停止位置服务

Question

每当我尝试停止在android上的位置服务我得到一个NullPointerException。任何人都有一些关于如何做到这一点的提示？我想实现一些onstop（）和ondestroy（）方法的活动。这里是我的服务代码：

LocationService.Java

包com.storetab;

public class LocationService extends Service { 
static LocationManager locationManager; 
static Location lastknown; 
final static String MY_ACTION = "MY_ACTION"; 
static LocationListener ll; 
@Override 
public IBinder onBind(Intent arg0) { 
// TODO Auto-generated method stub 
return null; 
} 

@Override 
public int onStartCommand(Intent intent, int flags, int startId){ 

final Criteria criteria = new Criteria(); 
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE); 
criteria.setAccuracy(Criteria.ACCURACY_FINE); 
criteria.setPowerRequirement(Criteria.POWER_LOW); 
criteria.setAltitudeRequired(false); 
criteria.setBearingRequired(false); 
criteria.setSpeedRequired(false); 
criteria.setCostAllowed(true); 
locationManager.getBestProvider(criteria, true); 
ll = new MyLocListener(); 


locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, ll); 

lastknown = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER); 
Log.d("Teste","lastknown"); 
Intent intent1 = new Intent(); 
intent.putExtra("location1", lastknown); 
intent.setAction(MY_ACTION); 
sendBroadcast(intent1); 
Log.d("broadcastlast","lastknown"); 
return START_STICKY; 

} 

private class MyLocListener implements LocationListener { 
public void onLocationChanged(Location location) { 



    } 

public void onProviderDisabled(String arg0) { 
// TODO Auto-generated method stub 
Log.d("1Provider DIsabled", "Provider Disabled"); 
} 

public void onProviderEnabled(String provider) { 
// TODO Auto-generated method stub 
Log.d("1Provider Enabled", "Provider Enabled"); 
} 

public void onStatusChanged(String provider, int status, Bundle extras) { 
// TODO Auto-generated method stub 
Log.d("1Provider Changed", "Service Status Changed"); 
} 

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

Answer 1

在你onStartCommand()你有这样的代码：

LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE); 

这将创建一个局部变量称为locationManager，这皮类变量声明了上面在班上名列前茅：

static LocationManager locationManager; 

该静态类变量locationManager从来没有设置任何东西，所以它是null在onDestroy()。

为了解决这个问题，只要它更改为在此onStartCommand()：

locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);