I tried to refer similar question on SO, but didn't got any help.
In my android app, I'm planning to implement Recent Quote the user has visited i.e. similar to recently visited pages on web.
Following are the steps I'm following:
1.) Whenever user opens any company view, fetch the company symbols from database
2.) Then store the current symbol along with dateTime in database.
3.) For all symbols fetched from database, Fetch their current value and %Change and display Company name, current value and %Change in a list.
The problem arises in the ASyncTask class as postExecute method doesn't allow it's return type to be any other than void.
Am I doing anything wrong?
Any help will be life saver !!!
String[] rsym,rcmp,rchg;
rdbM = new RecentDBManager(CompanyView.this);
try {
Calendar date1 = Calendar.getInstance();
SimpleDateFormat dateformatter = new SimpleDateFormat(
"dd/MM/yyyy HH:mm:ss");
String currentdate = dateformatter.format(date1.getTime());
rdbM.openDB();
//STEP 1
rsym = rdbM.getRecent_sym();
//STEP 2
rdbM.setData(currentsymbol, currentdate);
rdbM.closeDB();
} catch (Exception e) {
throw new Error(" *** ERROR in DB Access *** "+ e.toString());
}
//STEP 3
for(int i=0;i<rsym.length;i++)
{
DownloadRecentQuote quotetask = new DownloadRecentQuote();
recentquotetask
.execute(new String[] { "http://abc.com/stockquote.aspx?id="
+ rsym[i] });
//CURRENT VALUE and %CHANGE which should be returned from ASyncTask class
rcmp[i]=valuearr[0];
rchg[i]=valuearr[1];
}
list1 = new ArrayList<HashMap<String, String>>();
HashMap<String, String> addList1;
for (int i = 0; i < limit; i++)
{
addList1 = new HashMap<String, String>();
addList1.put(RecentSym_COLUMN, rsym[i]);
addList1.put(RecentCMP_COLUMN, rcmp[i]);
addList1.put(RecentChg_COLUMN, rchg[i]);
list1.add(addList1);
RecentAdapter adapter1 = new RecentAdapter(
CompanyView.this, CompanyView.this, list1);
listrecent.setAdapter(adapter1);
}
private class DownloadRecentQuote extends AsyncTask<String, Void, String> {
/* Fetching data for RecentQuote information */
#Override
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(
new InputStreamReader(content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
} catch (Exception e) {
e.printStackTrace();
}
}
return response;
}
#Override
protected void onPostExecute(String result) {
arr1 = result.split("#");
if (arr1[0].length() != 0) {
if (arr1[0].equals("1")) {
arr = arr1[1].split(";");
//RETURN 2 STRINGS
String valuearr[];
valuearr[0] = arr[3];
valuearr[1] = arr[6].concat("%");
//return valuearr;
}
}
}
postExecute() can't return a value because who or what would it return to? Your original method that invoked the AsyncTask is gone because your AsyncTask is running in the background. It's asynchronous meaning when AsyncTask.execute() returns it's still running in the background, and hence postExecute() can't return a value because there's nothing to return it to.
Instead your AsyncTask needs a reference back to your Activity or some other object so it can post your values back to it. In your code the lines after you call execute() can't be there because your task hasn't finished. Instead you should create a method called updateSymbol( currentPrice, percentChange), move all that code below execute() in there, and in your AsyncTask you should pass a reference to the Activity. Then call updateSymbol( currentPrice, percentChange ) from the onPostExecute() method.
