CODEWITHSUNDEEP
androidandroid-asynctaskandroid-alertdialog
Harsha M V
Harsha M V

Reputation: 54949

Alert Dialog and ASync Task

i am trying to use Alert Dialog Box and Async Task in the activity and am getting the following error

Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

Code:

public class loginTask extends AsyncTask<Void, Void, Void> {
    public ProgressDialog loginDialog = new ProgressDialog(
            LoginActivity.this);

    @Override
    protected void onPreExecute() {
        loginDialog.setMessage("Please wait Logging in");
        loginDialog.show();
    }

    @Override
    protected Void doInBackground(Void... params) {

        if(loginUser()) {
            loginDialog.dismiss();
            alertbox("title", "winnn", "Okay");
        } else {
            loginDialog.dismiss();
            alertbox("title", "message", "Okay");
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void unused) {
        loginDialog.dismiss();
        Intent intentHome = new Intent(LoginActivity.this,
                HomeActivity.class);
        startActivity(intentHome);
    }
}

Upvotes: 1

Views: 5519

Answers (2)

Paresh Mayani
Paresh Mayani

Reputation: 128428

You can't update UI inside the doInBackground() method directly. (Yes if you still want to execute then write the same inside the runOnUiThread() method inside the doInBackground())

Otherwise, do it inside the onPostExecute() method.

public class loginTask extends AsyncTask<Void, Void, Void> 
{
    public ProgressDialog loginDialog = new ProgressDialog( LoginActivity.this );
    public Boolean flag;

    @Override
    protected void onPreExecute() {
        loginDialog.setMessage("Please wait Logging in");
        loginDialog.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
        if(loginUser())
          flag = true;
        else 
          flag=false;

        return null;
    }

    @Override
    protected void onPostExecute(Void unused) {
        loginDialog.dismiss();

        if(flag)
          alertbox("title", "winnn", "Okay");
        else
          alertbox("title", "message", "Okay");
    }
}

Upvotes: 10

medampudi
medampudi

Reputation: 399

the onPreexecute and onPostExecute are part of the UI parts in the Async Task.. the doInBackground is a seperate thread so any thing done inside the doInBackground needs to be handled in the form of progressUpdate 

 private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
     protected Long doInBackground(URL... urls) {
         int count = urls.length;
         long totalSize = 0;
         for (int i = 0; i < count; i++) {
             totalSize += Downloader.downloadFile(urls[i]);
             publishProgress((int) ((i / (float) count) * 100));
         }
         return totalSize;
     }

     protected void onProgressUpdate(Integer... progress) {
         setProgressPercent(progress[0]);
     }

     protected void onPostExecute(Long result) {
         showDialog("Downloaded " + result + " bytes");
     }
 }

Example Reference: Link

reflects any changes you need to make to the UI inbetween the doInBackground process.

Upvotes: 1

Related Questions