How to resolve "The content of the adapter has changed but ListView did not receive a notification” exception

Question

I found a lot of questions on the same topic. But I am unable to figure out what I am doing wrong here.

Exception: "The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread"

I have a TextWatcher to my AutoCompleteTextView. I am trying to update the dropdown list when the text changes. I am fetching data for the dropdown from two different sources. And each one of them running inside different threads.

mTextWatcher = new TextWatcher() {
        public void afterTextChanged(Editable editable) {           
        }

        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
        }

        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            suggestionNewText = s.toString();
            list = new ArrayList<Map<String, String>>();
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                     //data processing
                     list.add(data);
                     handler.sendEmptyMessage(1);
                            }
                        });

            Thread webAutoComplete = new Thread(new Runnable() {
                       @Override
                       public void run() {
                              //data process
                              list.add(data);
                              handler.sendEmptyMessage(1);
            }
            });

            try {
                     webAutoComplete.start();
                } catch (NullPointerException e) {
                } catch (IllegalStateException e) {
             }                      
        }
    };

And the handler for the adapter is next to the textwatcher.

    handler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 1: {

                ((Activity) CONTEXT).runOnUiThread(new Runnable() {
                    public void run() {
                        try {
                            if (list != null)

                            suggestionAdapter = new UrlSuggestionAdapter(
                                    CONTEXT,
                                    list,
                                    R.layout.two_line_autocomplete,
                                    new String[] { "title", "url" },
                                    new int[] { R.id.title, R.id.url
                                             });
                            if (list != null) {
                                refreshAdapter(list);
                                getUrl.setAdapter(suggestionAdapter);

                            }

                        } catch (Exception e) {

                        }
                    }
                });
                break;
            }
            case 2: {
                break;
            }
            }
        }
    };



public synchronized void refreshAdapter(List<Map<String, String>> items) {

    list = items;
    if (list != null) {

        suggestionAdapter.notifyDataSetChanged();
    }
}

The whole code above is inside Activity's OnCreate() method. I don't get the exception always. It happens on specific occasion. This issue is not yet resolved. I have added the notifydatasetchanged() method after the creation of adapter. Still that doesn't solve the problem. Can anyone point out what I am doing wrong here?

Answer 1

Fixed the error by adding

suggestionAdapter.notifyDataSetChanged();

on whenever the list is changed instead of calling it after a n number of insertions.