But, be careful if you have a reference back to an Activity it can be destroyed while your doInBackground() is running, and when postExecute() runs it should just drop the results or not attempt to update the UI. For example, the user rotates their phone causing the Activity to be destroyed. I find it best to hold a reference to the AsyncTask in the activity so it can cancel() it if the Activity is destroyed. You can call AsyncTask.cancel() then check if your task was canceled like:
public void postExecute( String result ) {
if( !isCanceled() ) {
// do your updating here
activity.setSymbol( result );
}
}
It's really easy to create a base class for all Activities so you can easily keep track of AsyncTasks running:
public class BaseActivity extends Activity {
List<AsyncTask> runningTasks;
public void onStop() {
for( AsyncTask task : runningTasks ) {
task.cancel(true);
}
}
public AsyncTask start( AsyncTask task ) {
runningTasks.add( task );
return task;
}
public void done( AsyncTask task ) {
runningTasks.remove( task );
}
}
Some quick pointers. You don't need execute( new String[] { "blah" + blah } ). Varargs in Java allow you to do this. execute( "blah" + blah ). You also are catching exceptions and continuing without really handling them. It will be hard when something really happens because your app catches them, and just continues as if nothing happened. If you get an error you might want to provide some feedback to the user and stop trying to execute that process. Stop, show an error to the user, and let them do the next thing. Move the catch blocks to the bottom of the methods.
Essentially, AsyncTask.onPostExecute() is where you do whatever you want to do after AsyncTask's doInBackground() is executed and the execution result gets returned. This should be considered the best practice.
When AsyncTask().execute() is called from the UI thread (note that this method must be called from the UI thread), the Android framework creates a worker thread and starts running whatever you wrote in AsyncTask.doInBackground() on this worker thread. At this point (after calling new AsyncTask().execute()), the UI thread continues to execute code after new AsyncTask().execute(). So now during run time, you have two threads (UI and worker thread) both running simultaneously.
But where and when does the AsyncTask execution result get returned from the worker thread back to the UI thread?
The point where your worker thread (doInBackground()) finishes and returns to the UI thread is AysncTask.onPostExecute(). This method is guaranteed to be called by the framework on the UI thread as soon as AsyncTask finishes. In other words, we don't care where and when AsyncTask.onPostExecute() gets called at run time, we just need to guarantee it will be called ultimately at some stage in the future. This is the reason why this method does not return an execution result - instead, it requires that the execution result gets passed in as the only method parameter from doInBackground().
In addition, the Android API provides a way to return an AsyncTask execution result at coding time, AsyncTask.get():
MyAsyncTask myAsyncTask = new MyAsyncTask();
// This must be called from the UI thread:
myAsyncTask.execute();
// Calling this will block UI thread execution:
ExecutionResult result = myAsyncTask.get();
Bear in mind that AsyncTask.get() will block the calling thread's execution, and you will probably get an ANR exception if you call it on the UI thread. This is the payload of using AsyncTask.get(), by calling it on the UI thread, you are actually making your AsyncTask (worker thread) run synchronously with UI thread (by making UI thread wait). To sum up, this is doable but not recommended.
Just for future reference, because this post is a little old:
I have created an Activity class which has an onStart() method and a separate class for the AsyncTask. Based on my test, after the doInbackground() method the result will be sent to the activity first and after that onPostExecute() will run. This is because based off of logcat, I have my first response data (sent by server) first, then this response will show again from the activity and the last the message in onPostExecute() will show.
Code for the activity:
#Override
protected void onStart() {
super.onStart();
String str = "***";
if(isConnectedToInternet()){
myAsyncTask.execute();
try {
if(myAsyncTask.get())
str = myAsyncTask.getResponseMsg();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (CancellationException e) {
e.printStackTrace();
}
}
Log.i("Data returned by server2:", str);
}
AsyncTask code:
public class MyAsyncTask extends AsyncTask<Void, Void, Boolean> {
private URL url;
private HttpURLConnection conn;
private String strResponseMsg;
public MyAsyncTask(String url) throws MalformedURLException{
this.url = new URL(url);
}
#Override
protected void onPreExecute() {
Log.i("Inside AsyncTask", "myAsyncTask is abut to start...");
}
#Override
protected Boolean doInBackground(Void... params) {
boolean status = false;
try {
conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(Manager.ConnTimeout);
conn.setReadTimeout(Manager.ReadTimeout);
int responseCode = conn.getResponseCode();
Log.i("Connection oppened", "Response code is:" + responseCode);
if (responseCode == HttpURLConnection.HTTP_OK) {
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
if (in != null) {
StringBuilder strBuilder = new StringBuilder();
// Read character by character
int ch = 0;
while ((ch = in.read()) != -1)
strBuilder.append((char) ch);
// Showing returned message
strResponseMsg = strBuilder.toString();
Log.i("Data returned by server:", strResponseMsg);
status = true;
}
in.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return status;
}
#Override
protected void onPostExecute(Boolean result) {
Log.i("Inside AsyncTask", "myAsyncTask finished its task. Returning data to caller...");
}
public String getResponseMsg(){
return strResponseMsg;
}
}
Related
I am pretty new with the concept of asynctask and i have an asynctask that gets me a json from an api with parameter an then(postexecute) puts the content inside textviews to be shown(they are set visible after setting the text), the thing is i am trying to validate that the json isnt actually empty, and with my code i actually do that, but if the parameter i use is correct, the validation still detects that its empty, if i try to get it again(by pressing the button that triggers the asynctask) after 2 or three tries it will actually get it tho, i think its because i am doing it on the background, here is the asynctask
private class ConsultarDatos extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to retrieve web page. URL may be invalid.";
}
}
// onPostExecute displays the results of the AsyncTask.
