private class Test extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
Log.d("test", "called1");
}
#Override
protected Void doInBackground(Void... params) {
Log.d("test", "called2");
return null;
}
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
Log.d("test", "called3");
}
}
and output:
test:called1
Why other methods never don't called when Service work on background? If service stop, then all method calls and output:
test:called1
test:called2
test:called3
I guess you are testing on android 3.x or newer and you are simply affected by the change made to the way AsyncTask is executed.
This is how I handle this in my code to always work the same fully parallel:
if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ) {
new Test().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
} else {
new Test().execute();
}
Basically change in AsyncTask appeared in Honeycomb (see Android SDK docs here in "Order of execution" section), so before that, you launch it as usual, for HC and up, use executeOnExecutor() if you do not like new behaviour (noone does, I think)
Related
I use AsyncTask in my App for download a url. I use a ProgressDialog on onPreExecute() for waiting.
But I cant see ProgressDialog while process finish and i see it for a moment. want to see it while downloading not after that.
can any one help me.
thanks
my code is like this:
private class loadMoreListView extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
// Showing progress dialog before sending http request
pDialog = new ProgressDialog(SingleMenuItemActivity.this);
pDialog.setMessage("Please Wait ...");
pDialog.isIndeterminate();
pDialog.setCancelable(false);
pDialog.show();
}
protected Void doInBackground(Void... unused) {
runOnUiThread(new Runnable() {
public void run() {
// do something for downloading
}
});
return (null);
}
protected void onPostExecute(Void unused) {
// closing progress dialog
pDialog.dismiss();
}
}
runOnUiThread(new Runnable() {
public void run() {
// do something for downloading
}
// do something for downloading, inside runOnUiThread, is wrong. runOnUiThread makes "do something for downloading" run on the UI Thread, and your application should crash for NetworkOnMainThreadException, you the app runs on a device with a version of android grater than GingerBread. Differently it will block the ui thread preventing him to draw your progress bar
The problem is in
runOnUiThread(new Runnable() {
public void run() {
// do something for downloading
}
});
ProgressDialog will not update if the UI thread is still busy. There are many examples in SO for that.
I don't understand why do you need UIthread.
And as a rule of thumb - if you need Progress dialog, you need to let run asynctask in background thread,as it always do.Read the document
http://developer.android.com/reference/android/os/AsyncTask.html
You can use the below example
http://www.androidhive.info/2012/01/android-json-parsing-tutorial/
Firstly notice the "#override" header attached to all the AsyncTask Implemented methods e.g.
private class loadMoreListView extends AsyncTask<Void, Void, Void> {
ProgressDialog pDialog;
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pDialog = new ProgressDialog(SingleMenuItemActivity.this);
pDialog.setMessage("Please Wait ...");
pDialog.isIndeterminate();
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
return null;
}
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
pDialog.cancel();
}
}
Also Remove this from doInBackground unless you must do something on the UI.
runOnUiThread(new Runnable() {
public void run() {
// do something for downloading
}
});
You cannot do something for downloading on the runOnUiThread. doInBackground is meant for running background tasks like downloads etc. not visible to the UI.
I'm working on my first android app and I'm trying to use Quickblox.com as my backend.
In order to use it, I need to authorize the app by creating a session using their SDK.
So, I have the following code:
// Initialize QuickBlox application with credentials.
QBSettings.getInstance().fastConfigInit(Consts.APP_ID, Consts.AUTH_KEY, Consts.AUTH_SECRET);
// Authorize application
QBAuth.createSession(new QBCallback() {
#Override public void onComplete(Result result) {}
#Override
public void onComplete(Result result, Object context) {
if (result.isSuccess()) {
showMainScreen();
} else {
// print errors that came from server
Toast.makeText(getBaseContext(), result.getErrors().get(0), Toast.LENGTH_SHORT).show();
progressBar.setVisibility(View.INVISIBLE);
}
}
}, QBQueries.QB_QUERY_AUTHORIZE_APP);
This code works well with an emulator, but it doesn't work if I try with a real android phone. I have a connection timeout error. I think I need to make this kind of requests (Web Services) in the background right?
