使用谷歌地图和服务绘制多边形

• Z时代
• 2024-01-10
• 分类：问答

你好，我试图在开车时画一条简单的线条。我想在后台收集位置数据，这就是为什么我使用服务。在服务端的代码如下所示：使用谷歌地图和服务绘制多边形

// 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发送纬度和经度，我在我的FragmentActivity阅读本。

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(); 
     } 
    } 
} 

我可以读取片段上的经度和纬度，所以它看起来像一切正常，但它并没有画出一条线。 但期权的价值就像如下：

D/LATLANG: [email protected]

而且它还有我一个错误：

W/System.err: java.lang.NullPointerException

的ArrayList<LatLng> points;被初始化onCreateView

我与这几个小时挣扎，我找不到解决方案。 我会非常感谢您的帮助。

的错误信息是：

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 [email protected] 
                       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)  

回答：

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

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