#Override
protected void onPostExecute(String result) {
JSONArray ja = null;
try {
ja = new JSONArray(result);
txtNombre.setText(ja.getString(0) +" " + ja.getString(1));
txtCategoria.setText(ja.getString(2));
txtDNI.setText(ja.getString(3));
txtEstado.setText(ja.getString(4));
//working=false;
} catch (JSONException e) {
e.printStackTrace();
}
}
}
and here is what i am trying to do
btnGenerar.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
new ConsultarDatos().execute("https://api-adress/file.php?DNI=" + etDNI.getText().toString());
//while(working)
//{
//}
if (txtCategoria.getText()!="") {
btnGenerar.setVisibility(View.INVISIBLE);
etDNI.setVisibility(View.INVISIBLE);
txtCategoria.setVisibility(View.VISIBLE);
txtDNI.setVisibility(View.VISIBLE);
txtEstado.setVisibility(View.VISIBLE);
txtNombre.setVisibility(View.VISIBLE);
imgTarjeta.setVisibility(View.VISIBLE);
}
else
{
Toast.makeText(getApplicationContext(),"DNI Incorrecto",Toast.LENGTH_LONG).show();
}
}
});
as i commented i tried to do a while that would wait until the textsviews are all set but that just crashed my app
I resolved it, just moved the the visibility set and validation to the end of the onPostExecute and just to be sure i put the toast in the exception too just so the user gets some feedback
protected void onPostExecute(String result) {
JSONArray ja = null;
try {
ja = new JSONArray(result);
txtNombre.setText(ja.getString(0) +" " + ja.getString(1));
txtCategoria.setText(ja.getString(2));
txtDNI.setText(ja.getString(3));
txtEstado.setText(ja.getString(4));
if (txtCategoria.getText()!="") {
btnGenerar.setVisibility(View.INVISIBLE);
etDNI.setVisibility(View.INVISIBLE);
txtCategoria.setVisibility(View.VISIBLE);
txtDNI.setVisibility(View.VISIBLE);
txtEstado.setVisibility(View.VISIBLE);
txtNombre.setVisibility(View.VISIBLE);
imgTarjeta.setVisibility(View.VISIBLE);
}
else
{
Toast.makeText(getApplicationContext(),"DNI Incorrecto",Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),"DNI Incorrecto",Toast.LENGTH_LONG).show();
}
}
Use something like https://www.getpostman.com/ to see what the result of your API call is. Right now it seems like you don't know what you're getting back, and how consistently it comes back. You need to validate that your server is sending you back valid data.
Using a json library to parse the JSON response, such as GSON or Moshi would help you out as well. Right now you're trying to get the values based on arbitrary numbers. You could be having an exception from just one field missing, but there's not enough info to tell. Gson is fairly easy to set up in my experience: https://github.com/google/gson
Aim
In a fragment, I have a search bar which looks for online news about what the user typed. I would want to display these news (title + description + date of publication + ... etc.) in the GUI, as vertical blocks.
