Develop Reference

Android: Main Thread blocked despite using AsyncTask

I have a Activity that contains over 100 complex views (with images, text views etc). Showing up these views is to hard to do it without a Thread that loads the views asynchronously. So I tried to do it with an AsyncTask. I am not sure whether this is the correct way because the "hard staff" is something that HAS to be done in the UI Thread.
Now I've got the problem that the UI freezes though I used the onProgressUpdate for adding the views in the to parent view. I thought that this would result in single loading views that appear successive in the parent view. But this is not the case.
doInBackground fires all publishProgress calls and after that the main thread is blocked (activity frozen, loadbar does not rotate anymore). Is there a way to achieve what I wanted to have? I looked for solutions but alway ended up with ideas of using AsyncTask and no one had to do view-stuff as "hard staff". I am not using "get" in the AsyncTask what seems to be a problem with AsyncTask.
Here is my code for this. If you need any further information please tell me!
Is there any other way to solute this problem? Is my AsyncTask implementation not correct? I am looking for a way to load these complex views asyncronous to the parent view without blocking the main thread.
Thanks in advance!
public class LoadKraut extends AsyncTask<Integer,Kraut,Void> {
private Context context;
private LinearLayout parent;
private HashMap<String,HeadlineAlphabet> headlinesAlphabet = new HashMap<String, HeadlineAlphabet>();
private long time;
private Integer kategorie;
private char letter = 'X';
private int counter = 0;
private ProgressDialog dialog;
public LoadKraut(Context context) {
/**
* Kategorie:
* 1 - A-Z
* 2 - Notiz
* 3 - Favorit
* 4 - Giftig
*/
Log.i("Kraut", "Start thread" + (System.currentTimeMillis()-time) + "ms");
this.context = context;
this.dialog = new ProgressDialog(context);
this.time = System.currentTimeMillis();
}
#Override
protected void onPreExecute() {
dialog.setMessage("Lade Kräuter. Dieser Vorgang kann einen Moment dauern.");
dialog.show();
}
#Override
protected Void doInBackground(Integer... params) {
this.kategorie = params[0];
//Create overview
try {
DatabaseHelper databaseHelper = new DatabaseHelper(context);
Dao<Kraut,Integer> dao = databaseHelper.getKrautDAO();
parent = (LinearLayout) ((Activity) context).findViewById(R.id.ll_conainter_sv_uebersicht_kraeuter);
//setKraeuter(list, linearLayout, giftig)
long test = System.currentTimeMillis();
List<Kraut> list = new ArrayList<>();
switch (kategorie) {
case 1:
list = dao.queryForAll();
break;
case 2:
list = dao.queryBuilder().where().ne("notiz","").query();
break;
case 3:
list = dao.queryBuilder().where().eq("favorit",true).query();
break;
case 4:
list = dao.queryBuilder().where().eq("toedlichBunny",true).query();
break;
}
Log.i("Kraut","Fetching duration: " + String.valueOf(System.currentTimeMillis() - test));
Iterator<Kraut> iterator = list.iterator();
while(iterator.hasNext()) {
Kraut kraut = iterator.next();
Log.i("Kraut","called pp for" + kraut.getName());
publishProgress(kraut);
}
} catch (SQLException e) {
e.printStackTrace();
}
Log.i("Kraut", "End " + (System.currentTimeMillis()-time) + "ms");
return null;
}
#Override
protected void onProgressUpdate(Kraut... value) {
//Set all Krauts and headlines A-Z
long test = System.currentTimeMillis();
Kraut kraut = value[0];
Log.i("Kraut", String.valueOf(counter));
if((kategorie==1 || kategorie==4) && kraut.getName().charAt(0)!=letter) {
letter = kraut.getName().charAt(0);
HeadlineAlphabet letterHeadline = new HeadlineAlphabet(context);
letterHeadline.setText(String.valueOf(kraut.getName().charAt(0)));
headlinesAlphabet.put(String.valueOf(letterHeadline.getText()),letterHeadline);
parent.addView(letterHeadline);
}
KrautView krautView=null;
if(kategorie==1 || kategorie==3) {
krautView = new KrautUebersicht(context,kategorie);
} else if(kategorie==2) {
krautView = new KrautUebersichtNotiz(context);
}
if(krautView!=null) {
krautView.setKraut(kraut);
parent.addView((LinearLayout) krautView, ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
}
parent.getRootView().invalidate();
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
counter++;
Log.i("Kraut","Kraut View creation duration: " + String.valueOf(System.currentTimeMillis() - test));
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
if(kategorie==1) {
//Set Alphabet Column right side
ArrayList<String> anfangsbuchstaben = Kraut.getAnfangsbuchstaben(context);
// Do this with an xml !
for (int i = 1; i <= 26; i++) {
//Log.i("Kraut", String.valueOf(i));
String currentLetter = Helper.getCharForNumber(i);
int id = context.getResources().getIdentifier("tv_"+currentLetter.toLowerCase(),"id",context.getPackageName());
TextView textView = (TextView) ((Activity) context).findViewById(id);
//If no Kraut contains Letter
if (!anfangsbuchstaben.contains(currentLetter)) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
textView.setTextColor(context.getResources().getColor(R.color.darkgrey, context.getTheme()));
} else {
textView.setTextColor(context.getResources().getColor(R.color.darkgrey));
}
//Make clickable to jump to A-Z Headlines
} else {
textView.setOnClickListener(new JumpToLetterOnClickListener(headlinesAlphabet));
}
}
}
parent.invalidate();
if(dialog.isShowing()) {
dialog.dismiss();
}
}
}

