Question

ProgressDialog quits updating when orientation of screen changes. I have put into place a fix that salvages the asynctask and sets the activity of the asynctask to the new activity after it is destroyed and rebuilt. The percentage complete on the progressdialog stays at the percentage it was at before the orientation change.

What am I missing?

package net.daleroy.fungifieldguide.activities;

import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Toast;
import net.daleroy.fungifieldguide.R;
import net.daleroy.fungifieldguide.fungifieldguideapplication;

public class FungiFieldGuide extends Activity {
    //static final int PROGRESS_DIALOG = 0;
    //ProgressThread progressThread;
    private final static String LOG_TAG = FungiFieldGuide.class.getSimpleName(); 
    fungifieldguideapplication appState;
    private DownloadFile mTask;
    public boolean mShownDialog;
    ProgressDialog progressDialog;
    private final static int DIALOG_ID = 1; 

    @Override
    protected void onPrepareDialog(int id, Dialog dialog) {
        super.onPrepareDialog(id, dialog);

        if ( id == DIALOG_ID ) {
            mShownDialog = true;
        }
    }

    private void onTaskCompleted() {
        Log.i(LOG_TAG, "Activity " + this + " has been notified the task is complete.");

        //Check added because dismissDialog throws an exception if the current
        //activity hasn't shown it. This Happens if task finishes early enough
        //before an orientation change that the dialog is already gone when
        //the previous activity bundles up the dialogs to reshow.
        if ( mShownDialog ) {
            dismissDialog(DIALOG_ID);
            Toast.makeText(this, "Finished..", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    protected Dialog onCreateDialog(int id) {
        switch(id) {
        case DIALOG_ID:
            progressDialog = new ProgressDialog(this);
            progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            progressDialog.setMessage("Loading Database (only first run)...");
            return progressDialog;
        default:
            return super.onCreateDialog(id);
        }
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);
        appState = ((fungifieldguideapplication)this.getApplication());

        Object retained = getLastNonConfigurationInstance();
        if ( retained instanceof DownloadFile ) {
            Log.i(LOG_TAG, "Reclaiming previous background task.");
            mTask = (DownloadFile) retained;
            mTask.setActivity(this);
            //showDialog(DIALOG_ID);
        } 
        else {
            if(!appState.service.createDataBase())
            {
                Log.i(LOG_TAG, "Creating new background task.");
                //showDialog(DIALOG_ID);
                mTask = new DownloadFile(this);
                mTask.execute("http://www.codemarshall.com/Home/Download");
            }
        }
            //showDialog(PROGRESS_DIALOG);

        View btn_Catalog = findViewById(R.id.btn_Catalog);
        btn_Catalog.setOnClickListener(new OnClickListener() 
        {
            public void onClick(View v) 
            {   
                Intent i = new Intent(getBaseContext(), Cat_Genus.class);//new Intent(this, Total.class);
                startActivity(i);
            }
        });

        View btn_Search = findViewById(R.id.btn_Search);
        btn_Search.setOnClickListener(new OnClickListener() 
        {
            public void onClick(View v) 
            {   
                Intent i = new Intent(getBaseContext(), Search.class);//new Intent(this, Total.class);
                startActivity(i);
            }
        });
    }

    @Override
    public Object onRetainNonConfigurationInstance() {
            mTask.setActivity(null);
            return mTask;
    } 

    @Override
    public void onDestroy()
    {
        super.onDestroy();
        //progressDialog.dismiss();
        //progressDialog = null;
        appState.service.ClearSearchParameters();
    }

    private class DownloadFile extends AsyncTask<String, Integer, Boolean>{
        private FungiFieldGuide activity;
        private boolean completed;
        private String Error = null;
        private String Content;

        private DownloadFile(FungiFieldGuide activity) {
            this.activity = activity;
        }

        @Override
        protected void onPreExecute()
        {
            showDialog(DIALOG_ID);
        }


        @Override
        protected Boolean doInBackground(String... urlarg) {
            int count;

            try {
                URL url = new URL(urlarg[0]);
                URLConnection conexion = url.openConnection();
                conexion.setDoInput(true);
                conexion.setUseCaches(false);

                // this will be useful so that you can show a tipical 0-100% progress bar
                int lenghtOfFile = conexion.getContentLength();

                // downlod the file
                InputStream input = new BufferedInputStream(conexion.getInputStream());
                OutputStream output = new FileOutputStream("/data/data/net.daleroy.fungifieldguide/databases/Mushrooms.db");

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    publishProgress((int)total*100/lenghtOfFile);
                    output.write(data, 0, count);
                }

                output.flush();
                output.close();
                input.close();
            } catch (Exception e) {
                Log.i(LOG_TAG, e.getMessage());
            }
            return null;
        }

        @Override
        public void onProgressUpdate(Integer... args){
            progressDialog.setProgress(args[0]);
        }

        @Override
        protected void onPostExecute(Boolean result)
        {
            completed = true;
            notifyActivityTaskCompleted();
        }

        private void notifyActivityTaskCompleted() {
            if ( null != activity ) {
                activity.onTaskCompleted();
            }
        }

        private void setActivity(FungiFieldGuide activity) {
            this.activity = activity;
            if ( completed ) {
                    notifyActivityTaskCompleted();
            }
        }
    }
}

Answer 1

This is not a real solution but to prevent this I just disabled orientation changes during the life of the AsyncTask with adding first:

setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);

and when the job is done:

setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);

Hope this helps.