Implementation
Explanations
In the fragment, within the search event handling, I instanciated an asynchronous task and execute it with the good URL REST API I use to do the search.
In the asynchronous task, I make use of this REST API (thanks to the URL and some required parameters as an authorization key, etc.). When my asynchronous task gets answered, it must update the fragment's GUI (i.e.: it must vertically stack GUI blocks containing the titles, descriptions, etc. of the got news).
Sources
You will find sources in the last part of this question.
My question
In the asynchronous task (more precisely: in its function that is executed after having got the answer), I don't know how to get the calling fragment. How to do this?
Sources
Fragment part
private void getAndDisplayNewsForThisKeywords(CharSequence keywords) {
keywords = Normalizer.normalize(keywords, Normalizer.Form.NFD).replaceAll("[^\\p{ASCII}]", "");
new NetworkUseWorldNews().execute("https://api.currentsapi.services/v1/search?keyword=" + keywords + "&language=en&country=US");
}
Asynchronous task part
public class NetworkUseWorldNews extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String[] urls) {
StringBuilder string_builder = new StringBuilder();
try {
URL url = new URL(urls[0]);
HttpsURLConnection https_url_connection = (HttpsURLConnection) url.openConnection();
https_url
_connection.setRequestMethod("GET");
https_url_connection.setDoOutput(false);
https_url_connection.setUseCaches(false);
https_url_connection.addRequestProperty("Authorization", "XXX");
InputStream input_stream = https_url_connection.getInputStream();
BufferedReader buffered_reader = new BufferedReader(new InputStreamReader(input_stream));
String line;
while((line = buffered_reader.readLine()) != null) {
string_builder.append(line);
}
buffered_reader.close();
} catch (IOException e) {
e.printStackTrace();
}
return string_builder.toString();
}
#Override
protected void onPostExecute(String result) {
try {
JSONObject news_response_http_call = new JSONObject(result);
switch(news_response_http_call.getString("status")) {
case "ok":
JSONArray news = news_response_http_call.getJSONArray("news");
for(int i = 0; i < news.length(); i++) {
JSONObject a_news = news.getJSONObject(i);
String title = a_news.getString("title");
String description = a_news.getString("description");
String date_of_publication = a_news.getString("published");
String url = a_news.getString("url");
String image = a_news.getString("image");
System.out.println(title + ": " + date_of_publication + "\n" + image + "\n" + url + "\n" + description);
WorldNewsFragment world_news_fragment = ...;
}
break;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
If I am right, you want to update View of your caller Fragment. if FragmentA called service then FragmentA should be update.
However the approach you are asking is wrong. Instead of getting caller Fragment in your AsyncTask response. You should do it with Callback.
So now you will need to pass callback in AsyncTask. So instead of posting full code, here are already answers with this problem.
Finally your calling syntax will look like.
NetworkUseWorldNews task = new NetworkUseWorldNews(new OnResponseListener() {
#Override
public void onResponse(String result) {
// Either get raw response, or get response model
}
});
task.execute();
Actually I am still very unclear about your question. Let me know in comments if you have more queries.
Must checkout
Retrofit or Volley for calling Rest APIs
Gson for parsing JSON response automatically to models
This is the method which I use to get values.