Note that onProgressView() is called repeatedly as your AsyncTask runs. Therefore, it should be kept as short as possible. This also means that your current code is creating lots of views and adding them to the UI. Instead, you should add the view just once and then update its data in onProgressView().
Also, as Mike M. states in the comments, you should not call Thread.sleep() in onProgressView() since it runs on the UI thread. This is most likely the main reason your app is freezing.

Activity get stuck in Looper.java

One of my app's activities has ran into an issue; the problem seems to be an asynk-task, which get information from the server and generate a list of n elements in a view using that data, this, get the activity stuck in the white load screen instead of rendering the view.
No crashes or errors.
I can press back button and return to previous activity(Not freeze).
Android monitor show no cpu usage.
Here is the code.Is called at the end of onCreate()
new AsyncTask() {
#Override
protected void onPreExecute() {
mProgressDialog.show();
}
#Override
protected Object doInBackground(Object[] params) {
Document dom = null;
Detalle detalle= getIntent().getParcelableExtra("pedido");
try {
dom=DetalleToXml.getDom(detalle);
} catch (Exception e) {
e.printStackTrace();
}
return dom;
}
protected void onPostExecute(Object o) {
Document dom = (Document)o;
mProgressDialog.dismiss();
TableLayout t = (TableLayout) contentView.findViewById(R.id.grid_layout_pedido);
t.removeAllViewsInLayout();
final NodeList rows = dom.getElementsByTagName("row");
if(rows.getLength() == 0) {
Toast.makeText(DetallesPedido.this, "La búsqueda no ha tenido resultados.", Toast.LENGTH_SHORT).show();
}else{
for(int i = 0; i < rows.getLength(); i++){
Element e = (Element)rows.item(i);
LayoutInflater inflater = LayoutInflater.from(getBaseContext());
String rowid = UtilesDom.getValue(e, "rowid");
String articulo = UtilesDom.getValue(e, "articulo");
String precio_venta = UtilesDom.getValue(e, "precio_venta");
String cantidad = UtilesDom.getValue(e, "cantidad");
String descripcion = UtilesDom.getValue(e, "descripcion");
LinearLayout bigRow=(LinearLayout)inflater.inflate(R.layout.pedido_detalle,null);
TextView tv=(TextView) bigRow.findViewById(R.id.detalle_row_textView1);
tv.setText(articulo);
tv=(TextView) bigRow.findViewById(R.id.detalle_row_textView3);
tv.setText(precio_venta);
tv=(TextView) bigRow.findViewById(R.id.detalle_row_textView2);
tv.setText(cantidad);
tv=(TextView) bigRow.findViewById(R.id.detalle_row_textView4);
tv.setText(descripcion);
try {
bigRow.setId(Integer.parseInt(rowid));
} catch (Exception e2) {
e2.printStackTrace();
}
bigRow.setTag(articulo);
bigRow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String codigo = (String) v.getTag();
final Context context = v.getContext();
final int rowid = v.getId();
Intent intent = new Intent(context, DetalleFicha.class);
Bundle b = new Bundle(3);
b.putInt("rowid", rowid);
b.putInt("operation",UtilesABM.UPDATE);
b.putString("caller","DetallesPedido");
intent.putExtras(b);
intent.putExtra("pedido",getIntent().getParcelableExtra("pedido"));
loaded = false;
startActivity(intent);
}
}
);
//UtilesViews.setDefaultPadding(tv);
t.addView(bigRow);
}
}
super.onPostExecute(o);
}
}.execute(query);
By debugging i can reach the Loop.java class right after execute() and there is where gets stuck.
Any ideas of how to fix it or the cause of the problem?

