Question

我想要做的是我可以开始的服务。当我启动服务时，它应该监听gps位置更新。所以我实施了以下服务：

public class TrackingService extends Service {

    protected LocationManager locationManager;
    protected PendingIntent locationReceiverPendingIntent;
    protected Intent locationIntent;

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        locationIntent = new Intent(this, LocationReceiver.class);
        locationReceiverPendingIntent = PendingIntent.getBroadcast(this, 0, locationIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        Criteria criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE); // FINE tries to use GPS

        long minimumWaitBetweenLocationUpdatesInMilliSeconds = 15000;
        float minimumLoctaionChangeInMeters = 50;
        locationManager.requestLocationUpdates(minimumWaitBetweenLocationUpdatesInMilliSeconds, minimumLoctaionChangeInMeters, criteria, locationReceiverPendingIntent);    
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        locationManager.removeUpdates(locationReceiverPendingIntent);
    }
}

我在我的开始活动中启动此服务：

@Override
protected void onResume() {
    super.onResume();
    Intent serviceIntent = new Intent(this, TrackingService.class);     
    this.startService(serviceIntent);
}

LocationReceiver是一个BroadcastReceiver。我在行上使用以下代码locationManager.requestLocationUpdates(minimumWaitBetweenLocationUpdatesInMilliSeconds, minimumLoctaionChangeInMeters, criteria, locationReceiverPendingIntent);得到以下NullPointerExpection：

VM不提供监视器信息
  线程[＆lt; 1＆gt; main]（Suspended（例外RuntimeException））
    ActivityThread.handleCreateService（ActivityThread $ CreateServiceData）   行：2539 ActivityThread.access $ 1600（ActivityThread，   ActivityThread $ CreateServiceData）line：141
    ActivityThread $ H.handleMessage（消息）行：1316
    ActivityThread $ H（Handler）.dispatchMessage（Message）行：99     Looper.loop（）行：137 ActivityThread.main（String []）行：5041
    Method.invokeNative（Object，Object []，Class，Class []，Class，int，   boolean）line：not available [native method] Method.invoke（Object，   对象...）行：511 ZygoteInit $ MethodAndArgsCaller.run（）行：793
    ZygoteInit.main（String []）行：560 NativeStart.main（String []）   line：not available [native method]

原因可能是什么？

Answer 1

您需要初始化locationManager

locationManager = getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(minimumWaitBetweenLocationUpdatesInMilliSeconds, minimumLoctaionChangeInMeters, criteria, locationReceiverPendingIntent);

locationManager.requestLocationUpdates（）导致NullpointerException

1 个答案: