Hi I have a map application where I need to show all the markers fetched from database onto map it is don on pressing a button. It shows perfectly for the pressing once but if i press the button twice then it gives ConcurrentModificationException. Any help would be appreciated. Here is my asynctask class for loading the markers onto map from database.
class LoadMarkers extends AsyncTask<Void , Void , Void>
{
ProgressDialog progressDialog;
@Override
protected void onPreExecute()
{
progressDialog = ProgressDialog.show(DemoAccidentReport.this , "Loading Markers" , "Please wait..." , true , false);
Log.d("after progress dialog onPreExecute()------->" , "onPreExecute()");
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params)
{
Log.d("after progress dialog doInBackground()------->" , "doInBackground()");
try
{
db = openOrCreateDatabase("LocationFetch.db", MODE_PRIVATE , null);
cursor = db.rawQuery("SELECT * FROM user" , null);
drawableOne = getResources().getDrawable(R.drawable.location_blue);
final List<Overlay> mapOverlays = mapView.getOverlays();
//helloItemizedOverlay = new HelloItemizedOverlay(drawableOne , DemoAccidentReport.this);
//helloItemizedOverlay = new HelloItemizedOverlay(drawableOne);
popUpitemizedOverlay = new MyPopupItemizedOverlay(drawableOne, mapView);
Log.d("after progress dialog doInBackground() One------->" , "doInBackground()");
//itemizedOverlay = new CustomItemizedOverlay<CustomOverlayItem>(drawableOne , mapView);
Log.d("after progress dialog doInBackground()Two------->" , "doInBackground()");
while(cursor.moveToNext())
{
int dataID = cursor.getColumnIndex("id");
String dataString = cursor.getString(0);
Log.d("ID DATA FROM DATABASE---->" , dataString);
String dataNAME = cursor.getString(1).toString().trim();
Log.d("NAME DATA FROM DATABASE---->", dataNAME);
String dataDESCRIPTION = cursor.getString(6);
Log.d("DESCRIPTION--------->" , dataDESCRIPTION);
String dataLAT = cursor.getString(2).toString().trim();
//Log.d("LAT DATA FROM DATABASE----->" , dataLAT);
double latitude = Double.parseDouble(dataLAT)*1000000;
Log.d("LATDOUBLE DATA FROM DATABASE----->" , latitude+"");
String dataLON = cursor.getString(3).toString().trim();
//Log.d("LONDOUBLE DATA FROM DATABASE----->" , dataLON);
double longitude = Double.parseDouble(dataLON)*1000000;
Log.d("LONDOUBLE DATA FROM DATABASE----->" , longitude+"");
//Image at column 4
//byte[] picture = cursor.getBlob(4);
ByteArrayInputStream inputStream = new ByteArrayInputStream(cursor.getBlob(4));
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
//showLatLon(latitude , longitude , dataNAME);
//ArrayList<OverlayItem> items = new ArrayList<OverlayItem>();
//OverlayItem[] markerItem = {new OverlayItem(new GeoPoint(latitude, longitude) , ""+dataNAME , ""+dataString)};
//OverlayItem markerItem = new OverlayItem(new GeoPoint((int)(latitude *1E6), (int)(longitude *1E6)) , ""+dataNAME , ""+dataString);\
//helloItemizedOverlay.addOverlay(overlayItem);
//mapView.getOverlays().add(helloItemizedOverlay);
//mapOverlays.add(helloItemizedOverlay);
/*CustomOverlayItem overlayItem = new CustomOverlayItem(new GeoPoint((int)(latitude *1E6), (int)(longitude *1E6)), ""+dataLAT , ""+dataLON , R.drawable.icon);
itemizedOverlay.addOverlay(overlayItem);
mapOverlays.add(itemizedOverlay);*/
//-------WORKING POPUP ONLY TITLE AND DESCRIPTION------//
OverlayItem overlayItem = new OverlayItem(new GeoPoint((int)latitude , (int)longitude) , ""+dataNAME , ""+dataDESCRIPTION /*null*/ );
popUpitemizedOverlay.addOverlay(overlayItem);
mapView.getOverlays().add(popUpitemizedOverlay);
mapOverlays.add(popUpitemizedOverlay);
}
}catch(SQLException e)
{
e.printStackTrace();
}finally
{
cursor.close();
}
db.close();
return null;
}
@Override
protected void onPostExecute(Void result)
{
progressDialog.dismiss();
super.onPostExecute(result);
}
}
这是 logcat 的异常，它向我抛出了 Concurrent ModificationException 异常，在按下两次按钮时，即使它没有显示第一个标记，也只显示第二个标记：
04-10 14:05:14.898: E/AndroidRuntime(8991): FATAL EXCEPTION: main
04-10 14:05:14.898: E/AndroidRuntime(8991): java.util.ConcurrentModificationException
04-10 14:05:14.898: E/AndroidRuntime(8991): at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:576)
04-10 14:05:14.898: E/AndroidRuntime(8991): at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java:41)
04-10 14:05:14.898: E/AndroidRuntime(8991): at com.google.android.maps.MapView.onDraw(MapView.java:530)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.View.draw(View.java:6880)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.View.draw(View.java:6986)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.widget.FrameLayout.draw(FrameLayout.java:357)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.widget.ScrollView.draw(ScrollView.java:1683)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.View.draw(View.java:6883)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.widget.FrameLayout.draw(FrameLayout.java:357)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.View.draw(View.java:6883)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.widget.FrameLayout.draw(FrameLayout.java:357)
04-10 14:05:14.898: E/AndroidRuntime(8991): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1940)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewRoot.draw(ViewRoot.java:1527)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewRoot.performTraversals(ViewRoot.java:1264)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.view.ViewRoot.handleMessage(ViewRoot.java:1865)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.os.Handler.dispatchMessage(Handler.java:99)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.os.Looper.loop(Looper.java:130)
04-10 14:05:14.898: E/AndroidRuntime(8991): at android.app.ActivityThread.main(ActivityThread.java:3687)
04-10 14:05:14.898: E/AndroidRuntime(8991): at java.lang.reflect.Method.invokeNative(Native Method)
04-10 14:05:14.898: E/AndroidRuntime(8991): at java.lang.reflect.Method.invoke(Method.java:507)
04-10 14:05:14.898: E/AndroidRuntime(8991): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
04-10 14:05:14.898: E/AndroidRuntime(8991): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
04-10 14:05:14.898: E/AndroidRuntime(8991): at dalvik.system.NativeStart.main(Native Method)