Android 如果调用requestLocationUpdates获取用户的新位置，应用程序将崩溃
我正在使用MonoDroid平台开发android应用程序。此应用程序中有两个模块，一个是驾驶员模块，另一个是乘客模块。当乘客预订出租车时，他/她将能够在地图上查看出租车的位置 在驱动程序模块中，我实现了两个类，一个是GPSTracker类，另一个是NorthStarBackgroundService类。（下面给出了这两个类的代码） NorthStarBackgroundService上名为UpdatePosition的方法负责更新数据库中的驾驶员位置，乘客模块从中获取坐标并在地图中显示驾驶员位置。方法UpdatePosition从实现ILocationListener的GPSTracker类获取驱动程序的坐标 正如您在代码中看到的，我已经注释掉了RequestLocationUpdates。每当我运行应用程序而不注释那行代码时，我的应用程序就会崩溃。但当我运行它时，它不会崩溃。我对这个问题一无所知。此外，当驾驶员移动时，位置不会得到更新 可能熟悉单机器人环境的人，请帮我解决这个问题。这是5天，我试图解决这个问题，但我不能做到这一点 我使用网络提供商只是为了获得粗略的位置。我将扩展到全球定位系统供应商，如果这一个完美的工作 GPSTracker的代码Android 如果调用requestLocationUpdates获取用户的新位置，应用程序将崩溃,android,gps,xamarin.android,Android,Gps,Xamarin.android,我正在使用MonoDroid平台开发android应用程序。此应用程序中有两个模块，一个是驾驶员模块，另一个是乘客模块。当乘客预订出租车时，他/她将能够在地图上查看出租车的位置 在驱动程序模块中，我实现了两个类，一个是GPSTracker类，另一个是NorthStarBackgroundService类。（下面给出了这两个类的代码） NorthStarBackgroundService上名为UpdatePosition的方法负责更新数据库中的驾驶员位置，乘客模块从中获取坐标并在地图中显示驾驶员位
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Locations;
using Java.IO;
namespace NorthStar.Driver
{
public class GPSTracker : Service, ILocationListener
{
public readonly Context mContext;
// flag for network status
Boolean isNetworkEnabled = false;
Location location; // location
public double latitude; // latitude
public double longitude; // longitude
public LocationManager locationManager;
public GPSTracker(Context context)
{
this.mContext = context;
getLocation();
}
public Location getLocation()
{
locationManager = (LocationManager)mContext.GetSystemService(Context.LocationService);
// getting network status
isNetworkEnabled = locationManager.IsProviderEnabled(LocationManager.NetworkProvider);
if (isNetworkEnabled)
{
// locationManager.RequestLocationUpdates(LocationManager.NetworkProvider, 1000, 10, this);
if (locationManager != null)
{
location = locationManager.GetLastKnownLocation(LocationManager.NetworkProvider);
if (location != null)
{
latitude = location.Latitude;
longitude = location.Longitude;
}
}
}
return location;
}
/**
* Function to get latitude
* */
public double getLatitude()
{
latitude = location.Latitude;
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude()
{
latitude = location.Longitude;
// return latitude
return longitude;
}
public void OnLocationChanged(Location location)
{
}
public void OnProviderDisabled(String provider)
{
}
public void OnProviderEnabled(String provider)
{
}
public void OnStatusChanged(string provider, Availability status, Bundle extras)
{
}
public override IBinder OnBind(Intent arg0)
{
return null;
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Preferences;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using NorthStar.Driver.Application;
using TheNorthStar.Api.Requests;
using TheNorthStar.Api.Results;
namespace NorthStar.Driver
{
[Service]
public class NorthStarBackgroundService : Service
{
private string driverId;
private System.Timers.Timer timer;
public override IBinder OnBind(Intent intent)
{
return null;
}
public override void OnCreate()
{
base.OnCreate();
timer = new System.Timers.Timer(20000);
timer.Elapsed += TimerElapsed;
}
void TimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
{
ThreadPool.QueueUserWorkItem(UpdatePosition);
}
public override void OnStart(Intent intent, int startId)
{
base.OnStart(intent, startId);
driverId = intent.GetStringExtra("driverId");
timer.Start();
}
public override void OnDestroy()
{
base.OnDestroy();
timer.Stop();
}
private void UpdatePosition(object data)
{
ConnectToSever api = new ConnectToSever(Helper.GetServer(ApplicationContext));
GPSTracker gps = new GPSTracker(ApplicationContext);
