Android runOnUiThread explanation

Question

I am trying to display a progress dialog during the onCreate   method of one of my activities  have the work done to populate the screen done in a thread  and then dismiss the progress dialog   Here is my onCreateMethod    dialog   new ProgressDialog HeadlineBoard this           dialog setMessage  Populating Headlines                 dialog show            populateTable      The populateTable method contains my thread and the code to dismiss the dialog  but for some reason  The activity comes up blank for about 10 secs doing the populateTable   work   and then I see the screen  I never see the dialog displayed  any ideas   Here is the populateTable   code     Adds a row to the table for each headline passed in private void populateTable         new Thread              Override         public void run                   If there are stories  add them to the table             for  Parcelable currentHeadline   allHeadlines                    addHeadlineToTable currentHeadline                                try                           code runs in a thread                      runOnUiThread new Runnable                                  Override                             public void run                                     dialog dismiss                                                                            catch  final Exception ex                       Log i  ---   Exception in thread                                  start

User · Answer

Instead of creating a thread  and using runOnUIThread  this is a perfect job for ASyncTask    In onPreExecute  create  amp  show the dialog  in doInBackground prepare the data  but don t touch the UI -- store each prepared datum in a field  then call publishProgress  In onProgressUpdate read the datum field  amp  make the appropriate change addition to the UI  In onPostExecute dismiss the dialog      If you have other reasons to want a thread  or are adding UI-touching logic to an existing thread  then do a similar technique to what I describe  to run on UI thread only for brief periods  using runOnUIThread for each UI step  In this case  you will store each datum in a local final variable  or in a field of your class   and then use it within a runOnUIThread block

User · Answer

This should work for you   public class MyActivity extends Activity        protected ProgressDialog mProgressDialog          Called when the activity is first created          Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main           populateTable               private void populateTable             mProgressDialog   ProgressDialog show this   Please wait   Long operation starts      true           new Thread                  Override             public void run                      doLongOperation                    try                           code runs in a thread                     runOnUiThread new Runnable                              Override                         public void run                                 mProgressDialog dismiss                                                                        catch  final Exception ex                        Log i  ---   Exception in thread                                              start                    fake operation for testing purpose        protected void doLongOperation             try               Thread sleep 10000             catch  InterruptedException e

User · Answer

If you already have the data  for  Parcelable currentHeadline   allHeadlines    then why are you doing that in a separate thread   You should poll the data in a separate thread  and when it s finished gathering it  then call your populateTables method on the UI thread   private void populateTable         runOnUiThread new Runnable            public void run                   If there are stories  add them to the table             for  Parcelable currentHeadline   allHeadlines                    addHeadlineToTable currentHeadline                             try                   dialog dismiss                  catch  final Exception ex                    Log i  ---   Exception in thread

[android] Android runOnUiThread explanation

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