CODEWITHSUNDEEP
androidandroid-asynctaskhttpclient
Jon Jon
Jon Jon

Reputation: 27

Passing a string from a AsyncTask to another activity

I'm trying to use the HTTPClient to get the html code of a website using an AsyncTask and passing back the code to my main Activity.

I used this code in order to (try to) do that :

public class AsyncTaskGet extends AsyncTask<String, String, String>{
    String result;
    InputStream in;

    protected String doInBackground(String... params) {

        try
        {
        HttpClient httpClient = new DefaultHttpClient();
        HttpGet httpRequest  = new HttpGet("http://www.google.fr");
        HttpResponse response = httpClient.execute(httpRequest);

        try{
            BufferedReader reader = new BufferedReader(new InputStreamReader(null, result), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }

            if (response != null) {
                in = response.getEntity().getContent(); 
            }
            in.close();
            result = sb.toString();
        }catch (Exception e) {
            Log.e("log_tag", "Error converting result " + e.toString());
        }
    }catch(IOException e){
        e.printStackTrace();
    }   
        return result;
    }   


       @Override
        protected void onPostExecute(String result) {
    //Here is one of my problem, I don't know how to get the returned value result as a string.           
        }    
}

This is my AsyncTaskGet, since I tried lots of fruitless attempts, I erased all my code in the main activity except this part.

new AsyncTaskGet().execute();

So basically, What i'd like to do is getting the result back on my main activity as a string to display it in a TextView. For now I want my app to be simple so I can understand the basics of using AsyncTasks, I didn't check for internet conectivity or stuff like that, I add the permission on the manifest to use internet (obviously

(Please be a little indulgent since it is one of my first apps)

One last thing, please excuse my poor english, i'm unfortunately not a native english speaker as you must have seen.

In advance, thanks a lot !

Sincerely :)

Upvotes: 0

Views: 1657

Answers (2)

WarrenFaith
WarrenFaith

Reputation: 57672

The easiest thing is to pass the calling activity via a constructor to your AsyncTask and create a method that will take the result as a parameter in the activity itself.

private Activity mActivity;

public AsyncTaskGet(Activity activity) {
    mActivity = activity;
}

protected void onPostExecute(String result) {
    mActivity.takeItBack(result);           
}

There are some limitations: the current code just works with a 1 to 1 relationship between AsyncTask and Activity, means the private member variable type must be the activity from which you call it. If you don't want that you need to implement an interface:

// interface
public interface AsyncTaskCallback {
    void takeItBack(String result);
}

// activity
public MyActivity implements AsyncTaskCallback {
    @Override
    public void takeItBack(String result) {
        // do something
    }
}

// AsyncTask
public class AsyncTaskGet extends AsyncTask<String, String, String> {
    private AsyncTaskCallback mCallback;

    public AsyncTaskGet(AsyncTaskCallback callback) {
        mCallback= callback;
    }

    protected void onPostExecute(String result) {
        mCallback.takeItBack(result);           
    }
}

Upvotes: 4

codeMagic
codeMagic

Reputation: 44571

You are already passing result to onPostExecute() as a String. If your AsyncTask is an inner class of your Activity then you can set result to a field variable in your Activity. Otherwise, you can call a function in your Activity from onPostExecute() to do what you want with the data.

Also, your poor English is really not bad at all :)

Upvotes: 2

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