You are performing very performance costly call
LinearLayout bigRow=(LinearLayout)inflater.inflate(R.layout.pedido_detalle,null);
which can take too much time, and since you are doing it in onPostExecute call, which is being called on main thread, so main thread will gets blocked if number of rows are huge and app becomes unresponsive
Solution to this is, you can use recycler view

Android: Refresh ListView every minute

I've been reading all day threads regarding this issue I came up with a strategy but can't make it work
I have a listview fetching json data from a sql server
this listview already has a on swipe refresh function
I need this listview to refresh automatically only when new row was inserted in the data base.
So I wrote a php file fetching number of rows and echoing it witha 3 second refresh (on the php itself) so every time I enter the php file I get the realtime row numbers of my table.
I'm trying to build a function inside my MainActivity:
int OldNumberOfRows = data from the php file
while(true){
int newNumberOfRows = fetch data again using that php
if(both arent equal) execute refresh command.
}
Note: I got no idea how to extract the string from my asynctask to start manipulating my code with it.
That's it in general, Iv'e added the main activity , the "outer class" (FetchNumRowAsync) calling that php the swipe class and the php itself
MainActivity:
public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {
private String TAG = MainActivity.class.getSimpleName();
private String URL = "http://troyka.esy.es/troyka/orders.php";
private SwipeRefreshLayout swipeRefreshLayout;
private ListView listView;
private SwipeListAdapter adapter;
private List<Order> orderList;
// initially offset will be 0, later will be updated while parsing the json
private int offSet = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new FetchRowNumAsync(this).execute("http://troyka.esy.es/numberofrows.php");
listView = (ListView) findViewById(R.id.listView);
//RelativeLayout.LayoutParams layout_description = new RelativeLayout.LayoutParams(50,10);
//Rl.setLayoutParams(layout_description);
swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);
orderList = new ArrayList<>();
adapter = new SwipeListAdapter(this, orderList);
listView.setAdapter(adapter);
swipeRefreshLayout.setOnRefreshListener(this);
/**
* Showing Swipe Refresh animation on activity create
* As animation won't start on onCreate, post runnable is used
*/
swipeRefreshLayout.post(new Runnable() {
#Override
public void run() {
swipeRefreshLayout.setRefreshing(true);
fetchOrders();
}
}
);
}
/**
* This method is called when swipe refresh is pulled down
*/
#Override
public void onRefresh() {
fetchOrders();
}
/**
* Fetching movies json by making http call
*/
private void fetchOrders() {
// showing refresh animation before making http call
swipeRefreshLayout.setRefreshing(true);
// appending offset to url
String url = URL + offSet;
// Volley's json array request object
JsonArrayRequest req = new JsonArrayRequest(url,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
if (response.length() > 0) {
// looping through json and adding to order list
for (int i = 0; i < response.length(); i++) {
try {
JSONObject orderObj = response.getJSONObject(i);
int rank = orderObj.getInt("rank");
String title = orderObj.getString("title");
Order m = new Order(rank, title);
orderList.add(0, m);
// updating offset value to highest value
if (rank >= offSet)
offSet = rank;
} catch (JSONException e) {
Log.e(TAG, "JSON Parsing error: " + e.getMessage());
}
}
adapter.notifyDataSetChanged();
}
// stopping swipe refresh
swipeRefreshLayout.setRefreshing(false);
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Server Error: " + error.getMessage());
Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();
// stopping swipe refresh
swipeRefreshLayout.setRefreshing(false);
}
});
// Adding request to request queue
MyApplication.getInstance().addToRequestQueue(req);
}
}
FetchRowNumAsync:
public class FetchRowNumAsync extends AsyncTask<String, Void, String> {
private Context mContext;
public FetchRowNumAsync(Context ctx){
this.mContext = ctx;
}
protected String doInBackground(String... urls)
{
String fullString = "";
try{
URL url = new URL(urls[0]);
BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
String line;
while ((line = reader.readLine()) != null) {
fullString += line;
}
reader.close();
}catch(Exception e ){
e.getMessage();
}
return fullString;
}
#Override
protected void onPostExecute(String value){
try{
((OnValueFetchedListener) mContext).onValueFetched(value);
}catch(ClassCastException e){}
}
public interface OnValueFetchedListener{
void onValueFetched(String columns);
}
}
SwipeListAdapter:
public class SwipeListAdapter extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<Order> orderList;
private String[] bgColors;
public SwipeListAdapter(Activity activity, List<Order> orderList) {
this.activity = activity;
this.orderList = orderList;
bgColors = activity.getApplicationContext().getResources().getStringArray(R.array.movie_serial_bg);
}
#Override
public int getCount() {
return orderList.size();
}
#Override
public Object getItem(int location) {
return orderList.get(location);
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_row, null);
TextView serial = (TextView) convertView.findViewById(R.id.serial);
TextView title = (TextView) convertView.findViewById(R.id.title);
serial.setText(String.valueOf(orderList.get(position).id));
title.setText(orderList.get(position).title);
String color = bgColors[position % bgColors.length];
serial.setBackgroundColor(Color.parseColor(color));
return convertView;
}
}
PHP
<?php
header("refresh: 3;");
$mysqli = new mysqli("irrelevant","irrelevant","irrelevant","irrelevant");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT COUNT(*) FROM orders";
$result = mysqli_query($mysqli,$query);
$rows = mysqli_fetch_row($result);
echo ($rows[0]);
$result->close();
$mysqli->close();
?>

