Question

I have a program that search some elements and show these on a GoogleMap.
I want to show a progress dialog before the end of all procedures that set the various geopoint on the map.

Searching I have found this code to show the progress dialog before the end of a method.

    ProgressDialog dialog; 
private class Test extends AsyncTask<Void, Void, Void> { 

    @Override 
    protected void onPreExecute() { 
        dialog = new ProgressDialog(Main.this); 
        dialog.setMessage("Loading...."); 
        dialog.setIndeterminate(true); 
        dialog.setCancelable(true); 
        dialog.show(); 
    } 

    @Override 
    protected Void doInBackground(Void... voids) { 
        try { 
            runOnUiThread(new Runnable() { 
                public void run() { 

                } 
            }); 
            //your code 

    } 

    @Override 
    protected void onPostExecute(Void params) { 
        dialog.dismiss(); 
        //result 

    } 
} 

The class where I must add the async task is something like this:

public class FindItOnMap extends MapActivity{
static String[] foundResults;

@Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.ricerca_condominio);
         mapView = (MapView)findViewById(R.id.mapView);

         mapController = mapView.getController();

         mapView.setClickable(true);

         mapView.setBuiltInZoomControls(true);

         mapController.setZoom(12);

         myLocationOverlay = new MyLocationOverlay(this, mapView);
         List<Overlay> overlays = mapView.getOverlays();
         overlays.add(myLocationOverlay);
         myLocationOverlay.enableMyLocation();
                 ...........



         ((ImageButton) findViewById(R.id.btSearch)).setOnClickListener(mSearchListenerListener);


}


        OnClickListener mSearchListener = new OnClickListener() {
            public void onClick(View v) {
                    String Location=editorLocation.getText().toString();
                    String name=editorName.getText().toString();
                //static method that updates the lists foundResult
                search(name, location);
                //static method that use the static array foundResult to update the map
                updateMapWithResult();

            }
     };

The methods that requires time before return the solution are invoked when I click on a button

search(name, location);

updateMapWithResult();

The problem is that my class extends yet MapActivity and I cannot use multiple inheritance to extend another class.
How could I do to solve the problem?

Answer 1

If you don’t want to use multiple inheritance, you can define your AsyncTask as an inner class and use an instantiated object of the AsycTask you defined to do your job. Something like this:

public class FindItOnMap extends MapActivity {

static String[] foundResults;
private ProgressDialog dialog;

 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.ricerca_condominio);
     mapView = (MapView)findViewById(R.id.mapView);

     mapController = mapView.getController();

     mapView.setClickable(true);

     mapView.setBuiltInZoomControls(true);

     mapController.setZoom(12);

     myLocationOverlay = new MyLocationOverlay(this, mapView);
     List<Overlay> overlays = mapView.getOverlays();
     overlays.add(myLocationOverlay);
     myLocationOverlay.enableMyLocation();
             ...........



     ((ImageButton) findViewById(R.id.btSearch)).setOnClickListener(mSearchListenerListener);


     }

    OnClickListener mSearchListener = new OnClickListener() {
        public void onClick(View v) {
                String Location=editorLocation.getText().toString();
                String name=editorName.getText().toString();
             //Call the AsyncTask here
            new YourCustomAsyncTask().execute(new String[] {name, location});

        }


    private class YourCustomAsyncTask extends AsyncTask <String, Void, Void> { 

        @Override 
        protected void onPreExecute() { 
           dialog = new ProgressDialog(Main.this); 
           dialog.setMessage("Loading...."); 
           dialog.setIndeterminate(true); 
           dialog.setCancelable(true); 
           dialog.show(); //Maybe you should call it in ruinOnUIThread in doInBackGround as suggested from a previous answer
        } 

        @Override 
        protected Void doInBackground(String... strings) { 
           try { 

              search(strings[0], string[1]);

              runOnUiThread(new Runnable() { 
                 public void run() { 
                    updateMapWithResult(); //Or call it onPostExecute before progressDialog's dismiss. I believe this method updates the UI so it should run on UI thread
                 } 
               }); 

           } catch(Exception e) {
           }

        }

    @Override 
    protected void onPostExecute(Void params) { 
        dialog.dismiss(); 
        //result 

    } 


.....
}