Question

In my application I use JSON webservice to get data from Google Navigation api. I use the code is below.
I got the following exception

android.os.NetworkOnMainThreadException.

How to use AsyncTask? here is my code. Thanks.`public class MainActivity extends MapActivity {

  MapView mapView ;

public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    System.out.println("*************1**************1");
    setContentView(R.layout.activity_main);
    System.out.println("*************2**************");
    mapView = (MapView) findViewById(R.id.mapv); 
    System.out.println("*************3**************");



                Route route = directions(new GeoPoint((int)(26.2*1E6),(int)(50.6*1E6)), new GeoPoint((int)(26.3*1E6),(int)(50.7*1E6)));

              RouteOverlay routeOverlay = new RouteOverlay(route, Color.BLUE);
              mapView.getOverlays().add(routeOverlay);
            mapView.invalidate();


    System.out.println("*************4**************");

}



@SuppressLint("ParserError")
private Route directions(final GeoPoint start, final GeoPoint dest) {



    //https://developers.google.com/maps/documentation/directions/#JSON <- get api
    String jsonURL = "http://maps.googleapis.com/maps/api/directions/json?";
    final StringBuffer sBuf = new StringBuffer(jsonURL);
    sBuf.append("origin=");
    sBuf.append(start.getLatitudeE6()/1E6);
    sBuf.append(',');
    sBuf.append(start.getLongitudeE6()/1E6);
    sBuf.append("&destination=");
    sBuf.append(dest.getLatitudeE6()/1E6);
    sBuf.append(',');
    sBuf.append(dest.getLongitudeE6()/1E6);
    sBuf.append("&sensor=true&mode=driving");

    Parser parser = new GoogleParser(sBuf.toString());
      Route   r =  parser.parse();
   System.out.println("********r in thread*****" +r);                  
            return r;
}



@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}
@Override
protected boolean isRouteDisplayed() {
    // TODO Auto-generated method stub
    return false;
}

}
`

Answer 1

@imran khan idea of using another thread is the right one. From HoneyComb and above, you can’t do any networking operation inside the UI Thread. The UI Thread is the thread responsible for displaying views and receiving touch events and it must be free for this, not blocked by a long running operation. (Otherwise you got an ANR on Android).

But it’s actually not a very good idea to use an AsyncTask for long running operations like a network Request. The AsyncTask javadocs even states they have been designed for short runnning operations…

The best approach is to use a service for that. I encourage you to read this infographics from the RoboSpice library and use RoboSpice, it will ease creating a service with networking and will make it easier for your to parse your json content using Spring Android.