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Abort Jsoup request [duplicate]

I use an async task to upload an image and get some results.
While uploading the image I see a progress dialog, written in onPreExecute() method like this:
protected void onPreExecute() {
uploadingDialog = new ProgressDialog(MyActivity.this);
uploadingDialog.setMessage("uploading");
uploadingDialog.setCancelable(true);
uploadingDialog.show();
}
Ok when I press the back button, obviously the dialog disappears because of the setCancelable(true).
But (obviously) the async task doesn't stop.
So how can I fix this? I want to cancel both dialog and async task when I press the back button. Any ideas?

From SDK:
Cancelling a task
A task can be cancelled at any time by invoking cancel(boolean).
Invoking this method will cause subsequent calls to isCancelled()
to return true.
After invoking this method, onCancelled(Object), instead of
onPostExecute(Object) will be invoked after doInBackground(Object[]) returns.
To ensure that a task is cancelled as quickly as possible,
you should always check the return value of isCancelled() periodically from
doInBackground(Object[]), if possible (inside a loop for instance.)
So your code is right for dialog listener:
uploadingDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
public void onCancel(DialogInterface dialog) {
myTask.cancel(true);
//finish();
}
});
Now, as I have mentioned earlier from SDK, you have to check whether the task is cancelled or not, for that you have to check isCancelled() inside the onPreExecute() method.
For example:
if (isCancelled())
break;
else
{
// do your work here
}

FOUND THE SOLUTION:
I added an action listener before uploadingDialog.show() like this:
uploadingDialog.setOnCancelListener(new DialogInterface.OnCancelListener(){
public void onCancel(DialogInterface dialog) {
myTask.cancel(true);
//finish();
}
});
That way when I press the back button, the above OnCancelListener cancels both dialog and task. Also you can add finish() if you want to finish the whole activity on back pressed. Remember to declare your async task as a variable like this:
MyAsyncTask myTask=null;
and execute your async task like this:
myTask = new MyAsyncTask();
myTask.execute();

I spent a while figuring this out, all I wanted was a simple example of how to do it, so I thought I'd post how I did it. This is some code that updates a library and has a progress dialog showing how many books have been updated and cancels when a user dismisses the dialog:
private class UpdateLibrary extends AsyncTask<Void, Integer, Boolean>{
private ProgressDialog dialog = new ProgressDialog(Library.this);
private int total = Library.instance.appState.getAvailableText().length;
private int count = 0;
//Used as handler to cancel task if back button is pressed
private AsyncTask<Void, Integer, Boolean> updateTask = null;
#Override
protected void onPreExecute(){
updateTask = this;
dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
dialog.setOnDismissListener(new OnDismissListener() {
#Override
public void onDismiss(DialogInterface dialog) {
updateTask.cancel(true);
}
});
dialog.setMessage("Updating Library...");
dialog.setMax(total);
dialog.show();
}
#Override
protected Boolean doInBackground(Void... arg0) {
for (int i = 0; i < appState.getAvailableText().length;i++){
if(isCancelled()){
break;
}
//Do your updating stuff here
}
}
#Override
protected void onProgressUpdate(Integer... progress){
count += progress[0];
dialog.setProgress(count);
}
#Override
protected void onPostExecute(Boolean finished){
dialog.dismiss();
if (finished)
DialogHelper.showMessage(Str.TEXT_UPDATELIBRARY, Str.TEXT_UPDATECOMPLETED, Library.instance);
else
DialogHelper.showMessage(Str.TEXT_UPDATELIBRARY,Str.TEXT_NOUPDATE , Library.instance);
}
}

create some member variables in your activity like
YourAsyncTask mTask;
Dialog mDialog;
use these for your dialog and task;
in onPause() simply call
if(mTask!=null) mTask.cancel();
if(mDialog!=null) mDialog.dismiss();

