java.util.ConcurrentModificationException On MapView

Question

fellas

I am facing very strange issue from many days. I am trying to update overlay frequently. So sometime I am getting "java.util.ConcurrentModificationException" when I touch on map or sometime getting when map trying to update overlay But I am not finding perfect line which on this error is coming.

02-17 14:56:01.621: W/dalvikvm(3653): threadid=1: thread exiting with uncaught exception (group=0x40015560)
02-17 14:56:01.631: E/AndroidRuntime(3653): FATAL EXCEPTION: main
02-17 14:56:01.631: E/AndroidRuntime(3653): java.util.ConcurrentModificationException
02-17 14:56:01.631: E/AndroidRuntime(3653):     at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:576)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java:41)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at com.google.android.maps.MapView.onDraw(MapView.java:530)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.View.draw(View.java:6880)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.View.draw(View.java:6883)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.widget.FrameLayout.draw(FrameLayout.java:357)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.View.draw(View.java:6883)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.widget.FrameLayout.draw(FrameLayout.java:357)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.View.draw(View.java:6883)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.widget.FrameLayout.draw(FrameLayout.java:357)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1862)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewRoot.draw(ViewRoot.java:1522)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewRoot.performTraversals(ViewRoot.java:1258)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.os.Looper.loop(Looper.java:130)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at android.app.ActivityThread.main(ActivityThread.java:3683)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at java.lang.reflect.Method.invokeNative(Native Method)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at java.lang.reflect.Method.invoke(Method.java:507)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-17 14:56:01.631: E/AndroidRuntime(3653):     at dalvik.system.NativeStart.main(Native Method)

I am using Balloon Overlay

I think it is throwing error on "mapview.getOverlay()" because it is calling 4-5 times in 1 seconds..

Thanks,

CapDroid

here is code flow.. My Thread code....

Thread connection = new Thread(){
        public void run() {
            try {

                while (my condition)
                {
                    try 
                    {
                                        //This method should be call every seconds
                        updateMethod();
                    } 
                    catch (Exception e) 
                    {
                        e.printStackTrace();
                        break;
                    }
                } 
            } 
            catch (Exception e) 
            {

            }
        }
    };

Here is My updateMethod(); in this code hashmapOverlay is HashMap like as below

 public static Map<String,MyItemizedOverlay> hashmapOverlay;

 public void updateMethod()
{

                    if(hashmapOverlay.containsKey(id))
                        {
                            mapview.getOverlays().remove(hashmapOnlineFriendsOverlay.get(id));
                        }
                    MyItemizedOverlay mMyItemizedOverlay = new MyItemizedOverlay(drawable, mapview);
                        OverlayItem overlayItem = new OverlayItem(gp,title ,snippet);
                        mMyItemizedOverlay.addOverlay(overlayItem); 
                    hashmapOverlay.put(id, mMyItemizedOverlay);
                    addOverlayMethod(mActivity, mapView, mMyItemizedOverlay);   

}

Here is my addOverlayMethod

addOverlayMethod(Activity mActivity, final MapView mapView, final Object mObject)
{
    mActivity.runOnUiThread(new Runnable(){

        @Override
        public void run()
        {

                try {
                    MyItemizedOverlay overlay = (MyItemizedOverlay) mObject;
                    mapView.getOverlays().add(overlay);
                } catch (Exception e)
                {}              

        }
    });
}

Can I see where you are trying to modify/update your Overlay? — Lalit Poptani
– Lalit Poptani, Commented Feb 17, 2012 at 10:02
there are many class and overlay packages so i can't show all here.. thanks brother — Niranj Patel
– Niranj Patel, Commented Feb 17, 2012 at 10:07
Make sure that you are trying to refresh or update your Overlay from UI thread itself and not from Non-UI thread. — Lalit Poptani
– Lalit Poptani, Commented Feb 17, 2012 at 10:08
@LalitPoptani Hello I edited my question with code can you help me now? — Niranj Patel
– Niranj Patel, Commented Feb 20, 2012 at 6:01

Matt · Accepted Answer · 2012-02-17 10:28:51Z

2

In order to avoid ConcurrentModificationException simply copy your collection in any of the following cases:

before iterating over a collection
before passing it into an API

At first glance, this might seem like overkill but it will save you a lot of headache later on. Copying is simple, just call new ArrayList<YourClass>(existingList).

answered Feb 17, 2012 at 10:28

Matt

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5 Comments

Niranj Patel Over a year ago

hi @Matt I also did it but I am not sure about it will 100% solved my issue or not?

