Question

I am building song list application. I want to display splash screen while loading data. For that use I set an AsyncTask combined with ViewSwitcher to switch xml layout beetween splash screen (just logo and circle progressbar) and main screen. The problem is when it comes to puting data in ListView, I am using BaseAdapter which is in separate class, and it throws error "The Constructor LazyAdapter(Home.LoadViewTask, ArrayList<HashMap<String,String>>) is undefined".

This is source of Home Class which has AsyncTask:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.main);

    mBtnNaslovnica = (Button) findViewById(R.id.mBtnNaslovnica);
    mBtnNaslovnica.setSelected(true);

    new LoadViewTask().execute();
}

//To use the AsyncTask, it must be subclassed
public class LoadViewTask extends AsyncTask<Void, Integer, Void>
{
    //A TextView object and a ProgressBar object
    private TextView tv_progress;
    private ProgressBar pb_progressBar;

    //Before running code in the separate thread
    @Override
    protected void onPreExecute() 
    {
        //Initialize the ViewSwitcher object
        viewSwitcher = new ViewSwitcher(Home.this);
        /* Initialize the loading screen with data from the 'loadingscreen.xml' layout xml file. 
         * Add the initialized View to the viewSwitcher.*/
        viewSwitcher.addView(ViewSwitcher.inflate(Home.this, R.layout.init, null));

        //Set ViewSwitcher instance as the current View.
        setContentView(viewSwitcher);
    }

    //The code to be executed in a background thread.
    @Override
    protected Void doInBackground(Void... params) 
    {
        ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL); // getting XML from URL
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_SONG);
        // looping through all song nodes <song>
        for (int i = 0; i < nl.getLength(); i++) {
            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);
            // adding each child node to HashMap key => value
            map.put(KEY_ID, parser.getValue(e, KEY_ID));
            map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
            map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST));
            map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION));
            map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL));

            // adding HashList to ArrayList
            songsList.add(map);
        }

        list=(ListView)findViewById(R.id.list);

        // Getting adapter by passing xml data ArrayList
        adapter=new LazyAdapter(this, songsList);        
        list.setAdapter(adapter);
        // Click event for single list row
        list.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {    

            }
        });

        return null;
    }

    //After executing the code in the thread
    @Override
    protected void onPostExecute(Void result) 
    {
        /* Initialize the application's main interface from the 'main.xml' layout xml file. 
         * Add the initialized View to the viewSwitcher.*/
        viewSwitcher.addView(ViewSwitcher.inflate(Home.this, R.layout.main, null));
        //Switch the Views
        viewSwitcher.showNext();
    }
}

//Override the default back key behavior
@Override
public void onBackPressed() 
{
    //Emulate the progressDialog.setCancelable(false) behavior
    //If the first view is being shown
    if(viewSwitcher.getDisplayedChild() == 0)
    {
        //Do nothing
        return;
    }
    else
    {
        //Finishes the current Activity
        super.onBackPressed();
    }
}

And this is the source of LazyAdapter class:

private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader; 

public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
    activity = a;
    data=d;
    inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    imageLoader=new ImageLoader(activity.getApplicationContext());
}

public int getCount() {
    return data.size();
}

public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return position;
}

public View getView(int position, View convertView, ViewGroup parent) {
    View vi=convertView;
    if(convertView==null)
        vi = inflater.inflate(R.layout.list_row, null);

    TextView title = (TextView)vi.findViewById(R.id.title); // title
    TextView artist = (TextView)vi.findViewById(R.id.artist); // artist name
    TextView duration = (TextView)vi.findViewById(R.id.duration); // duration
    ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); // thumb image

    HashMap<String, String> song = new HashMap<String, String>();
    song = data.get(position);

    // Setting all values in listview
    title.setText(song.get(Home.KEY_TITLE));
    artist.setText(song.get(Home.KEY_ARTIST));
    duration.setText(song.get(Home.KEY_DURATION));
    imageLoader.DisplayImage(song.get(Home.KEY_THUMB_URL), thumb_image);
    return vi;
}

`

Answer 1

You cannot do any UI modification.. such as setting a label text, modifying list inside a AsyncTask.doInBackground.. because it is a separate thread…

  list=(ListView)findViewById(R.id.list);


    // Getting adapter by passing xml data ArrayList
    adapter=new LazyAdapter(this, songsList);        
    list.setAdapter(adapter);
    // Click event for single list row
    list.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {


        }
    });

you should put that part of the code before you call

new LoadViewTask().execute();

and inside the doInBackground()… as the last line..
put this line..
adapter.notifyDataSetChanged();