#Override
protected Void doInBackground(String... params) {
try {
Intent intent = getIntent();
String dvlaNumFin = intent.getStringExtra("dvlaNumber");
final TextView outputView = (TextView) findViewById(R.id.showOutput);
final URL url = new URL("https://dvlasearch.appspot.com/DvlaSearch?licencePlate="+dvlaNumFin+"&apikey=");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("USER-AGENT", "Mozilla/5.0");
connection.setRequestProperty("ACCEPT-LANGUAGE", "en-US,en;0.5");
final StringBuilder output = new StringBuilder(String.valueOf(url));
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line = "";
StringBuilder responseOutput = new StringBuilder();
System.out.println("output===============" + br);
while ((line = br.readLine()) != null) {
responseOutput.append(line);
}
br.close();
HandleJSON obj = new HandleJSON("");
obj.readAndParseJSON(responseOutput.toString());
output.append(System.getProperty("line.separator") + "\n" + System.getProperty("line.separator") + "Make : " + obj.getMake() + "\nModel : " + obj.getModel());
output.append("\nSix Month Rate : " + obj.getSixMonthRate() + "\nTwelve Month Rate : " + obj.getTwelveMonthRate() + "\nDate of First Registration : " + obj.getDateofFirstRegistrationegistration());
output.append("\nYear of Manufacture : " + obj.getYearOfManufacture() + "\nCylinder Capacity : " + obj.getCylinderCapacity() + "\nCO2 Emmissions : " + obj.getCo2Emissions());
output.append("\nVIN number : " + obj.getVin() + "\nTransmission type : " + obj.getTransmission());
DVLAresult.this.runOnUiThread(new Runnable() {
#Override
public void run() {
outputView.setText(output);
progress.dismiss();
}
});
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
I would like to use obj.getMake() and so on, the values from JSON. But do not understand how to do it, or return it. I know should be return value, or by using final.
Nice and simple. Make your AsyncTask return a value:
public class TestClass extends AsyncTask<Void, Void, String>{
#Override
protected String doInBackground(String... params) {
//rest of code
return output.toString();
}
}
Now all you have to do is call .get() method after calling .execute()
TestClass tc = new TestClass();
tc.execute();
String output = tc.get();
Very Very Important Note
By calling .get() right after .execute() your UI thread will be blocked until the AsyncTask is done. This is counter intuitive to the purpose of AsyncTask. One of the solutions to this problem is adding a callback interface to the AsyncTask which will be called upon finishing and call the .get() method in the implementation of that interface. For an example on how to design a callback interface see here.
FOG
Simply implement onPostExecute inside your AsyncTask class :)
for example :
#Override
protected void onPostExecute(String makeValue) {
// remember this method gets called on main thread
letsCallFogsMethod(makeValue); //call your method and pass the make value here :)
}
Thats it buddy :)
Now how come this onPostExecute is getting any value???
You have to return it from doInBackground method dude :)
like
#Override
protected String doInBackground(String... params) {
//after all bra bla simply say
return obj.getMake();
}
Do you notice any change in your doInBackground signature buddy?? Yeah I changed from Void to String :)
By writing String you are informing that when you are done executing doInBackground you will return a string to onPostExecute :)
So if I write as it is in the answer will it work ?? Nope.
Given that you have specified Void in your doInBackground your Async task signature might look something like
private class FogsAsyncTask extends AsyncTask<bla,blah,Void> {
Can you see the last Void??? :) But now you have chnaged doInBackground isn't it so update the AsyncTask signature as well :)
private class FogsAsyncTask extends AsyncTask<bla,blah,String> {
Now it should work fine :) Happy coding buddy :) Hope my answer helped you :)
You can get the output on onPostExecute method just override the method and get the output on it
AsyncTask has three (main) methods, onPreExecute, doInBackground and onPostExecute. Only doInBackGround runs on a background thread, the other two run on the UI thread. (there is also onProgressUpdate but I will skip it here)
In your case, return anything you want in doInBackground method. That return value will be the input param for onPostExecute. There you can call any other (reachable) method you want. Mind that you'd be running inside the UI thread at that time.
