使用谷歌地圖和服務繪製多邊形

Question

你好，我試圖在開車時畫一條簡單的線條。我想在後臺收集位置數據，這就是爲什麼我使用服務。在服務端的代碼如下所示：

// THIS IS FOR GPS 

private class LocationListener implements android.location.LocationListener{ 

    Location mLastLocation; 

    public LocationListener(String provider){ 

     Log.e(TAG, "LocationListener " + provider); 
     mLastLocation = new Location(provider); 
    } 

    @Override 
    public void onLocationChanged(Location location) { 

     Intent mapIntent = new Intent(); 

     Log.e(TAG, "onLocationChanged: " + location); 
     mLastLocation.set(location); 

     double latitude = location.getLatitude(); 
     double longitude = location.getLongitude(); 

     mapIntent.putExtra("Latitude", latitude); 
     mapIntent.putExtra("Longitude", longitude); 

     mapIntent.setAction(MAP_ACTION); 
     sendBroadcast(mapIntent); 

    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 

     Log.e(TAG, "onStatusChanged: " + provider); 
    } 

    @Override 
    public void onProviderEnabled(String provider) { 

     Log.e(TAG, "onProviderEnabled: " + provider); 

    } 

    @Override 
    public void onProviderDisabled(String provider) { 

     Log.e(TAG, "onProviderDisabled: " + provider); 
    } 
} 

LocationListener[] mLocationListeners = new LocationListener[] { 
     new LocationListener(LocationManager.GPS_PROVIDER), 
     new LocationListener(LocationManager.NETWORK_PROVIDER) 
}; 

private void initializeLocationManager() { 
    Log.e(TAG, "initializeLocationManager"); 
    if (mLocationManager == null) { 
     mLocationManager = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE); 
    } 
} 

我使用putExtra發送緯度和經度，我在我的FragmentActivity閱讀本。

class MapBroadcast extends BroadcastReceiver{ 

    @Override 
    public void onReceive(Context context, Intent intent) { 

     Bundle extras = intent.getExtras(); 
     LatLng temp = new LatLng(extras.getDouble("Latitude"),extras.getDouble("Longitude")); 


     points.add(temp); 

     try { 

      googleMap.clear(); 

      PolylineOptions options = new PolylineOptions().width(5).color(Color.BLUE).geodesic(true); 
      for (int i = 0; i < points.size(); i++) { 
       LatLng point = points.get(i); 
       options.add(point); 

       Log.d("LATLONG", String.valueOf(options)); 
      } 

      if (options != null) 
      { 
       line = googleMap.addPolyline(options); 
      } 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

    } 
} 

我可以讀取片段上的經度和緯度，所以它看起來像一切正常，但它並沒有畫出一條線。 但期權的價值就像如下：

D/LATLANG: com.google.android.gms.maps.model.PolylineOptions@21ea8168

而且它還有我一個錯誤：

W/System.err: java.lang.NullPointerException

的ArrayList<LatLng> points;被初始化onCreateView

我與這幾個小時掙扎，我找不到解決方案。 我會非常感謝您的幫助。

的錯誤信息是：

12-02 23:19:35.079 5423-5423/com.example.mattkopacz.obdmenu E/AndroidRuntime: FATAL EXCEPTION: main 
                      Process: com.example.mattkopacz.obdmenu, PID: 5423 
                      java.lang.RuntimeException: Error receiving broadcast Intent { act=MAP_ACTION flg=0x10 (has extras) } in com.example.mattkopacz.obdmenu.Menu1$MapBroadcast@21f0fb18 
                       at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:782) 
                       at android.os.Handler.handleCallback(Handler.java:733) 
                       at android.os.Handler.dispatchMessage(Handler.java:95) 
                       at android.os.Looper.loop(Looper.java:146) 
                       at android.app.ActivityThread.main(ActivityThread.java:5653) 
                       at java.lang.reflect.Method.invokeNative(Native Method) 
                       at java.lang.reflect.Method.invoke(Method.java:515) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
                       at dalvik.system.NativeStart.main(Native Method) 
                      Caused by: java.lang.NullPointerException 
                       at com.example.mattkopacz.obdmenu.Menu1$MapBroadcast.onReceive(Menu1.java:260) 
                       at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:772) 
                       at android.os.Handler.handleCallback(Handler.java:733)  
                       at android.os.Handler.dispatchMessage(Handler.java:95)  
                       at android.os.Looper.loop(Looper.java:146)  
                       at android.app.ActivityThread.main(ActivityThread.java:5653)  
                       at java.lang.reflect.Method.invokeNative(Native Method)  
                       at java.lang.reflect.Method.invoke(Method.java:515)  
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)  
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)  
                       at dalvik.system.NativeStart.main(Native Method)  

Answer 1

你不需要單獨添加每個經緯度而是可以使用polyOptions.addAll(points)添加整個列表在一起。

final PolylineOptions polyOptions = new PolylineOptions(); 
     polyOptions.color(Color.BLUE); 
     polyOptions.width(5); 
     polyOptions.geodesic(true); 
     polyOptions.jointType(ROUND); 
     polyOptions.addAll(points); 
     googleMap.addPolyline(polyOptions);