Android ListView loading before data has been downloaded - have to restart view

Question

I am using a New Runnable httprequest data loading in one of my classes. I use that class to populate a ListView in one of my Activities, but the thing is that the views are loading before the data has been loaded.. I tried moving my initialize method, which initializes all views, but nothing happened. Every time I load the app, I have to reload the main view because there are no entries in the ListView. LoadReportList() is the method that makes an instance of the class holding the http request method.

 public class HomeActivity extends Activity {

private ArrayList<Report> reportList = null;

ListView listview;

private final boolean DEBUG = true;

private MyCustomArrayAdapter adapter = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);     
}

@Override
protected void onResume()
{
    super.onResume();
    loadReportList();
    initialize();
}

/**
 * This method initializes all the components needed for the activity
 */
private void initialize()
{
    /* Get a reference of the listview in our xml view */
    listview = (ListView) findViewById(R.id.reportsList);

    adapter = new MyCustomArrayAdapter(this, R.layout.single_listview_row);

    try{
        // Populate the list, through the adapter   
        for(final List_Item entry : getListEntries()) {
            adapter.add(entry);
            if(DEBUG)Log.i("HomeActivity","in adding List_Item entries to the adapter");
        }
    }catch(Exception e){
        Log.i("In initialize() HomeActivity","Could not load the list with entries");

        loadReportList();
    }

    listview.setAdapter(adapter);

    listview.setOnItemClickListener(new OnItemClickListener(){  
        public void onItemClick(AdapterView<?> arg0, View arg1, int position, long id) {

            /* Class to assist us in loading the activity */
            Class editClass = null;
            try {
                editClass = Class.forName(".DetailsActivity");
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            /* create bundle to pass the ID of the deck that was clicked */
            Bundle reportPassed = new Bundle();
            //reportPassed.putInt("Report", reportList.get(4).getId());
            reportPassed.putSerializable("report", reportList.get(position));

            /* Start the new intent and also pass a bundle that will contain the name of the card that was clicked */
            Intent ourIntent = new Intent(HomeActivity.this, editClass);
            ourIntent.putExtras(reportPassed);//passing the bundle to the activity
            //start the activity
            startActivity(ourIntent);
        }
    });
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.home, menu);
    return true;
}

/* Create the list of objects of type List_Item, in our case it will be Decks */
private List<List_Item> getListEntries(){

    /* Create an ArrayList of List_Items */
    final ArrayList<List_Item> entries = new ArrayList<List_Item>();

    if(reportList == null || reportList.isEmpty())
        loadReportList();

    /* Create the rows for the ListView by adding them into the ArrayList "entries".
     * reportList is a global ArrayList<Report> that we populate by a method call to the class JsonParser.
     * Look above.
     * */
    for(int i = 0; i < reportList.size(); i++) {
        if(DEBUG)Log.i("getListEntries HomeActivity","Passing through reportlistEntries");
        entries.add(
                new List_Item(((Report)reportList.get(i)).getType(), Integer.toString(((Report)reportList.get(i)).getId()), ((Report)reportList.get(i)).getId())
                );
    }
    return entries;
}

//This method loads the reportList arraylist with all Report objects
void loadReportList(){
    try {
        reportList = new JsonParser().getArrayList();
    } catch (UnsupportedEncodingException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IllegalStateException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (JSONException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
}

}

Here is my HTTP request:

//The constructor simply calls the getHttpResponse()
    public JsonParser() throws UnsupportedEncodingException, IllegalStateException,  IOException, JSONException
{
    getHttpResponse();
}
/*
 *  This method returns an HttpResponse
 */
public void getHttpResponse(){
    Log.i("getHttpResponse", "Right after declaring HttpResponse response");      
    new Thread(new Runnable() {
        public void run() {
            runRequest();
        }
      }).start();
}

void runRequest()
{
    HttpResponse response = null;
    HttpClient client = new DefaultHttpClient();
    HttpGet request = new HttpGet();
    try {
        request.setURI(new URI("http://....../report_data.json"));
        response = client.execute(request);
    } catch (URISyntaxException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    if(response!= null)
        Log.i(response.toString(), "testing response.toString()");

    //call to populate the list
    try {
        populateList(response);
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

score 2 · Accepted Answer · edited May 23 '17 at 12:12

Instead of using a java thread you can take advantage of the AsyncTask class of the Android SDK. You can show a progress dialog onPreExecute method, do all the heavy work(in your case the http stuff) in the doInBackground method and populate your list and dismiss the progress dialog in the onPostExecute method. You can create an inner class e.g Task which extends the AsyncTask method and call it from onCreate or onResume ,whatever suits you, like this.

new Task().execute();

AsyncTask has given the name"Painless threading" because it is there to make our life easier. It is consider good practice to reuse already implemented code which is intended for such tasks.

You can find many threads regarding AsyncTasks use in StackOverflow e.g progressDialog in AsyncTask

Just used that thread and I fixed my code!! Thanks buddy. I appreciate the help. — Georgi Angelov, Apr 28 '13 at 21:39

score 0 · Answer 2 · answered Apr 28 '13 at 21:27

So what you need to do is call initialize() after your runRequest code completes.

I agree with the above poster that an AsyncTask will make this easy. Get rid of the threading code in your JsonParser class. AsyncTask will take care of that for you.

Here's a snippet.

new AsyncTask<Void, Void, Void>() {
    @Override
    protected Void doInBackground(Void... voids) {
        myparser = new JSONParser();
        myparser.runRequest()
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        initialize();
    }
}.execute();

Android ListView loading before data has been downloaded - have to restart view

2 Answers2