So I tried to use the AsyncTask to make the request to QB in the background, and changed the code to this:
new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params) {
// Initialize QuickBlox application with credentials.
QBSettings.getInstance().fastConfigInit(Consts.APP_ID, Consts.AUTH_KEY, Consts.AUTH_SECRET);
// Authorize application
QBAuth.createSession(new QBCallback() {
#Override public void onComplete(Result result) {}
#Override
public void onComplete(Result result, Object context) {
if (result.isSuccess()) {
showMainScreen();
} else {
// print errors that came from server
Toast.makeText(getBaseContext(), result.getErrors().get(0), Toast.LENGTH_SHORT).show();
progressBar.setVisibility(View.INVISIBLE);
}
}
}, QBQueries.QB_QUERY_AUTHORIZE_APP);
return null;
}
}.execute();
I've seen a lot of similar questions here at SO, but I can't seem to find an answer that works with my code. I saw that functions that deal with the UI need to be called from the main thread, so I suppose that the code I have inside
onComplete(Result result, Object context)
should be inside a block like this right?
runOnUiThread(new Runnable()
{
public void run()
{
// code here
}
});
But I tried that as well and it didn't work. Any guesses?
I believe the problem is not because of the Toast and showMainScreen(). It still fails with this code:
// Initialize QuickBlox application with credentials.
QBSettings.getInstance().fastConfigInit(Consts.APP_ID, Consts.AUTH_KEY, Consts.AUTH_SECRET);
QBAuth.createSession(new QBCallback() {
#Override
public void onComplete(Result arg0, Object arg1) {
// TODO Auto-generated method stub
}
#Override
public void onComplete(Result arg0) {
// TODO Auto-generated method stub
}
}, QBQueries.QB_QUERY_AUTHORIZE_APP);
But it doesn't fail if I just create the QBCallback object, without passing it to the QBAuth.createSession function.
You can't show a Toast in doInBackground of AsyncTask as it is a different threat and not the main UI thread.
To show a toast or any UI related task you have to do it in onPostExecute method of AsyncTask.
What you can do is
new AsyncTask<Void, Void, boolean>() {
#Override
protected boolean doInBackground(Void... params) {
// Initialize QuickBlox application with credentials.
QBSettings.getInstance().fastConfigInit(Consts.APP_ID, Consts.AUTH_KEY, Consts.AUTH_SECRET);
boolean res = false;
// Authorize application
QBAuth.createSession(new QBCallback() {
#Override public void onComplete(Result result) {}
#Override
public void onComplete(Result result, Object context) {
if (result.isSuccess()) {
//showMainScreen();
res = true
}
//else {
// print errors that came from server
//Toast.makeText(getBaseContext(), result.getErrors().get(0), //Toast.LENGTH_SHORT).show();
//progressBar.setVisibility(View.INVISIBLE);
//}
}
}, QBQueries.QB_QUERY_AUTHORIZE_APP);
return res;
}
protected void onPostExecute(boolean result) {
if(result) {
showMainScreen();
} else {
Toast.makeText(getBaseContext(), result.getErrors().get(0), Toast.LENGTH_SHORT).show();
progressBar.setVisibility(View.INVISIBLE);
}
}
}.execute();
You don't need to use AsyncTasks, because all operations already perform in background.
And also this one
QBAuth.createSession(new QBCallback() {
it performs request in background to QB and call callback in Main thread.
Could you explain what 'connection timeout error' you got.
Is there anything in log?
in the past few days I have been trying to figure something but had no luck, I am developing an android game, I have 3 packages for now each with its own purpose:
1 - package for GUI classes.