Matt Over a year ago

If you no longer get any ConcurrentModifictionException, well, yes :)

Niranj Patel Over a year ago

I think it is throwing error on "mapview.getOverlay()" because it is calling 4-5 times in 1 seconds.. is it possible?

Matt Over a year ago

In general this error happens if you iterate over a collection and at the same time the collection changes. So, theoretically yes, but I don't know anything about the concrete implementation details of map overlays. I think the best solution would be, if you could provide a sample project which reproduces the error so that we can debug it.

Niranj Patel Over a year ago

Hello I edited my question with code can you help me now? @Matt

Samir Mangroliya · Accepted Answer · 2012-02-17 10:07:59Z

1

I think You use Thread and its create Concurrency So use Syncronized(MainActivity.this) in Your Run Method....And Use Vector Instead of List Because Vector is Syncronized...Its Works for me...

edited Feb 17, 2012 at 10:07

answered Feb 17, 2012 at 9:58

Samir Mangroliya

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9 Comments

Niranj Patel Over a year ago

there are many overlay and all are updating from service class I also put in runOnUiThread..

Samir Mangroliya Over a year ago

@CapDroid I have same issue and its occure some times so i do R&D and get this final solution....

Niranj Patel Over a year ago

and one more thing sometime it will be update 4-5 time in 1 seconds

Lalit Poptani Over a year ago

@Samir Vector is deprecated.

Lalit Poptani Over a year ago

@Samir you can check Why Java Vector class is considered obsolete or deprecated?

|

Lalit Poptani · Accepted Answer · 2012-02-20 06:31:22Z

1

Well, it seems that in your updateMethod() you are still trying to Update your UI from a Non-UI thread by

mapview.getOverlays().remove(hashmapOnlineFriendsOverlay.get(id));

So, try to execute this part of your code inside the RunOnUiThread and try. Hope this would work.

UPDATE:

Also, why you are trying to add and remove your Overlay everything, you don't need to do that just try to update your Overlay and invalidate it. Have a look at this example.

edited Feb 20, 2012 at 6:31

answered Feb 20, 2012 at 6:10

Lalit Poptani

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3 Comments

Niranj Patel Over a year ago

I also tried it when I put it then my application is hang.. bcz that method is calling manytimes at time

Niranj Patel Over a year ago

one more thing this error is coming when i touch on map or any overlay otherwise it is working fine

Niranj Patel Over a year ago

Hello @Lalit Poptani I put RunOnUiThread only for remove line but still getting error..and already seen that example but i also want popup when user touch on overlay so .......etc

Mo Kargas · Accepted Answer · 2012-02-25 05:23:15Z

1

I'm not sure about the overlay management, but the way I see it, you're modifying your HashMap with HashMap.put on a non-UI thread (in UpdateMethod), when it's no doubt being iterated over or used elsewhere in the app - probably when still requesting new Overlays as you move your map around.

If you read the docs, it says this will cause a ConcurrentModificationException. Instead, try using a ConcurrentHashMap, or restructure your code to update the hashmap on the main thread where it is being used.

answered Feb 25, 2012 at 5:23

Mo Kargas

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Comments

Mohammed Azharuddin Shaikh · Accepted Answer · 2012-02-27 07:01:22Z

1

+50

ya, you can do a work around, step as follow.

Make a Pendingnotification class(modication detail).
Make a list of the Pendingnotification.
when any notification receive dnt modify it directly, Collect all the modification and put stack(Pendingnotification class) ie. add it in Pendingnotification list.
now one by one modify the object and remove the same object when its work done.

same way follow untill Pendingnotification List become empty.

And also note that any modification must be perform in UI Thread not in NonUI Thread

answered Feb 27, 2012 at 7:01

Mohammed Azharuddin Shaikh

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