I'm doing some background processing in my activity and have a ListView that shows the progress. I 'update' the listView with
adapter.notifyDataSetChanged();
However when I leave the activity and then come back, the background processes are still running, but the list view isn't updated. This is presumably because it's a new object, not the previous one. How do I maintain my list view object between activity loads?
This is my activity. I think the issue is that the 'adapter' variable that the download uses to bind to to show updates, is recreated in the onCreate method of the activity, and the 'adapter' variable that the download originally bound to is not in the activity anymore.
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.os.Bundle;
import android.os.Handler;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.model.ProgressEvent;
import com.amazonaws.services.s3.model.ProgressListener;
import com.amazonaws.services.s3.transfer.TransferManager;
//import com.amazonaws.auth.AWSCredentials;
//import com.amazonaws.auth.BasicAWSCredentials;
public class VideosActivity extends Activity {
ListView video_list;
CustomList adapter;
File storage_dir;
SharedPreferences completed_downloads; //http://developer.android.com/guide/topics/data/data-storage.html
SharedPreferences downloaded_data; //maps position to percent downloaded
SharedPreferences queue; //holds which fiiles are awaiting download
String images[]; //holds references to all thumnails for vids
String volume; //something like vol1 or vol2
String s3_dir; //the directory after the boucket that the files are stored in (do not add first slash)
String s3_bucket = "com--apps";
Handler handler = new Handler(); //'tunnel' through whci other threads communicate with main thread
Map<String, String[][]> video_config = new HashMap<String, String[][]>(); //holds info about video thumbs and filenames for all apps
ArrayList<String> arr_videos = new ArrayList<String>(); //holds video names
DownloadQueue queue_manager = new DownloadQueue();
@Override
public void onCreate(Bundle savedInstanceState) {
Log.v("dev", "onCreateCalled");
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
volume = getPackageName().split("\\.")[2]; //something like vol1 or vol2
s3_dir = "android/" + volume + "/"; //the directory after the boucket that the files are stored in (do not add first slash)
completed_downloads = getSharedPreferences("completed_downloads", 0);
downloaded_data = getSharedPreferences("downloaded_data", 0);
queue = getSharedPreferences("queue", 0);
storage_dir = getApplicationContext().getExternalFilesDir(null); //private to app, removed with uninstall
adapter = new CustomList(this, R.layout.customlist, arr_videos);
video_list = (ListView)findViewById(R.id.list);
video_list.setAdapter(adapter); //set adapter that specifies list contents
ensureStorageDirExists( storage_dir ); //make sure storage dir exists
set_video_data(); //store vid dat in array
ensure_connection_or_warn();
}
public boolean ensure_connection_or_warn()
{
if(have_connection())
{
return true;
}
else
{
Toast.makeText(this, "No Internet connection", Toast.LENGTH_LONG).show();
return false;
}
}
protected void ensureStorageDirExists( File dir )
{
if (!dir.exists())
{
dir.mkdirs();
}
}
public void set_video_data()
{
config_video_data(); //run config
images = video_config.get(getPackageName())[0]; //set images
for (String name : video_config.get(getPackageName())[1] ) { //set video info, this should be streamlined but is due to legacy code and my crap Java skills, consider doing like this: http://developer.android.com/guide/topics/resources/more-resources.html#TypedArray
arr_videos.add(name);
}
}
public SharedPreferences stored_vals()
{
return PreferenceManager.getDefaultSharedPreferences(this);
}
public boolean have_connection()
{
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
if(cm.getActiveNetworkInfo()!=null && cm.getActiveNetworkInfo().isConnected() && cm.getActiveNetworkInfo().isAvailable())
{
Log.v("dev", "have internet connection");
return true;
}
else
{
Log.v("dev", "No internet connection");
return false;
}
}
public class DownloadQueue
{
protected void process()
{
if (queue.size() > 0 && queue.get(0).download_status == "queued") //this is meant to force one download at a time
{
queue.get(0).start();
adapter.notifyDataSetChanged();