I am developing an android application that consumes web service , the service output is XML
I am connecting to the web service using this code
public String converse(String host, int port, String path)
throws IOException, URISyntaxException {
BufferedReader in = null;
String serviceResponse = null ;
try {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
String serviceUrl = "http://"+host+":"+port+path;
System.out.println("service url "+serviceUrl);
request.setURI(new URI(serviceUrl));
System.out.println("Request "+request.toString());
HttpResponse response = client.execute(request);
in = new BufferedReader
(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
serviceResponse = sb.toString();
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return serviceResponse;
}
when the application launches with WI-FI every thing works fine and when I restart the application with 3G connection it hangs and displays a the following dialog
In addition to this code I am using this method inside another method
public void fillAdapter() {
//calling web service using the mentioned method
}
And this function used inside an async task to fill ListView adapter
protected class AsyncLoading extends AsyncTask<Void,Void, BaseModel[]>{
#Override
protected void onPreExecute(){
pd =ProgressDialog.show(BaseListActivity.this, "loading in progress", "waiting .");
}
#Override
protected BaseModel[] doInBackground(Void... params) {
fillAdapter();
return listItems;
}
#Override
protected void onPostExecute(BaseModel[] doc){
//list.setAdapter(doc);
if(doc != null) {
if(doc.length > 0 ) {
if(doc[0] instanceof Activity)
adapter = new OffersListAdapter(getApplicationContext(),doc);
else if (doc[0] instanceof Offer)
adapter = new OffersListAdapter(getApplicationContext(),doc);
else if (doc[0] instanceof Branch) {
adapter = new BranchListAdapter(getApplicationContext(),doc);
Log.i("Branch"," Added Branch");
}else if (doc[0] instanceof Consolation) {
adapter = new ListAdapter(getApplicationContext(),doc);
adapter.setDisplayImage(false);
}else if ( doc[0] instanceof Event) {
adapter = new EventListAdapter(getApplicationContext(),doc);
}
else
adapter = new ListAdapter(getApplicationContext(),doc);
}//end if doc != null
list.setAdapter(adapter);
}
handler.sendEmptyMessage(0);
}
I saw this post but I don't have a good result I'm working on this problem for 2 days
with my thanks in advance .
Note : this problem often appears the first time the application connects to the service after that if I pressed wait and the application continued then al other activities consuming the web service will work fine
I think you have low speed connection of 3G compared to Wi-Fi.So Use Asynctask to load data from server in seperate thread rather than main thread.It is good idea to show ProgressDialog while fetching the data.
And In some cases Apis will work in Wi-Fi and may not in 3G connection.So test Your url in Device browser also to make it confirm
You should use an AsyncTask for every task that could take some time to be executed. See http://developer.android.com/reference/android/os/AsyncTask.html
The problem i am seeing with your code is you are not doing network operation in Thread.
So if you perform asynchronous operation on Main thread,application will display above dialog if it don't receive response in 5 seconds.In your case 3g connection may be taking more than 5 seconds to return response.
Best bet is include above code in Thread!!
I have solved the problem , that I have a splash screen activity inside which I use C2DM and register the device in that activity using service
registrationIntent.putExtra("app", PendingIntent.getBroadcast(getApplicationContext(), 0, new Intent(), 0));
registrationIntent.putExtra("sender", "someemailaddress#gmail.com");
startService(registrationIntent);
I put this code inside an asyncTask and didn't block the UI
Thanks for every one who tried to help me
I'm using using AsyncTask to download data over internet and I have a little problem. I need to be able to start one AsyncTask a few times, that's why I'm creating a new instance everytime,but the thing that I notice is that it's working without any problem the first three or four times,but after that my AsyncTask is stuck on onPreExecute() and doing nothing after that. Am I doing something wrong ? (Actually I am using two AsyncTasks one after another just for testing purposes). Here is the sample code which I'm using :
this is how I start the AsyncTasks :
if (index == 1) {
//Login - first way
new FirstSync().execute(Synchronization.this);
} else if (index == 2) {
//SyncWithHash - second way
SyncWithHash syncHash = new SyncWithHash();