I would like to improve the code. When you canel the aSyncTask the onCancelled() (callback method of aSyncTask) gets automatically called, and there you can hide your progressBarDialog.
You can include this code as well:
public class information extends AsyncTask<String, String, String>
{
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected String doInBackground(String... arg0) {
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
this.cancel(true);
}
#Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
}
#Override
protected void onCancelled() {
Toast.makeText(getApplicationContext(), "asynctack cancelled.....", Toast.LENGTH_SHORT).show();
dialog.hide(); /*hide the progressbar dialog here...*/
super.onCancelled();
}
}

Most of the time that I use AsyncTask my business logic is on a separated business class instead of being on the UI. In that case, I couldn't have a loop at doInBackground(). An example would be a synchronization process that consumes services and persist data one after another.
I end up handing on my task to the business object so it can handle cancelation. My setup is like this:
public abstract class MyActivity extends Activity {
private Task mTask;
private Business mBusiness;
public void startTask() {
if (mTask != null) {
mTask.cancel(true);
}
mTask = new mTask();
mTask.execute();
}
}
protected class Task extends AsyncTask<Void, Void, Boolean> {
#Override
protected void onCancelled() {
super.onCancelled();
mTask.cancel(true);
// ask if user wants to try again
}
#Override
protected Boolean doInBackground(Void... params) {
return mBusiness.synchronize(this);
}
#Override
protected void onPostExecute(Boolean result) {
super.onPostExecute(result);
mTask = null;
if (result) {
// done!
}
else {
// ask if user wants to try again
}
}
}
public class Business {
public boolean synchronize(AsyncTask<?, ?, ?> task) {
boolean response = false;
response = loadStuff(task);
if (response)
response = loadMoreStuff(task);
return response;
}
private boolean loadStuff(AsyncTask<?, ?, ?> task) {
if (task != null && task.isCancelled()) return false;
// load stuff
return true;
}
}

I had a similar problem - essentially I was getting a NPE in an async task after the user had destroyed the activity. After researching the problem on Stack Overflow, I adopted the following solution:
volatile boolean running;
public void onActivityCreated (Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
running=true;
...
}
public void onDestroy() {
super.onDestroy();
running=false;
...
}
Then, I check "if running" periodically in my async code. I have stress tested this and I am now unable to "break" my activity. This works perfectly and has the advantage of being simpler than some of the solutions I have seen on SO.

You can just ask for cancellation but not really terminate it. See this answer.

How to cancel AsyncTask
Full answer is here - Android AsyncTask Example
AsyncTask provides a better cancellation strategy, to terminate currently running task.
cancel(boolean mayInterruptIfitRunning)
myTask.cancel(false)- It makes isCancelled returns true. Helps to cancel the task.
myTask.cancel(true) – It also makes isCancelled() returns true, interrupt the background thread and relieves resources .
It is considered as an arrogant way, If there is any thread.sleep() method performing in background thread, cancel(true) will interrupt background thread at that time. But cancel(false) will wait for it and cancel task when that method completes.
If you invoke cancel() and doInBackground() hasn’t begun execute yet. onCancelled() will invoke.
After invoking cancel(…) you should check value returned by isCancelled() on doInbackground() periodically. just like shown below.
protected Object doInBackground(Params… params) {
while (condition)
{
...
if (isCancelled())
break;
}
return null;
}

