在我的应用程序中,我有一个获取设备位置的服务,并将此信息传递给一个线程。我还需要将sharedpreferences值传递给线程。当我这样做时,应用程序会收到运行时错误并强制关闭。如果我不试图获得该值,其他所有工作都会传递给线程。
我认为这是因为onLocationChanged()
没有上下文,任何人都可以帮忙吗?
服务代码:
public class TrackGPS extends Service implements LocationListener{
LocationManager lm;
LocationListener loc;
public SharedPreferences sharedpreferences;
public static final String US = "usersettings";
public String prefPhoneNum = "prefPhoneNum";
double lat = 0, lon = 0, alt = 0, acc = 0;
long tim = 0;
public void onCreate() {
super.onCreate();
/* Calling the value works fine here but can't pass to onLocationChanged() */
// sharedpreferences = getSharedPreferences(US, MODE_WORLD_READABLE);
// prefPhoneNum = sharedpreferences.getString("prefPhoneNum" , "");
lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
loc = new TrackGPS();
enableGPS();
onDestroy();
stopSelf();
}
public void enableGPS() {
new CountDownTimer(120000, 1000) { //120 seconds
public void onTick(long millisUntilFinished)
{
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, loc);
}
public void onFinish()
{
lm.removeUpdates(loc);
}
}.start();
}
@Override
public void onLocationChanged(Location location) {
lat = location.getLatitude();
lon = location.getLongitude();
alt = location.getAltitude();
acc = location.getAccuracy();
tim = location.getTime();
sharedpreferences = getSharedPreferences(US, MODE_WORLD_READABLE);
prefPhoneNum = sharedpreferences.getString("prefPhoneNum" , "");
Thread cThread = new Thread(new SocketsClient(lat, lon, alt, acc, tim, prefPhoneNum));
cThread.start();
}
@Override
public void onProviderDisabled(String provider) { }
@Override
public void onProviderEnabled(String provider) { }
@Override
public void onStatusChanged(String provider, int status, Bundle extras) { }
@Override
public IBinder onBind(Intent intent) { return null; }
public void onDestroy() { super.onDestroy(); }
}
Logcat错误:
D/LocationManager(3912): requestLocationUpdates: provider = gps, listener = accel.working.TrackGPS@4628bce0
D/GpsLocationProvider(96): setMinTime 0
D/GpsLocationProvider(96): startNavigating
D/GpsLocationProvider(96): TTFF: 3227
D/AndroidRuntime(912): Shutting down VM
W/dalvikvm(3912): threadid=1: thread exiting with uncaught exception (group=0x400259f8)
E/AndroidRuntime(3912): FATAL EXCEPTION: main
E/AndroidRuntime(3912): java.lang.NullPointerException
E/AndroidRuntime(3912): at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:146)
E/AndroidRuntime(3912): at accel.working.TrackGPS.onLocationChanged(TrackGPS.java:63)
E/AndroidRuntime(3912): at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:191)
E/AndroidRuntime(3912): at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:124)
E/AndroidRuntime(3912): at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:140)
E/AndroidRuntime(3912): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(3912): at android.os.Looper.loop(Looper.java:144)
E/AndroidRuntime(3912): at android.app.ActivityThread.main(ActivityThread.java:4937)
E/AndroidRuntime(3912): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(3912): at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime(3912): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
E/AndroidRuntime(3912): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
E/AndroidRuntime(3912): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分:1)
这是你的第一个问题
loc = new TrackGPS();
永远不要创建活动或服务的实例或任何其他类new
的类。在那里,甚至不值得进入更多的代码。
但即便如此,这个
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, loc);
只应调用一次。它会在每次获取更新时调用onLocationChanged。你不需要继续打电话。
编辑:哦,我知道你在那里做什么,而且没有必要。您可以在onCreate中请求LocationUpdates。
另外,
onDestroy();
你永远不应该自己调用这个方法。这是由框架调用的。不要这样做
最后,你正在打电话
stopSelf();
在调用requestlocationupdates的线程之前
。当然会导致未定义的行为。您正在停止该服务,而不会取消注册该侦听器。
答案 1 :(得分:0)
根据你从未做过的这句话,这是错的吗?
final Handler mHandler_AboutGeneric = new Handler();