syncHash.execute(Synchronization.this);
} else if (index == 3) {
//Deactivate Collection - third way
deactivateColl = new DeactivateCollection();
deactivateColl.execute(Synchronization.this);
}
I did try with three different ways to start the asyncTask,but no change. Here is my AsyncTask :
// Sync With Hash
public class SyncWithHash extends AsyncTask <Context, Integer, Void> {
#Override
protected Void doInBackground(Context... arrContext) {
try {
String charset = "UTF-8";
hash = getAuthHash();
SharedPreferences lastUser = PreferenceManager.getDefaultSharedPreferences(Synchronization.this);
int userId = lastUser.getInt("lastUser", 1);
systemDbHelper = new SystemDatabaseHelper(Synchronization.this, null, 1);
systemDbHelper.initialize(Synchronization.this);
String sql = "SELECT dbTimestamp FROM users WHERE objectId=" + userId;
Cursor cursor = systemDbHelper.executeSQLQuery(sql);
if (cursor.getCount() < 0) {
cursor.close();
} else if (cursor.getCount() > 0) {
cursor.moveToFirst();
timeStamp = cursor.getString(cursor.getColumnIndex("dbTimestamp"));
Log.d("", "timeStamp : " + timeStamp);
}
String query = String.format("debug_data=%s&"
+ "client_auth_hash=%s&" + "timestamp=%s&"
+ "client_api_ver=%s&"
+ "set_locale=%s&" + "device_os_type=%s&"
+ "device_sync_type=%s&"
+ "device_identification_string=%s&"
+ "device_identificator=%s&" + "device_resolution=%s",
URLEncoder.encode("1", charset),
URLEncoder.encode(hash, charset),
URLEncoder.encode(timeStamp, charset),
URLEncoder.encode(clientApiVersion, charset),
URLEncoder.encode(locale, charset),
URLEncoder.encode(version, charset),
URLEncoder.encode("14", charset),
URLEncoder.encode(version, charset),
URLEncoder.encode(deviceId, charset),
URLEncoder.encode(resolution, charset));
SharedPreferences useSSLConnection = PreferenceManager
.getDefaultSharedPreferences(Synchronization.this);
boolean useSSl = useSSLConnection.getBoolean("UseSSl", true);
if (useSSl) {
UseHttpsConnection(url, charset, query);
} else {
UseHttpConnection(url, charset, query);
}
} catch (Exception e2) {
e2.printStackTrace();
}
return null;
}
#Override
protected void onProgressUpdate(Integer... progress) {
//cancelDialog.setProgress(progress[0]);
}
#Override
protected void onCancelled() {
Log.d("","ON CANCELLED");
}
#Override
protected void onPreExecute()
{
Log.d("","ON PRE EXECUTE");
// myProgress = 0;
}
#Override
protected void onPostExecute(Void v) {
Log.d("","ON POST EXECUTE");
}
}
So any ideas why it's happening and which is the best way to be able to use an AsyncTask a few times without any exceptions and bugs like the one that I get.
And another question : Is there anything in AsyncTask which can cause my connection to be Reset by peer , because I'm getting this error too (not every time).
Thanks a lot!
I think your doInBackground() is hanging. Make log statement when its entered and when its exited and check.
In the old days AsyncTask had a pool of threads, so if a doInBackground() hung, then it didnt affect the other AsyncTasks. That changed AFAIK with Android 2.2 or 2.3 to that a single thread took care of all AyncTasks, one at a time. Therefore, if your doInBackground() is hanging it might affect the next AsyncTasks being started and the will hang right after onPreExecute().
Edit: It was changed from a single thread, to multiple, and then back to a single thread:
http://developer.android.com/reference/android/os/AsyncTask.html#execute%28Params...%29 "When first introduced, AsyncTasks were executed serially on a single background thread. Starting with DONUT, this was changed to a pool of threads allowing multiple tasks to operate in parallel. After HONEYCOMB, it is planned to change this back to a single thread to avoid common application errors caused by parallel execution."
If you really want an indefinite lot of stuff to 'hang' in parralel, then don't use AsyncTask. Use good old threads, which, when they need to update the GUI, fire off a Runnable to be runned on the GUI thread:
Button knap1, knap2, knap3;
...
Runnable r=new Runnable() {
public void run() {
// Do some stuff than hangs
try { Thread.sleep(10000); } catch (InterruptedException ex) {}
System.out.println("færdig!");
// Update GUI thread
Runnable r2=new Runnable() {
public void run() {
knap3.setText("færdig!");
}
};
runOnUiThread(r2);
}
};
new Thread(r).start();
(example from http://code.google.com/p/android-eksempler/source/browse/trunk/AndroidElementer/src/eks/asynkron/Asynkron1Thread.java?spec=svn109&r=109)
It might be happening because you are synchronizing on an object "Synchronization.this'.
Also noticed you are not closing the cursor which you opened.