Java.lang.RuntimeException: Se ha producido un error al ejecutar doInBackground ()

A veces tengo este error de error en mi aplicación

java.lang.RuntimeException: An error occured while executing doInBackground() 

Este es el logCat completo:

 java.lang.RuntimeException: An error occured while executing doInBackground() at android.os.AsyncTask$3.done(AsyncTask.java:200) at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) at java.util.concurrent.FutureTask.setException(FutureTask.java:125) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) at java.lang.Thread.run(Thread.java:1019) Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() at android.os.Handler.<init>(Handler.java:121) at android.widget.Toast.<init>(Toast.java:68) at android.widget.Toast.makeText(Toast.java:231) at kostas.menu.olympiakos.nea.loadFeed(nea.java:84) at kostas.menu.olympiakos.nea.access$1(nea.java:75) at kostas.menu.olympiakos.nea$BackgroundAsyncTask_nea.doInBackground(nea.java:242) at kostas.menu.olympiakos.nea$BackgroundAsyncTask_nea.doInBackground(nea.java:1) at android.os.AsyncTask$2.call(AsyncTask.java:185) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) ... 4 more 

Y este es mi código de clase .nea:

 package kostas.menu.olympiakos; import java.io.IOException; import java.io.InputStream; import java.net.MalformedURLException; import java.net.URL; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import android.app.Dialog; import android.app.ListActivity; import android.app.ProgressDialog; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.net.Uri; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.Window; import android.view.animation.AlphaAnimation; import android.view.animation.Animation; import android.view.animation.AnimationSet; import android.view.animation.LayoutAnimationController; import android.view.animation.TranslateAnimation; import android.widget.Button; import android.widget.ImageView; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.SimpleAdapter; import android.widget.TextView; import android.widget.Toast; public class nea extends ListActivity{ private List<Message> messages; List<String> des = new ArrayList<String>();//to prosthesa gia na anoigei to keimeno sto alert List<String> text = new ArrayList<String>();//to prosthesa gia na anoigei o titlos sto alert List<URL> url = new ArrayList<URL>();//to prosthesa gia to koumpi pou pigainei sto link List<String> imgl = new ArrayList<String>();//to prosthesa gia na anoigei to keimeno sto alert @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.main2); if(isInternetOn()) { new BackgroundAsyncTask_nea().execute(); }else{ Toast.makeText(nea.this,R.string.no_connection, Toast.LENGTH_SHORT).show(); finish(); } } private void loadFeed(AsyncTask<Void, Void, Void> asyncTask){ try{ BaseFeedParser parser = new BaseFeedParser(); messages = parser.parse(); } catch (Throwable t){ Log.e("OSFP.News",t.getMessage(),t); Toast.makeText(nea.this, "Χρειάζεστε σύνδεση στο internet", Toast.LENGTH_SHORT).show(); finish(); } } private void displayRss(){ ArrayList<HashMap<String, String>> List_nea = new ArrayList<HashMap<String, String>>(messages.size()); for (Message msg : messages){ des.add(msg.getDescription());// keimeno text.add(msg.getTitle());// titlos url.add(msg.getLink());// link imgl.add(msg.getImgLink()); HashMap<String, String> map = new HashMap<String, String>(); map.put("name", msg.getTitle()); map.put("date", msg.getDate()); List_nea.add(map); ListAdapter mSchedule = new SimpleAdapter(this, List_nea, R.layout.row, new String[] {"name", "date"}, new int[] {R.id.TextView01, R.id.TextView02}); this.setListAdapter(mSchedule); } AnimationSet set = new AnimationSet(true); Animation animation = new AlphaAnimation(0.0f, 1.0f); animation.setDuration(400); set.addAnimation(animation); animation = new TranslateAnimation( Animation.RELATIVE_TO_SELF, 0.0f,Animation.RELATIVE_TO_SELF, 0.0f, Animation.RELATIVE_TO_SELF, -1.0f,Animation.RELATIVE_TO_SELF, 0.0f ); animation.setDuration(400); set.addAnimation(animation); LayoutAnimationController controller = new LayoutAnimationController(set, 0.5f); ListView listViewn = getListView(); listViewn.setLayoutAnimation(controller); } protected void onListItemClick(ListView l, View v, final int position, long id) { super.onListItemClick(l, v, position, id); Dialog dialog = new Dialog(this); String description = des.get(position).toString().replaceAll("\\<.