show progressdialog not showing in asyctask

During android app onCreate I have a bunch of code that can be slow on some older devices. I want to have a progressdialog display while all the init code runs. Dialog won't show if called from onCreate because further code blocks the UI. So it needs to go into an AsyncTask.
This is my task.
class startupTask extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
pd = new ProgressDialog(mainContext);
pd.setMessage("Starting up. Please wait...");
pd.setIndeterminate(true);
pd.setCancelable(false);
pd.show();
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... params) {
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
pd.show();
runInit();
}
});
return null;
}
#Override
protected void onPostExecute(Void result) {
if (pd != null) {
pd.dismiss();
}
super.onPostExecute(result);
}
}
But the dialog still does not show? runInit is the usual slow startup code. It needs to run on the UI.
If I remove the pd.dismiss call the progress dialog does appear once the init codeis finished, so it is being created OK, just not displaying.
According to other posts the above code is the right way to do it, but when called from onCreate it does not seem to work?
Any ways to force a dialog to display after a call to show? Any way I can get the dialog to show and wait until it is visible before continuing?
Thanks for any help.
EDIT: In the end I just had to bite the bullet and reorganise code so that only the slow non UI code was inside the AsyncTask. This got it working.

What's your runInit is doing? You're running on the UI thread, it's being blocked the same way.

onPreExecute(), onPostExecute() and onProgressUpdate() have access to the UI Thread, but doInBackground() doesn't.
if runInit() does something on the UI it's being blocked and may be generating an exception that you're ignoring.
you should do operations on doInBackground and use publishProgress() to send to onProgressUpdate() data that you want to update to your UI / ProgressBar Status.
here's an example:
new AsyncTask<Void,Object,Void>()
{
#Override
protected Void doInBackground(Void... params)
{
Object[] _progress = new Object[]{"Decompressing", 1};
publishProgress(_progress);
}
#Override
protected void onPostExecute(Void params)
{
}
#Override
protected void onPreExecute()
{
}
#Override
protected void onProgressUpdate(Object... values)
{
txtProgress.setText(values[0].toString());
progressBar.setProgress(Integer.parseInt(values[1].toString()));
}
}.execute();

How to display a dialog to wait for user to continue in an AsyncTask?

I have an AsyncTask that does a bunch of stuff in the doInBackground() portion, and in between that bunch of stuff, I need to wait for the user to physically do something before I can continue. How do I popup some dialog for the user to click OK before continuing?
Thanks!

in between that bunch of stuff, I need to wait for the user to
physically do something before I can continue.
You aren't supposed to do that in doInBackground method, You need to do that in onPostExecute(); Interaction with the user should be done in onPostExecute.
What you can do here?
Divide your code in 2 parts, perform the code that has to be done until users Interaction in the background in doInBackground, make user Interact do that in onPostExecute, after that for rest of remaining code you can use another AsyncTask.

class LoadData extends AsyncTask<Object, Object, Object>
{
#Override
protected Object doInBackground(Object... p_params)
{
// Your background code
return null;
}
#Override
protected void onPreExecute()
{
// Display Progress dialog with cancelable false
super.onPreExecute();
}
#Override
protected void onPostExecute(Object p_result)
{
// Dismiss Progress dialog
super.onPostExecute(p_result);
}
}

If you want to put wait dialog in between doInBackground section then you can try following code:
#Override
protected Void doInBackground(Void... params) {
activity.runOnUiThread(new Runnable() {
#Override
public void run() {
final Dialog dialog = new Dialog(activity);
dialog.setTitle("Demo");
Button button = new Button(activity);
button.setText("Press For Process..");
dialog.setContentView(button);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(activity, "Perform Task",
Toast.LENGTH_LONG).show();
// You can perform task whatever want to do after
// on user press the button
dialog.dismiss();
}
});
dialog.show();
}
});
return null;
}

Android: Progress dialog not shown at 1st time (using Thread or AsyncTask for longDuration operation)