Try this approach:
Create an endpoint in your server like the following:
//http://somesite.com/api/data/pull/check
Then, you can easily check this endpoint that returns some value like true or false depending on whether there is new data inserted into the db.
From the result you receive, you can then decide on whether to refresh your data on the phone by making another HTTP request or not. You always want to avoid making unnecessary requests to the server - remember users spend money every time they use their data plan (service).
I, like in the comments above, recommend having a column with a timestamp that you can check so that you only get the newly added data instead of everything!
I hope this gives you a simple idea on how to approach this issue! Good luck!

android app will not know when you have added/updated data in your table on the server until and unless you call script from app and fetch the data and update in your device.
only if your app has implemented these feature's
push notification- call Script every time you receive notification.
XMPP service- used for chat apps(which is not probably answer for
your question right now)
here is my suggestion for you
From server side:
create timestamp field in your table on server. update it with
current timestamp value every time you do changes(i.e update/add) in
the table.and when when that script is called send it across in json
and make your app save it in sqlite along with data.
server will compare for timestamp posted by app everytime with the
saved timestamp in the server for new data.
from client side:
for fist time timestamp from app will be 0. server will check it and
send the whole data along with the timestamp saved during changes in
table. save the data along with time stamp . second time when the
script is called App will be sending the timestamp that was last
saved.
with all this your app will not come to know still if new data is added until you call script and check. but atleast it will come to know if new data is received or not and whether to refresh ur screen
now comes script calling part from client side that is executing of assynch task, do it using handler to execute assynch class every minute
final Handler timerHandler = new Handler();
Runnable timerRunnable;
timerRunnable = new Runnable() {
#Override
public void run() {
new FetchRowNumAsync(context).execute(url);
timerHandler.postDelayed(timerRunnable, 60000); // run every minute
}
};
and unregister it in onDestroy()
#Override
public void onDestroyView() {
// TODO Auto-generated method stub
super.onDestroyView();
timerHandler.removeCallbacks(timerRunnable);
}