2 - package that has classes communicates with my wcf service (login/pass DB)
3 - package that holds my asynchronous classes/workers (like a bridge between GUI and SERVICE)
I am not sure if this is even the right approach when it comes to android/java game development, but what I want to achieve is a simple registeration/login in the GUI and when the user is done registering or logining, while the gui talks to the service through the "bridge", a message is displayed for the user like a dialog saying "registering" or "loging in".
Now I would like to hear tips/feedback from more experienced programmers, on how to acomplish this, and if this is the right aproach, and most importantly some examples for this specific case would be really helpfull, I tried to work with the asynctask but I couldn't figure out how to communicate between these 3 seperate packages and return the result from the service back to the gui through the async task.
Take a look at this
public class FindEventsActivity extends Activity {
ProgressDialog pd;
// lots of other code up here
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.clickete);
pd = new ProgressDialog(this);
pd.setMessage("loading");
findViewById(R.id.clickLayout).setOnClickListener(
new OnClickListener() {
#Override
public void onClick(View v) {
new LongOperation().execute("");
pd.show();
}
});
}
private class LongOperation extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
for (int i = 0; i < 15; i++) {
try {
Thread.sleep(1000); // Simulates your intensive work
// Update your progress if you want
this.publishProgress();
} catch (InterruptedException e) {
return "Failed";
}
}
return "Executed";
}
#Override
protected void onPostExecute(String result) {
// Handle fail or success accordingly
pd.dismiss();
}
#Override
protected void onPreExecute() {
}
#Override
protected void onProgressUpdate(Void... values) {
// Update UI according to your progress
}
}
}
Hope this helps and enjoy your work
How do i make sure that the async tasks finishes before i run certain tasks. I need to use a variable AFTER the async tasks changes the value of that variable. If i run the code before async is done running then im screwed. any help? im obviously new to async tasks. If you look at my code im probably not using onPostExecute() as it was intended so advice would be helpful. My initial thought was to keep adding things to the async task but im thinking that this is just bad practice since i have tons of things that must be run in series. Basically, what i think it boils down to is: how do i make sure that the tasks in the UI thread dont start to run before my async task has finished.
public class MainActivity extends MapActivity {
myJSONmap;
public void onCreate(Bundle savedInstanceState) {
new AsyncStuff().execute();
locatePlace(myJSONmap);
class AsyncStuff extends AsyncTask<Void, Integer, JSONObject> {
#Override
protected JSONObject doInBackground(Void... params) {
jObject = GooglePlacesStuff.getTheJSON(formatedURL);
return null;
}
#Override
protected void onPostExecute(JSONObject result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
myJSONmap = JSONextractor.getJSONHMArrayL(jObject); // getting the parsed data from the JSON object.
//the arraylist contains a hashmap of all the relevant data from the google website.
}
}
You probably want to read more about AsyncTask on Android Developer
http://developer.android.com/intl/es/reference/android/os/AsyncTask.html
About tips, my personal choice is to pass a Boolean to onPostExecute. That way you can evaluate if the doInBackground was succesful, an then figure out what to do (Error message or update the layout).
Keep in mind that in onPostExecute method ideally should only make the screen update, assuming you have the data ok. In your example, why not include the
myJSONmap = JSONextractor.getJSONHMArrayL(jObject);
on the doInBackground? And then call
locatePlace(myJSONmap);
Like this:
class MyAsyncTask extends AsyncTask<Void, Void, Boolean> {
String errorMsg;
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Integer doInBackground(Void... v) {
try{
jObject = GooglePlacesStuff.getTheJSON(formatedURL);
myJSONmap = JSONextractor.getJSONHMArrayL(jObject);
//do stuff
return true;
} catch (JSONException e){
errorMsg="Something wrong in the json";
return false;
}
}
#Override
protected void onPostExecute(Boolean success) {
if(success){
locatePlace(myJSONmap);
//update layout
} else {
//show error
}
}
}
You can ue below code to execute async task -
MyAsyncTask_a asyncTask_a = new MyAsyncTask_a();
asyncTask_a.execute();
Once doInBackground() task is finished then only control will go to postExecute().
