CODEWITHSUNDEEP
androidautocompletetextview
Andrei Suvorov
Andrei Suvorov

Reputation: 531

Android AutocompleteTextView Adapter for asynchronous API with callbacks

I working on implementation of autocomplete suggestion via some REST API (it's actually Nokia Here Geocoder Autocomplete API, but its not so important). I write custom adapter for AutoCompleteTextView. 

public class GeoAutocompleteAdapter extends BaseAdapter implements Filterable {

@Override
public Filter getFilter() {
    Filter filter = new Filter() {

        @Override
        protected Filter.FilterResults performFiltering(CharSequence constraint) {
            FilterResults filterResults = new FilterResults();

            // obtain some autocomplete data

            filterResults.values = res;
            filterResults.count = res.size();
            return filterResults;
        }
        //...
      }
//...
}

As far as I understand, section "obtain some autocomplete data" run in thread pool. If I obtain results for autocomplete in synchronous way - its working. For example, I can use HttpURLConnection and InputStream - all synchronous blocking call works pretty well here.

But what if I need to call some API here, which operate in asynchronous way, like via Callback \ Listener?

How can I call something like this inside performFiltering ?

request.execute(
        new ResultListener<List<com.here.android.mpa.search.Location>>() {
            @Override
            public void onCompleted(List<Location> locations, ErrorCode errorCode) {

            }
        //...
        }

How can I postpone returning from methods while callback not give me an results?

Thanks in advance,

Upvotes: 4

Views: 1206

Answers (1)

Arnav Rao
Arnav Rao

Reputation: 7002

You can make the thread to wait for results from async API in performFiltering method till response is received.

Since method performFiltering runs in a worker thread, you can make the thread wait for results as shown below, lockTwo is object and placeResults boolean indicator.

        while (!placeResults) {
            synchronized (lockTwo) {
                try {
                    lockTwo.wait();
                } catch (InterruptedException e) {

                }
            }
        }

In the callback or listener, once response is processed, add notify as shown below.

                placeResults = true;
                synchronized (lockTwo) {
                    lockTwo.notifyAll();
                }

For more information you can check places auto search example at http://www.zoftino.com/google-places-auto-complete-android

Upvotes: 6

Related Questions