How can I set the text for a textview from an AsyncTask activity?

Question

I have got a Fragment Activity that contains a textview and another class that extends AsyncTask. Now I would like to use the onPostExecute(String result) method to set the result text in my textview that is in my fragment activity.

How can I do that? I already created a custom constructor for the AsyncTask class that takes in a context object. How can I use that??

This is how I create a task object in my Fragment activity:

String query = "someText";
Task task = new Task(this.getActivity());
task.execute(query);

This is a snippet from my task class:

public class Task extends AsyncTask<String, Void, String> {

    private Context context;

    public Task (Context context) {
        this.context = context;
    }

    protected void onPostExecute(String result) {
    super.onPostExecute(result);
    // ??? What comes here ???
    }
}

is your asynctask an inner class of your activity class. asynctask is not a activity — Raghunandan, Aug 14 '13 at 14:44
@user2426316 please tell, is super neccessary to be called here? if so, what does it do? (off topic) — Zeeshan, Aug 14 '13 at 15:07

score 5 · Accepted Answer · edited Sep 12 '15 at 20:26

5

TextView txt = (TextView)((Activity)context).findViewById(R.id.watheveryouwant);
txt.setText("blabla");

But you should pass an Activity and not a Context, will be easier ;-)

Or

    public Task (Context context, TextView t) {
        this.context = context;
        this.t = t;
    }
   super.onPostExecute(result);
        t.setText("BlahBlah")
    }

Should do the trick

edited Sep 12 '15 at 20:26

DarckBlezzer

4,578
1
41
51

answered Aug 14 '13 at 14:48

Waza_Be

39,407
49
186
260

In this example you're setting the text on a non-ui-thread. This might lead to problems? – Mirco Widmer Aug 14 '13 at 14:56
1

http://developer.android.com/reference/android/os/AsyncTask.html : onPostExecute(Result), invoked on the UI thread after the background computation finishes. – Waza_Be Aug 14 '13 at 14:57
the second solution with the constructor did the trick for me! Thanks! – user2426316 Aug 14 '13 at 15:19

score 0 · Answer 2 · edited May 23 '17 at 11:58

I picked the solution from

How do I return a boolean from AsyncTask?

new Task(getActivity()).execute(query);

In the Constructor of AsyncTask

TheInterface listener;
public Task(Context context)
{
  listener = (TheInterface) context; 
}

Interface

public interface TheInterface {

public void theMethod(String result); // your result type

 }

Then

In your doInbackground return the result.

In your onPostExecute

if (listener != null) 
{
  listener.theMethod(result); // result is the String
  // result returned in doInbackground 
  // result of doInbackground computation is a parameter to onPostExecute 
}

In your activity class or fragment implement the interface

public class ActivityName implements Task.TheInterface

Then

@Override
 public void theMethodString result) { 
    tv.setText(result); 
    // set the text to textview here with the result of background computation
    // remember to declare textview as a class member.
 }

Edit:

You are also missing @Override annotation for your onPostExecute

score 0 · Answer 3 · answered Aug 14 '13 at 14:53

0

You can pass to the AsynkTast the instance of the TextView as a parameter, and call setText in onPostExecute.

answered Aug 14 '13 at 14:53

alfdev

1,039
1
10
23

score 0 · Answer 4 · answered Aug 14 '13 at 15:04

0

in your case, simply following will come here:

((TextView)findViewById(R.id.xyz)).setText("abc");

answered Aug 14 '13 at 15:04

Zeeshan

2,884
3
28
47

How can I set the text for a textview from an AsyncTask activity?

4 Answers4

Linked