You can't perform any UI operations in doInBackground , but you can do so in preExecute() and postExecute().
class MyAsyncTask_a extends AsyncTask<Void, Void, Integer> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Integer doInBackground(Void... arg0) {
// TODO Auto-generated method stub
return 1;
}
#Override
protected void onPostExecute(Integer result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
}
}
Hope this will help you.
I'm writing an app that at many points will attempt to retrieve account information from a website. I'd like to write a single function ("getAccount()") to do the following:
Show a ProgressDialog
Make the call to the website
Wait for a response
Clear the ProgressDialog
Return control to the calling function after the first four steps are done
I'm not having a problem with getting the data from the page; the problem I have is with the whole "show dialog / wait for completion / return control to the calling function" portion. Either the ProgressDialog doesn't show at all, or the function returns to the caller immediately after making the data request from the site, without giving it enough time to retrieve the data.
Any help would be most appreciated.
EDIT: I'm adding a bit of code below for what I have with AsyncTask. Notice that I have the line MsgBox("done") inside grabURL(); this is simply a Toast call. When I run this code, "done" pops up while the HTTP request is still being made. This MsgBox line only exists so I can see if grabURL is properly waiting for GrabURL to finish (which it isn't).
public void grabURL() {
new GrabURL().execute();
MsgBox("done");
}
private class GrabURL extends AsyncTask<String, Void, Void> {
private ProgressDialog Dialog = new ProgressDialog(MyContext);
protected void onPreExecute() {
Dialog.setTitle("Retrieving Account");
Dialog.setMessage("We're retrieving your account information. Please wait...");
Dialog.show();
}
protected Void doInBackground(String... urls) {
try {
// Get account info from the website
String resp = GetPage(ThePage); // I have this classed out elsewhere
// Some other code that massages the data
AccountRetrievalSuccess = true;
} catch (Exception e) {
AccountRetrievalSuccess = false;
}
return null;
}
protected void onPostExecute(Void unused) {
Dialog.dismiss();
}
}
The message box done appears because AsyncTask is using a separate thread(s) to run doInBackground. The call to execute does NOT block. You could move message box done to onPostExecute following the call to dismiss. Tip. You may want to call progress.cancel in onPause or you may get unwanted behaviour on orientation change. Finally, if you are retrieving info in doInBackground, consider returning the info in doInBackground. The info will be passed to onPostExecute. So if the info is object MyInfo consider:
private class GrabURL extends AsyncTask<String, Void, MyInfo> {
Can't say for sure without seeing some code but sounds like you are making a asynchronous call to the website when you want to make a synchronous call (which will block and wait for return data) to the website instead.
You want to use an AsyncTask, generate a non-user-cancellable ProgressDialog in the onPreExecute, do your work in doInBackground, and dismiss it in onPostExecute.
Something like this:
public class MyApp extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// blah blah blah
URL url;
try
{
url = new URL("http://example.com");
new MyTask().execute(url);
}
catch (MalformedURLException e)
{
}
}
protected void doSomeStuff()
{
// stuff to do after the asynctask is done
}
protected void throwAWobbly()
{
// stuff to do if you didn't get the data
}
// inner class to do the data getting off the UI thread,
// so android doesn't "not responding" kill you
private class MyTask extends AsyncTask<URL, Void, Boolean>
{
private ProgressDialog dialog;
private boolean gotData = false;
protected void onPreExecute()
{
// create a progress dialog
dialog = ProgressDialog.show(MyApp.this, "",
"Doing stuff. Please wait...", false, false);
}
protected Boolean doInBackground(URL... urls)
{
// get your data in here!
return gotData;
}
protected void onPostExecute(Boolean result)
{
// get rid of the progress dialog
dialog.dismiss();
if (true == result)
{
// got all data!
doSomeStuff();
}
else
{
// oops!
throwAWobbly();
}
}
}
}