var pos = new DriverPosition() { Latitude = gps.latitude, Longitude = gps.longitude, DriverId = driverId };
try
{
api.UpdatePosition(pos);
}
catch
{
Android.Util.Log.Info("EXC_update1", "update driver failed");
}
}
}
}
I/EXC_logstart( 306): **************** starting driver module ****************
I/ActivityManager( 60): Displayed activity MyDriver_Driver.MyDriver_Driver/northstar.driver.Activity1: 6632 ms (total 6632 ms)
D/dalvikvm( 128): GC_EXPLICIT freed 201 objects / 9848 bytes in 188ms
D/dalvikvm( 120): GC_EXTERNAL_ALLOC freed 3163 objects / 207880 bytes in 144ms
D/dalvikvm( 120): GC_EXTERNAL_ALLOC freed 935 objects / 60072 bytes in 172ms
W/KeyCharacterMap( 306): No keyboard for id 0
W/KeyCharacterMap( 306): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
I/ARMAssembler( 60): generated scanline__00000077:03515104_00000000_00000000 [ 33 ipp] (47 ins) at [0x3bce60:0x3bcf1c] in 8041202 ns
I/ActivityManager( 60): Starting activity: Intent { cmp=MyDriver_Driver.MyDriver_Driver/northstar.driver.MainActivity (has extras) }
I/ActivityManager( 60): Displayed activity MyDriver_Driver.MyDriver_Driver/northstar.driver.MainActivity: 1216 ms (total 1216 ms)
E/mono ( 306):
E/mono ( 306): Unhandled Exception: Java.Lang.NullPointerException: Exception of type 'Java.Lang.NullPointerException' was thrown.
E/mono ( 306): at Android.Runtime.JNIEnv.CallNonvirtualObjectMethod (IntPtr jobject, IntPtr jclass, IntPtr jmethod, Android.Runtime.JValue[] parms) [0x00000] in <filename unknown>:0
E/mono ( 306): at Android.Content.ContextWrapper.GetSystemService (System.String name) [0x00000] in <filename unknown>:0
E/mono ( 306): at NorthStar.Driver.GPSTracker.getLocation () [0x00000] in <filename unknown>:0
E/mono ( 306): at NorthStar.Driver.GPSTracker..ctor (Android.Content.Context context) [0x00000] in <filename unknown>:0
E/mono ( 306): at NorthStar.Driver.MainActivity.RequestWork () [0x00000] in <filename unknown>:0
E/mono ( 306): at NorthStar.Driver.MainActivity.<OnCreate>b__2 (System.Object x) [0x00000] in <filename unknown>:0
E/mono ( 306): --- End of managed exception stack trace ---
E/mono ( 306): java.lang.NullPointerException
E/mono ( 306): at android.content.ContextWrapper.getSystemService(ContextWrapper.java:363)
E/mono ( 306): at dalvik.system.NativeStart.run(Native Method)
E/mono ( 306):
D/Zygote ( 33): Process 306 exited cleanly (255)
I/ActivityManager( 60): Process MyDriver_Driver.MyDriver_Driver (pid 306) has died.
I/WindowManager( 60): WIN DEATH: Window{45103638 MyDriver_Driver.MyDriver_Driver/northstar.driver.Activity1 paused=false}
I/WindowManager( 60): WIN DEATH: Window{4511aac0 MyDriver_Driver.MyDriver_Driver/northstar.driver.MainActivity paused=false}
W/ActivityManager( 60): Scheduling restart of crashed service MyDriver_Driver.MyDriver_Driver/northstar.driver.NorthStarBackgroundService in 5000ms
I/ActivityManager( 60): Start proc MyDriver_Driver.MyDriver_Driver for activity MyDriver_Driver.MyDriver_Driver/northstar.driver.Activity1: pid=320 uid=10042 gids={3003, 1015}
I/UsageStats( 60): Unexpected resume of MyDriver_Driver.MyDriver_Driver while already resumed in MyDriver_Driver.MyDriver_Driver
I/ActivityThread( 320): Publishing provider MyDriver_Driver.MyDriver_Driver.__mono_init__: mono.MonoRuntimeProvider
D/dalvikvm( 320): Trying to load lib /data/data/MyDriver_Driver.MyDriver_Driver/lib/libmonodroid.so 0x44edf660
D/dalvikvm( 320): Added shared lib /data/data/MyDriver_Driver.MyDriver_Driver/lib/libmonodroid.so 0x44edf660
E/mono ( 320): WARNING: The runtime version supported by this application is unavailable.