Possible incorrect referencing

I have been trying to fix this bug for 3-4 hours, and i don't really know what else to try...
Here is how the program should work:
When an alarm is set, it goes off and asks JSON parser class to fetch some numbers.
JSONParser class does exactly that, and when i put results into object and try to update the database, nothing is happening.
JSONParser returns the string with numbers, which indicates that it does actually do what it is supposed to, and also database works properly in different methods.
It is because of this, that i suspect that my reference to the object isn't good, and that is the reason that this isn't working, but i cannot see any mistakes... Here is the code:
Alarm class ( where the Ticket object is drawn from the database) :
public void onReceive(Context context, Intent intent) {
/*acquire power service manager*/
PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK,"TAG");
wl.acquire();
boolean boot = intent.getBooleanExtra("boot", false);
if(boot==true){
findTicketAndSetAlarm(context);
}
else{
Bundle b = intent.getBundleExtra("Bundle");
UUID id = UUID.fromString(b.getString("Key"));
DBHelper db = new DBHelper(context.getApplicationContext());
currentTicket = db.getTicket(id);
if(Global.isNetworkAvailable(context)){
JSONParser parser = new JSONParser(context, currentTicket,true,null);
parser.execute("http://www.millipiyango.gov.tr/sonuclar/cekilisler/sayisal/20150228.json");
}
else{
sendNotification(context,intent);
}
}
}
And here is the JSONParser class onPostExecute method:
#Override
protected void onPostExecute(String result) {
if(result == null){
if(mNotification)
Alarm.notifyUser(mContext, mTicket);
else
mActivity.notify(false);
}
else{
try {
int numbers[] = new int[6];
numbers = getJSON(numbers,result); //GETS the numbers from REST service
saveResultsToTicket(numbers);
String sResult = Global.getStringFromArray(numbers); //STRING WITH WORKING NUMBERS
if(mNotification)
Alarm.notifyUser(mContext, mTicket,sResult,mContext.getResources().getString(R.string.these_numbers_were_picked_));
else
mActivity.notify(true);
} catch (JSONException e) {
if(mNotification)
Alarm.notifyUser(mContext, mTicket);
else
mActivity.notify(false);
e.printStackTrace();
}
}
super.onPostExecute(result);
}
private void saveResultsToTicket(int[] numbers) {
mTicket.setResultNumbers(numbers);
ArrayList<Row> rows = new ArrayList<Row>();
rows = mTicket.getRows();
Iterator<Row> i = rows.iterator();
while(i.hasNext()){
Row r = i.next();
if((r.checkNumbers(numbers)).length >= 3){
mTicket.setWon(Global.WIN);
return;
}
}
mTicket.setWon(Global.LOSE);
commit();
}
private void commit() {
DBOperator dbOp = new DBOperator(mContext.getApplicationContext(), Global.UPDATE);
dbOp.execute(mTicket);
}
Thanks!

So, apparently, the method name commit is used in java, and Eclipse doesn't show any warning or error if by some chance you name your method exactly the same.
So method name was the problem i was facing...