}
}
protected void add(Integer position)
{
queue.edit.putInt(position+"");
d.download_status = "queued";
adapter.notifyDataSetChanged();
}
protected boolean position_is_queued(Integer position)
{
for (Download d : queue ) {
if(d.position == position)
{
return true;
}
}
return false;
}
protected void remove(Download d)
{
queue.remove(d);
adapter.notifyDataSetChanged();
}
}
public class CustomList extends ArrayAdapter<String>
{
View view;
int position;
Button btn;
public CustomList(Context context, int layout_id, ArrayList<String> objects)
{
super(context, layout_id, objects);
}
@Override
public View getView(final int position, View convertView, ViewGroup view_group)
{
set_view(convertView);
this.position = position;
TextView text_view = (TextView) view.findViewById(R.id.name);
ImageView image = (ImageView) view.findViewById(R.id.img);
btn = (Button) view.findViewById(R.id.play);
prepare_btn();
text_view.setText( list_text() );
image.setImageResource(
getResources().getIdentifier(images[position], "drawable", getPackageName())
);
return view;
}
public String list_text()
{
String s = arr_videos.get( position ).replace("_", " ").replace(".m4v", "");
s = s.substring(2, s.length());
return s;
}
public void set_view(View convertView)
{
if(convertView == null)
{
LayoutInflater inflater = getLayoutInflater();
view = inflater.inflate(R.layout.customlist, null);
}
else
{
view = convertView;
}
}
public Boolean is_downloaded()
{
return completed_downloads.getBoolean(position + "", false);
}
public void prepare_btn()
{
btn.setTag((Integer) position);
if(is_downloaded() == true)
{
btn.setText("Play ");
btn.setEnabled(true);
btn.setOnClickListener( new OnClickListener()
{
public void onClick(View btn)
{
int position = (Integer) btn.getTag();
Intent i = new Intent(VideosActivity.this, PlayVideoActivity.class);
String video_path = storage_dir + "/" + arr_videos.get(position);
Log.v("video_path", video_path);
i.putExtra("video_path", video_path);
startActivity(i);
}
});
}
else if( downloaded_data.contains(position+"") ) //it it's currently being downloaded
{
btn.setText(downloaded_data.getInt(position+"", 0) + "%");
btn.setEnabled(false);
}
else if( queue_manager.position_is_queued(position) ) //it's in the queue
{
btn.setText("Queued");
btn.setEnabled(false);
}
else
{
btn.setText("Download");
btn.setEnabled(true);
btn.setOnClickListener( new OnClickListener()
{
public void onClick(View btn)
{
int position = (Integer) btn.getTag();
btn.setEnabled(false);
queue_manager.add(position);
}
});
}
}
}
public class Download
{
File new_video_file;
int position;
String download_status;
com.amazonaws.services.s3.transfer.Download download;
protected void queue(int position)
{
this.position = position;
queue_manager.add(this);
queue_manager.process();
//put this download in the queue
//start downloading if it's the only one in the queue
}
protected void start()
{
if(!ensure_connection_or_warn())
{
return;
}
this.download_status = "started";
this.new_video_file = new File(storage_dir, arr_videos.get(position)); //local file to be writtent to
TransferManager tx = new TransferManager(credentials);
//http://stackoverflow.com/questions/6976317/android-http-connection-exception
this.download = tx.download(s3_bucket, s3_dir + arr_videos.get(position), new_video_file);
download.addProgressListener(new ProgressListener()
{
public void progressChanged(final ProgressEvent pe)
{
handler.post( new Runnable()
{
@Override
public void run()
{
if ( pe.getEventCode() == ProgressEvent.COMPLETED_EVENT_CODE )
{
Download.this.onComplete();
}
else
{
Download.this.onProgressUpdate();
}
}
});
}
});
}
//protected void onProgressUpdate(Double progress)
protected void onProgressUpdate()
{
this.download_status = "downloading";
Double progress = this.download.getProgress().getPercentTransfered();
Integer percent = progress.intValue();
//Log.v("runnable", percent + "");
downloaded_data.edit().putInt(position+"", percent).commit();
adapter.notifyDataSetChanged();
}
protected void onComplete()
{
Log.v("dev", "download complete!!!");
//downloaded_data.remove(position);
this.download_status = "complete";
completed_downloads.edit().putBoolean(position + "", true).commit();
queue_manager.remove(this);
queue_manager.process();
adapter.notifyDataSetChanged();
// this.download.abort();
}
}
}
