CODEWITHSUNDEEP
androidjsonandroid-asynctask
Shweta
Shweta

Reputation: 807

Unable to call arraylist in another activity using AsyncTask- Android app

I have an application where I have a separate class named "Images1" which extends AsyncTask, where in I am fetching all the gallery URL via JSON.I am instantiating the AsyncTask class in another activity where I need the arraylist returned by the "Images1" class.However I am unable to get the arraylist. Please suggest what steps should be taken.Thanks in advance 

public   class Images1 extends AsyncTask<Void, Void,  ArrayList<String>> {
    ProgressDialog mPreogressDialog;
    private static String url = "http://www.tts.com/album_pro/array_to_encode";
     JSONParser jParser = new JSONParser();
     ArrayList<String> image_urls = new ArrayList<String>();
    @Override
    protected void onPreExecute() {

     mPreogressDialog = ProgressDialog.show(Images1.this, "", "Uploading Document. Please wait...", true);
    }

    @Override
    protected  ArrayList<String> doInBackground(Void... params) {
        // TODO Auto-generated method stub
        //Do your stuff here call ur methods
                    imagedownload();
        return image_urls;
    }

    protected void onPostExecute(ArrayList<String> result) {
        super.onPostExecute(result);
        // TODO Auto-generated method stub
        if (mPreogressDialog.isShowing())
            mPreogressDialog.dismiss();


    }



public void imagedownload(){


JSONObject json = jParser.getJSONFromUrl(url);

                try{
            JSONObject seo = json.getJSONObject("SEO");
            JSONArray folio = seo.getJSONArray("Folio");

            JSONArray image_urls1 = new JSONArray();
            String s1=seo.getString("Folio");

                            for(int i=0;i<folio.length();++i)
                            {
                        String m = folio.getString(i);
                        Log.v("M"+i,m);
                        image_urls.add(m+ ",");

                            }
                }
                catch(Exception e)
                {
                    e.printStackTrace();
                }
}
}

In the another activity I am instantiating the class and calling it as 

Images1 img1;
new img1.execute();

Upvotes: 0

Views: 495

Answers (4)

Sergey Zhabinskii
Sergey Zhabinskii

Reputation: 488

Another option is to extend this AsyncTask. Call following piece of code in your activity:

new Images1() {
    protected void onPostExecute(ArrayList<String> result) {
        super.onPostExecute(result);
        //here you process received result
    }
}.execute();

Upvotes: 0

Amandeep singh
Amandeep singh

Reputation: 1883

I will suggest you one thing just take new Arraylist and make a for loop and add all the values of the image_urls in that list on the onPostExecute Method of AsyncTask class and call that arraytlist.

Upvotes: 1

ρяσѕρєя K
ρяσѕρєя K

Reputation: 132982

I am unable to get the arraylist.

to get result back in Activity where u are starting AsyncTask u will need to execute AsyncTask as :

ArrayList<String> image_urls=new Images1.execute(params_).get();

but this will block UI Thread execution until AsyncTask doInBackground method execution complete. use Thread to execute AsyncTask if u are using AsyncTask.get() method to avoid UI freezing

Second way is pass Activity Context to Images1 class using class constructor and do your work inside onPostExecute. for example :

public   class Images1 extends AsyncTask<Void, Void,  ArrayList<String>> {
 //...your code here..

Context context;

public Images1(Context context){
  this.context=context;
}
////....your code here....

 protected void onPostExecute(ArrayList<String> result) {
        super.onPostExecute(result);
        // TODO Auto-generated method stub

          // do your work here...
    }
}

use context for accessing or updating UI from onPostExecute

Upvotes: 2

Sergey Zhabinskii
Sergey Zhabinskii

Reputation: 488

You can use Messages and Handlers here. Take a look at this article: http://mobileorchard.com/android-app-developmentthreading-part-1-handlers/. You can send a message from another thread, containing ArrayList. And then handle this message in handleMessage() function of your activity.

Upvotes: 1

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