AsyncTask displaying progress bar

I am very new to android. I got two activities A, B . Activity A parse the data from the sever and iterate through the levels. and calls the activity B through intent. Activity B takes some time to display the data so I am trying to display the progress bar. Here is my code.
public class Display extends Activity {
ProgressDialog dialog;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.attributequestions);
new asynctask().execute();
}
class asynctask extends AsyncTask<Context,Void,Void>{
Survey[] surveyque=null;
// i hace created seperated class forsurvey that has info about data
String list[];
private ProgressDialog Dialog;
#Override
protected void onPreExecute()
{
Dialog=ProgressDialog.show(Display.this, "Parsing Data", "Please wait..........");
}
#Override
protected void onPostExecute(Void unused)
{
try
{
if(Dialog.isShowing())
{
Dialog.dismiss();
}
Intent intent=getIntent();
}
catch(Exception e)
{
Log.d("Onsitev4", "error");
}
}
#Override
protected Void doInBackground(Context... params) {
try {
LinearLayout layout1 = (LinearLayout) findViewById(R.id.linearLayout1);
//getting exception here. I dont understant why
// I have declared layout params and displaying activities in another class
ButtonView c = new ButtonView();
c.layout=layout1;
c.context =getBaseContext();
DbCoreSqlSurveys surveys=new DbCoreSqlSurveys(getBaseContext());
Document doc =surveys.getSurveySet();
surveyquestions= GetSurveyLevels(doc,c );
} catch (TransformerFactoryConfigurationError e) {
e.printStackTrace();
}
return null;
}
}
public SurveyObject[] GetSurveyLevels(Document doc, ButtonView c) {
NodeList nlQuestions = doc.getElementsByTagName("Survey");
SurveyObject[] allsurveys = new SurveyObject[nlQuestions.getLength()];
for (int i = 0; i < nlQuestions.getLength(); i++){
Node survey = nlQuestions.item(i);
String f =survey.getNodeName();
Log.d("OnsiteV4", "survey " + f);
NodeList surveyChildNodes = survey.getChildNodes();
SurveyObject s=new SurveyObject();
for (int j = 0; j < surveyChildNodes.getLength(); j++){
Node surveyChild = surveyChildNodes.item(j);
String h =surveyChild.getNodeName();
Log.d("OnsiteV4", "survey child node = " + h);
if (h !="#text"){
Surveys t = Surveys.valueOf(h);
switch(t){
case KeySurvey:
s.KeySurvey=surveyChild.getTextContent();
displaySurveyLink(s.SurveyDescription,"",c,0,s.SurveyDescription,"","","","");
break;
case SurveyDescription:
s.SurveyDescription=surveyChild.getTextContent();
displaySurveyLink(s.SurveyDescription,"",c,0,s.SurveyDescription,"","","","");
break;
case SurveyUserCode:
s.SurveyUserCode=surveyChild.getTextContent();
break;
case Level1:
if(surveyChild.hasChildNodes()){
s.Level1= processLevel1Nodes(surveyChild,c,s.SurveyDescription);
}
break;
default:
break;
}
}
allsurveys[i]=s;
}
}
return allsurveys;
}
// methods iterating through levels that is not showed
private void displaySurveyLink(final String description, String tag, ButtonView c, int indentation, final String surveyDescription, final String level1description, final String level2description, final String level3description, final String level4description)
{
if (description == null || tag == null){
return;
}
final TextView tv = c.addButton(description,tag,indentation);
tv.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
final Intent intent = new Intent();
intent.setClass(v.getContext(),ActivityB.class);
intent.putExtra("KeyLevel",tv.getTag().toString());
intent.putExtra("SurveyDescription",surveyDescription);
intent.putExtra("level1description",level1description);
intent.putExtra("level2description",level2description);
intent.putExtra("level3description",level3description);
intent.putExtra("level4description",level4description);
intent.putExtra("Description",description);
if (tv.getTag() != null){
if (tv.getTag().toString() != ""){
startActivity(intent);
}
}
}
});
}
}
I am getting exception in doinbackground. I am confused . please help me..

You are getting an exception because you are accessing UI elements on a non-UI thread. The main thread that the application creates is the UI thread, and that's where all of your visual elements are created and therefore the only thread in which you should access them.
To appropriately use AsyncTask, you run your long-running operations in doInBackground, and you use onPreExecute, onPostExecute and onProgressUpdated to work with the UI (show/hide progress dialogs, update views, etc). Whenever I use an AsyncTask and I want to show progress, I override onProgressUpdated giving it parameter type Integer and I call publishProgress from doInBackground. This would require a change of the base class signature from AsyncTask<Context,Void,Void> to AsyncTask<Context,Integer,Void>. You can use other object types for this as well...I just use Integer as an example if you want to show the percentage of the task that is complete, for example.

It's becoz your code should throwing exception as you are doing UI stuff in the doinbackgound of asyc task. Please remove all the UI related work from doingbackgound method.