E/mono ( 320): Using default runtime: v2.0.50727
I/monodroid-gc( 320): environment supports jni NewWeakGlobalRef
W/monodroid-gc( 320): GREF GC Threshold: 1800
I/EXC_logstart( 320): **************** starting driver module ****************
W/InputManagerService( 60): Got RemoteException sending setActive(false) notification to pid 306 uid 10042
I/ActivityManager( 60): Displayed activity MyDriver_Driver.MyDriver_Driver/northstar.driver.Activity1: 4214 ms (total 4214 ms)
I/MonoDroid( 320): UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object
I/MonoDroid( 320): at NorthStar.Driver.NorthStarBackgroundService.OnStart (Android.Content.Intent,int) <0x00038>
I/MonoDroid( 320): at Android.App.Service.n_OnStart_Landroid_content_Intent_I (intptr,intptr,intptr,int) <0x00067>
I/MonoDroid( 320): at (wrapper dynamic-method) object.0333e05f-221e-4109-91bd-6a13aa2251bd (intptr,intptr,intptr,int) <0x0003b>
E/mono ( 320):
E/mono ( 320): Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object
E/mono ( 320): at NorthStar.Driver.NorthStarBackgroundService.OnStart (Android.Content.Intent intent, Int32 startId) [0x00000] in <filename unknown>:0
E/mono ( 320): at Android.App.Service.n_OnStart_Landroid_content_Intent_I (IntPtr jnienv, IntPtr native__this, IntPtr native_intent, Int32 startId) [0x00000] in <filename unknown>:0
E/mono ( 320): at (wrapper dynamic-method) object:0333e05f-221e-4109-91bd-6a13aa2251bd (intptr,intptr,intptr,int)
D/Zygote ( 33): Process 320 exited cleanly (1)
I/ActivityManager( 60): Process MyDriver_Driver.MyDriver_Driver (pid 320) has died.
W/ActivityManager( 60): Scheduling restart of crashed service MyDriver_Driver.MyDriver_Driver/northstar.driver.NorthStarBackgroundService in 20000ms
I/WindowManager( 60): WIN DEATH: Window{45127238 MyDriver_Driver.MyDriver_Driver/northstar.driver.Activity1 paused=false}
I/UsageStats( 60): Unexpected resume of com.android.launcher while already resumed in MyDriver_Driver.MyDriver_Driver
W/InputManagerService( 60): Got RemoteException sending setActive(false) notification to pid 320 uid 10042
I/ActivityManager( 60): Start proc MyDriver_Driver.MyDriver_Driver for service MyDriver_Driver.MyDriver_Driver/northstar.driver.NorthStarBackgroundService: pid=327 uid=10042 gids={3003, 1015}
I/ActivityThread( 327): Publishing provider MyDriver_Driver.MyDriver_Driver.__mono_init__: mono.MonoRuntimeProvider
D/dalvikvm( 327): Trying to load lib /data/data/MyDriver_Driver.MyDriver_Driver/lib/libmonodroid.so 0x44edf580
D/dalvikvm( 327): Added shared lib /data/data/MyDriver_Driver.MyDriver_Driver/lib/libmonodroid.so 0x44edf580
E/mono ( 327): WARNING: The runtime version supported by this application is unavailable.
