Question

Now i am doing an android application.In that application I am using asynchtask class to parse json data and i have to set that values in to ui.My program is like this.

class Activity
{
textview tv;
oncreate()
{
    setcontentview(layout);
    tv=(textview)findviewbyid(id);
    call to pageload()
}
class PageLoad extends AsyncTask<String, Void, Boolean>
{
    doInBackground()
    {
        json parsing
        tv.setText(data);
    }
}
}

But I couldn’t set the value from pageload class.Please help me friends.

Answer 1

You need to understand that doInBackground() runs on a different thread to the UI, therefore you cannot access the UI here. AsyncTask has two other methods:

• onPreExecute() – before doInBackground() is run
• onPostExecute() – after doInBackground() is run, can receive the result of the work done by doInBackground()

You need to pass the result of doInBackground() to onPostExecute() where you can then set the TextView’s text.

I would suggest you read Google’s article on how to use the Asynctask which can be found at http://developer.android.com/resources/articles/painless-threading.html and look at the class AsyncTask.

Example Code

private class MyAsynctask extends AsyncTask<String, Void, String> {

     protected String doInBackground(String... urls) {
         //do something heavy or resource intensive
         String data = resultOfSomeWork();
         return data;
     }

     protected void onPostExecute(String result) {
         myTextView.setText(result);
     }
 }