ConcurrentModificationException

Question

I would like to share a fairly common error from Google Play Console (Android):

java.util.ConcurrentModificationException: 

  at java.util.HashMap$HashIterator.nextNode (HashMap.java:1442)
  at java.util.HashMap$KeyIterator.next (HashMap.java:1466)
  at com.shephertz.app42.gaming.multiplayer.client.WarpClient.onResponse (WarpClient.java:506)
  at com.shephertz.app42.gaming.multiplayer.client.MessageDispatchThread.run (MessageDispatchThread.java:48)

What can this be related to?

I use App42MultiPlayerGamingSDK.jar (version 2.3).

Code:

public void quickGame() {
    ...
    initAppWarp();
    addListeners();
    connectAppWarp();
}

private void initAppWarp() {
    if (warpClient == null) {
        try {
            WarpClient.initialize(apiKey, secretKey);
            warpClient = WarpClient.getInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

private void addListeners() {
    if (warpClient != null) {
        if (connectionListener == null) {
            connectionListener = new ConnectionListener(this);
            warpClient.addConnectionRequestListener(connectionListener);
        }
        if (roomListener == null) {
            roomListener = new RoomListener(this);
            warpClient.addRoomRequestListener(roomListener);
        }
        if (zoneListener == null) {
            zoneListener = new ZoneListener(this);
            warpClient.addZoneRequestListener(zoneListener);
        }
        if (notificationListener == null) {
            notificationListener = new NotificationListener(this);
            warpClient.addNotificationListener(notificationListener);
        }
    }
}

private void connectAppWarp() {
    if (warpClient != null) {
        warpClient.connectWithUserName(myId);
    }
}

//-----------------------------------------
//-----------------------------------------

private void onConnectDone(boolean status) {
    ...
    warpClient.joinRoomWithProperties(properties);
}

private void onJoinRoomDone(RoomEvent event) {
    if (event.getResult() == WarpResponseResultCode.SUCCESS) {
        ...
        warpClient.subscribeRoom(roomId);
    } else if (event.getResult() == WarpResponseResultCode.RESOURCE_NOT_FOUND) {
        ...
        warpClient.createRoom("game", "owner", 2, properties);
    }
}

private void onRoomCreated(String roomId){
    ...
    warpClient.joinRoom(roomId);
}

private void onRoomSubscribed(String roomId) {
    ...
    warpClient.getLiveRoomInfo(roomId);
}

public void sendMessage(byte[] msgBuf) {
    warpClient.sendPrivateUpdate(opponentId, msgBuf);
}

//-----------------------------------------
//-----------------------------------------

public void leaveGame() {
    if (warpClient != null && state == ConnectedState.JOINED_ROOM) {
        warpClient.unsubscribeRoom(roomId);
        warpClient.leaveRoom(roomId);
        if (roomId != null && roomId.length() > 0) {
             warpClient.deleteRoom(roomId);
        }
    }
    warpClient.disconnect();
}

@Override
public void onDisconnectDone(ConnectEvent event) {
    removeListeners();
}

private void removeListeners() {
    if (warpClient != null) {
        warpClient.removeConnectionRequestListener(connectionListener);
        warpClient.removeRoomRequestListener(roomListener);
        warpClient.removeZoneRequestListener(zoneListener);
        warpClient.removeNotificationListener(notificationListener);
        connectionListener = null;
        roomListener = null;
        zoneListener = null;
        notificationListener = null;
    }
}

Answer 1

I solved this problem! Technical support offered a solution.

I stopped removing listeners in the project. I removed the removeListeners() method from the code.

http://forum.shephertz.com/?qa=11075/concurrentmodificationexception-causing-app-crashes&show=11075#q11075