*?>",""); String imagee=imgl.get(position).toString(); final URL link = url.get(position); dialog.requestWindowFeature(Window.FEATURE_NO_TITLE); dialog.setContentView(R.layout.single); dialog.setCancelable(true); Toast msg = Toast.makeText(nea.this, "The url is : "+imagee, Toast.LENGTH_LONG); msg.show(); //xrisimopoiisa toast gia na elegxw poio link pernw apo to site TextView title_dialog = (TextView) dialog.findViewById(R.id.title_dialog); title_dialog.setText(text.get(position)); TextView text = (TextView) dialog.findViewById(R.id.descr); text.setText(description); ImageView image1 = (ImageView) dialog.findViewById(R.id.image1); try { //where imageUrl is what you pulled out from the rss feed Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(imagee).getContent()); image1.setImageBitmap(bitmap); } catch (MalformedURLException e) { //log exception here } catch (IOException e) { //log exception here } Button btnt = (Button) dialog.findViewById(R.id.btnrss);//ti kanei to koumpi otan to patas gia to link btnt.setOnClickListener(new View.OnClickListener() { public void onClick (View view) { Intent viewMessage = new Intent(Intent.ACTION_VIEW, Uri.parse(link.toExternalForm())); startActivityForResult(viewMessage, 0); } }); dialog.show(); } //options menu @Override public boolean onCreateOptionsMenu(Menu menu2) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.menu2, menu2); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.refresh: new BackgroundAsyncTask_nea().execute(); break; } return true; } public class BackgroundAsyncTask_nea extends AsyncTask<Void, Void, Void> { private ProgressDialog dialog; int myProgress; @Override protected void onPostExecute(Void result) { displayRss(); dialog.dismiss(); } @Override protected void onPreExecute() { // TODO Auto-generated method stub dialog = ProgressDialog.show(nea.this, "", "Loading. Please wait...", true); myProgress = 0; } protected void onProgressUpdate(Integer... progress) { // TODO Auto-generated method stub //super.onProgressUpdate(values); dialog.setProgress(progress[0]); } @Override protected Void doInBackground(Void... arg0) { // TODO Auto-generated method stub loadFeed(this); return null; } } public final boolean isInternetOn() { ConnectivityManager connec = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE); // ARE WE CONNECTED TO THE NET if ( connec.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTED || connec.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTING || connec.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTING || connec.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTED ) { // MESSAGE TO SCREEN FOR TESTING (IF REQ) //Toast.makeText(this, connectionType + ” connected”, Toast.LENGTH_SHORT).show(); return true; } else if ( connec.getNetworkInfo(0).getState() == NetworkInfo.State.DISCONNECTED || connec.getNetworkInfo(1).getState() == NetworkInfo.State.DISCONNECTED ) { //System.out.println(“Not Connected”); return false; } return false; } } 

¿Por qué estoy recibiendo este error? ¿Cómo puedo resolverlo? Gracias 🙂

EDITAR:

 Public void toast_doInBck(View view) { // Do something long Runnable runnable = new Runnable() { @Override public void run() { for (int i = 0; i <= 10; i++) { Toast.makeText(nea.this,R.string.no_connection, Toast.LENGTH_SHORT).show(); handler.post(new Runnable() { @Override public void run() { } }); } } }; new Thread(runnable).start(); } 

EDIT2:

  private void loadFeed(AsyncTask<Void, Void, Void> asyncTask){ try{ BaseFeedParser parser = new BaseFeedParser(); messages = parser.parse(); } catch (Throwable t){ Log.e("OSFP.News",t.getMessage(),t); Looper.prepare(); Toast.makeText(nea.this, "Παρακαλώ προσπαθήστε αργότερα..", Toast.LENGTH_SHORT).show(); finish(); Looper.loop(); } } 

 catch (Throwable t){ Log.e("OSFP.News",t.getMessage(),t); Toast.makeText(nea.this, "Χρειάζεστε σύνδεση στο internet", Toast.LENGTH_SHORT).show(); finish(); }