E/mono ( 327): Using default runtime: v2.0.50727
I/monodroid-gc( 327): environment supports jni NewWeakGlobalRef
W/monodroid-gc( 327): GREF GC Threshold: 1800
I/EXC_logstart（306）：****************启动驱动模块****************
I/ActivityManager（60）：显示的活动MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.Activity1:6632毫秒（总计6632毫秒）
D/dalvikvm（128）：GC_显式释放了201个对象/9848字节（188ms）
D/dalvikvm（120）：GC_EXTERNAL_ALLOC在144ms内释放3163个对象/207880字节
D/dalvikvm（120）：GC_EXTERNAL_ALLOC在172ms内释放935个对象/60072字节
W/KeyCharacterMap（306）：没有id为0的键盘
W/KeyCharacterMap（306）：使用默认keymap:/system/usr/keychars/qwerty.kcm.bin
I/ARMAssembler（60）：在8041202纳秒的[0x3bce60:0x3bcf1c]处生成扫描线\uuU00000077:03515104\uU00000000\uU00000000[33 ipp]（47英寸）
I/ActivityManager（60）：启动活动：Intent{cmp=MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.MainActivity（具有附加功能）}
I/ActivityManager（60）：显示的活动MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.Main活动：1216毫秒（总计1216毫秒）
E/mono（306）：
E/mono（306）：引发了未处理的异常：Java.Lang.NullPointerException:类型为“Java.Lang.NullPointerException”的异常。
E/mono（306）：在Android.Runtime.JNIEnv.CallNonvirtualObjectMethod（IntPtr jobject，IntPtr jclass，IntPtr jmethod，Android.Runtime.JValue[]parms）[0x00000]in:0
E/mono（306）：位于Android.Content.ContextWrapper.GetSystemService（System.String名称）[0x00000]中：0
E/mono（306）：位于NorthStar.Driver.GPSTracker.getLocation（）[0x00000]中：0
E/mono（306）：位于NorthStar.Driver.GPSTracker..ctor（Android.Content.Context）[0x00000]中：0
E/mono（306）：位于NorthStar.Driver.MainActivity.RequestWork（）[0x00000]中：0
E/mono（306）：在NorthStar.Driver.MainActivity.b_u 2（System.Object x）[0x00000]中：0
E/mono（306）：--托管异常堆栈跟踪结束---
E/mono（306）：java.lang.NullPointerException
E/mono（306）：位于android.content.ContextWrapper.getSystemService（ContextWrapper.java:363）
E/mono（306）：在dalvik.system.NativeStart.run（本机方法）
E/mono（306）：
D/合子（33）：进程306干净地退出（255）
I/ActivityManager（60）：进程MyDriver\u Driver.MyDriver\u Driver（pid 306）已死亡。
I/WindowManager（60）：赢得死亡：窗口{45103638 MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.Activity1暂停=false}
I/WindowManager（60）：赢得死亡：窗口{4511aac0 MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.main活动暂停=false}
W/ActivityManager（60）：计划在5000ms内重新启动崩溃的服务MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.NorthStarBackgroundService
I/ActivityManager（60）：启动过程MyDriver\u Driver.MyDriver\u活动的驱动程序MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.Activity1:pid=320 uid=10042 gids={30031015}
I/UsageStats（60）：MyDriver\u Driver.MyDriver\u Driver的意外恢复，但已在MyDriver\u Driver.MyDriver\u Driver中恢复
I/ActivityThread（320）：发布提供程序MyDriver\u Driver.MyDriver\u Driver.\uuuu mono\u init\uuuuu:mono.mono运行时提供程序
D/dalvikvm（320）：尝试加载lib/data/data/MyDriver\u Driver.MyDriver\u Driver/lib/libmonodroid.so 0x44edf660
D/dalvikvm（320）：添加了共享lib/data/data/MyDriver\u Driver.MyDriver\u Driver/lib/libmonodroid.so 0x44edf660
E/mono（320）：警告：此应用程序支持的运行时版本不可用。
E/mono（320）：使用默认运行时：v2.0.50727
I/monodroid gc（320）：环境支持jni NewWeakGlobalRef
W/单机器人gc（320）：GREF gc阈值：1800
I/EXCèU logstart（320）：******************启动驱动器模块****************
W/InputManagerService（60）：获取远程异常，向pid 306 uid 10042发送setActive（false）通知
I/ActivityManager（60）：显示的活动MyDriver\u Driver.MyDriver\u Driver/northstar.Driver.Activity1:4214毫秒（总计4214毫秒）
I/MonoDroid（320）：未处理的异常：System.NullReferenceException:对象引用未设置为对象的实例
I/MonoDroid（320）：位于NorthStar.Driver.NorthStarBackgroundService.OnStart（一个
_locationManager = (LocationManager)GetSystemService(LocationService);
Location lastKnownLocation = _locationManager.GetLastKnownLocation(bestProvider);
if (lastKnownLocation != null) ... // Set your instance variable for location.
// You can set the thresholds that suit you here.
_locationManager.RequestLocationUpdates(bestProvider, 5000, 2, this);
public void OnLocationChanged(Location location)
{
// Update your instance variable for location
}