I have problem in my app with progress dialog in AsyncTask:
my AsyncTask is doing some geting data from internet in doInBackGround(), I am starting progress dialog in onPreExecute(), finish dialog in onPostExecute().
I execute this asyncTask when click on Button. 1st time When I click this button (long operation takes place) progress dialog is not shown. But next times Progress dialog is shown normaly.
What can be the problem that 1st time of running AsyncTask, progress dialog isnt shown ?
this is onClick method:
public void onClickFind(View view){
new Task_Search().execute();
}
This is task Task_Search:
private class Task_Search extends AsyncTask<Void, Void, Void> {
#SuppressWarnings("deprecation")
protected void onPreExecute() {
showDialog(DIALOG_TASKING);
}
protected Void doInBackground(Void... unused) {
//some geting of web content here
}
#SuppressWarnings("deprecation")
protected void onPostExecute(Void unused) {
dismissDialog(DIALOG_TASKING);
}
}
progress dialog defined in MainActivity:
#SuppressWarnings("deprecation")
#Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_TASKING:
mSearchDialog = new ProgressDialog(this);
mSearchDialog.setMessage("Searching for field number..");
mSearchDialog.setCancelable(true);
return mSearchDialog;
}
return super.onCreateDialog(id);
}
Before of using AsyncTask I used separate Thread for downloading data instead: in onClick, I started first progressDialog then Thread, when Thread finished also progressDialog was stoped,
Behaviour was same:
1st time of click on Button dialog wasnt shown, next times its shown.
Anybody who can help ?

I cant see you calling show() on the dialog.
Replace
#SuppressWarnings("deprecation")
protected void onPreExecute() {
showDialog(DIALOG_TASKING);
}
with
#SuppressWarnings("deprecation")
protected void onPreExecute() {
showDialog(DIALOG_TASKING).show();
}

Do not call showDialog insode onPreExecute().
AsyncTask provides publishProgress() method which can be invoked from doInBackground() to publish updates on the UI thread.

Okay,
I created in MainActivity my own methods:
public void showProgressDialog() {
if (mProgressDialog == null) {
mProgressDialog = new ProgressDialog(this);
mProgressDialog.setMessage("Searching for field number..");
mProgressDialog.show();
return;
}else{
mProgressDialog.setMessage("Searching for field number..");
mProgressDialog.show();
return;
}
}
also:
public void closeProgressDialog() {
if (mProgressDialog != null) {
mProgressDialog.dismiss();
}
return;
}
I changed AsyncTask following:
private class Task_Search extends AsyncTask<Void, Void, Void> {
protected void onPreExecute() {
// showDialog(DIALOG_TASKING);
showProgressDialog();
}
protected Void doInBackground(Void... unused) {
//Some long duration stuff here
}
protected void onPostExecute(Void unused) {
//dismissDialog(DIALOG_TASKING);
closeProgressDialog();
}
}
mProgressDialog is a private member of MainActivity
private ProgressDialog mProgressDialog;
Situation is same: wheck onClick on button: 1st time ProgressDialog stuck, next times it works perfect

ProgressBar display with some delay in on click of option menu

I am facing the issue with displaying progressbar onItem selected in option menu.
My code is here:
case R.id.mnuLogout:
showDialog(Constants.PROGRESS_DIALOG);
closeOptionsMenu();
if(MyApp.IsLoggedOut())
handler.sendEmptyMessage(Constants.LOGOUT);
else
handler.sendEmptyMessage(Constants.ERROR_MSG);
Progressbar is displayed after completion of IsLogged method.

You're calling get() right after the AsyncTask as executed and lose asynchronous behavior because this method waits until task is finished. You should add all the code in try/catch block to AsyncTask.onPostExecute() method and also dismiss the dialog from this method.
void doLogout() {
new LogoutTask().execute();
}
void dispatchLogoutFinished() {
dismissDialog(Constants.PROGRESS_DIALOG);
if (MyApp.IsLoggedOut()) {
// do something
} else {
// do something else
}
}
private class LogoutTask extends AsyncTask<Void, Void, Void> {
protected void onPreExecute() {
TheActivity.this.showDialog(Constants.PROGRESS_DIALOG);
}
protected Void doInBackground(Void... params) {
return null;
}
protected void onPostExecute(Long result) {
TheActivity.this.dispatchLogoutFinished();
}
}
And I don't think you need to send messages to the handler. The dispatchLogoutFinished() is executed on the UI thread, so there's no need for synchronization.