool locationIsDisabled;
public LocationTracker(Activity activity)
if (locationIsDisabled = isLocationDisabled(activity))
showSettingsAlert(activity);
else
hasGooglePlayServices = checkPlayServices(activity);
if (hasGooglePlayServices)
fusedLocation = new FusedLocation(activity);
else
androidLocation = new AndroidLocation(activity);
private void showSettingsAlert(Activity activity)
AlertDialog.Builder builder = new AlertDialog.Builder(activity);
builder.SetTitle("Location Services Not Active");
builder.SetMessage("Please enable Location Services and GPS");
builder.SetPositiveButton("OK", delegate
// Show location settings when the user acknowledges the alert dialog
var intent = new Intent(Android.Provider.Settings.ActionLocationSourceSettings);
activity.StartActivity(intent);
);
builder.SetNegativeButton("Cancel", delegate
Toast.MakeText(activity, "Location disabled by user", ToastLength.Short).Show();
);
AlertDialog alertDialog = builder.Create();
alertDialog.SetCanceledOnTouchOutside(false);
alertDialog.Show();
private bool isLocationDisabled(Activity activity)
LocationManager locMgr = activity.GetSystemService(Context.LocationService) as LocationManager;
// More precise, More power consuming
bool isGPSEnabled = locMgr.IsProviderEnabled(LocationManager.GpsProvider);
// Varying precision, Less power consuming. Combination of WiFi and Cellular data
bool isNetworkEnabled = locMgr.IsProviderEnabled(LocationManager.NetworkProvider);
// UNCOMMENT
// bool isPassiveEnabled = locMgr.IsProviderEnabled(LocationManager.PassiveProvider);
// UNCOMMENT
// return !isGPSEnabled && !isNetworkEnabled && !isPassiveEnabled; // True only when the 3 location services are disabled
return !isGPSEnabled && !isNetworkEnabled; // True only when both location services are disabled
// Call this method at OnMapReady callback if initial zooming/animation on user's location is desired
public void setMap(GoogleMap map)
if (locationIsDisabled)
return;
if (hasGooglePlayServices)
fusedLocation.setMap(map);
else
androidLocation.setMap(map);
public void OnResume()
if (locationIsDisabled)
return;
if (hasGooglePlayServices)
fusedLocation.OnResume();
else
androidLocation.OnResume();
public void OnPause()
if (locationIsDisabled)
return;
if (hasGooglePlayServices)
fusedLocation.OnPause();
else
androidLocation.OnPause();
public void OnStart()
if (locationIsDisabled)
return;
if (hasGooglePlayServices)
fusedLocation.OnStart();
else
androidLocation.OnStart();
public void OnStop()
if (locationIsDisabled)
return;
if (hasGooglePlayServices)
fusedLocation.OnStop();
else
androidLocation.OnStop();
private bool checkPlayServices(Activity activity)
GoogleApiAvailability apiAvailability = GoogleApiAvailability.Instance;
int resultCode = apiAvailability.IsGooglePlayServicesAvailable(activity);
if (resultCode == ConnectionResult.Success)
return true;
return false;
public double getLatitude()
if (locationIsDisabled)
return 0;
if (hasGooglePlayServices)
return fusedLocation.getCurrentLocation() == null ? 0.0 : fusedLocation.getLatitude();
else
return androidLocation.getCurrentLocation() == null ? 0.0 : androidLocation.getLatitude();
public double getLongitude()
if (locationIsDisabled)
return 0;
if (hasGooglePlayServices)
return fusedLocation.getCurrentLocation() == null ? 0.0 : fusedLocation.getLongitude();
else
return androidLocation.getCurrentLocation() == null ? 0.0 : androidLocation.getLongitude();
public bool canGetLocation()
if (locationIsDisabled)
return false;
if (hasGooglePlayServices)
return fusedLocation.canGetLocation();
else
return androidLocation.canGetLocation();
public LatLng getLatLng()
if (locationIsDisabled)
return null;
LatLng latlng;
if (hasGooglePlayServices)
latlng = fusedLocation.getLatLng();
else
latlng = androidLocation.getLatLng();
return latlng;
public Location getCurrentLocation()
if (hasGooglePlayServices)
return fusedLocation.getCurrentLocation();
else
return androidLocation.getCurrentLocation();
然后在您的片段或活动上使用它：
在 OnCreate 初始化它：
Location tracker = new LocationTracker(this.Activity);
为生命周期做一个参照：
public override void OnResume()
base.OnResume();
tracker.OnResume();
public override void OnPause()
base.OnPause();
tracker.OnPause();
public override void OnStart()
base.OnStart();
tracker.OnStart();
public override void OnStop()
base.OnStop();
tracker.OnStop();
如果您希望动画在开始时在用户位置进行缩放，那么您必须在拥有 googlemap 时添加这行代码：
tracker.setMap(googleMap); // Invoke this method if zooming/animating to the user's location is desired
在这个解决方案上花了很多天。希望它可以帮助别人！
【讨论】：
以上是关于FusedLocation GoogleApi - 侦听器不得为空 (Xamarin.Android)的主要内容，如果未能解决你的问题，请参考以下文章
FusedLocation 不会触发 android api <= 21 的 locationcallback
FusedLocation Pending Intent 有时在没有位置的情况下调用