I have a simple app and I'm using the AsyncTask to test out a background process, for clearness purposes I've opted to put my AsyncTask in a separate class rather than in an inner class, which where my problems begin, this is my AsyncTask. Code...
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What is the difference between Service, Async Task & Thread. If i am not wrong all of them are used to do some stuff in background. So, how to decide which to use and when?
View 2 Replies View RelatedI've got an Android activity which grabs an RSS feed from a URL, and uses the SAX parser to stick each item from the XML into an array. This all works fine but, as expected, takes a bit of time, so I want to use AsyncActivity to do it in the background. The line items = parser.getItems() works fine - items being the arraylist containing each item from the XML. The problem I'm facing is that on starting the activity, the ProgressDialog which i create in onPreExecute() isn't displayed until after the doInBackground() method has finished. i.e. I get a black screen, a long pause, then a completely populated list with the items in. Why is this happening? Why isn't the UI drawing, the ProgressDialog showing, the parser getting the items and incrementally adding them to the list, then the ProgressDialog dismissing?
View 3 Replies View RelatedI'm writing an Android app. I have a main method, which creates and runs a new Thread using an anonymous inner Runnable class. The run() method, when it's done, calls a method on it's parent class (in the main thread) that calls notifyDataSetChanged() so that the main thread can redraw the new data. This is causing all kinds of trouble (ViewRoot$CalledFromWrongThreadException). The thing is, this method being called from the worker thread is on the class that's created in the UI thread. Shouldn't that be running on the UI thread? Or am I missing something.
View 1 Replies View RelatedI just have a concern about AsycnTask. If i have one activity which starts a async task. Now that activity goes in background and new activity gets opened & visible to us.
So the async task opened by previous activity stops or it still keeps going in background or it pauses or stops ?
I read somewhere (and have observed) that starting threads is slow. I always assumed that AsyncTask created and reused a single thread because it required being started inside the UI thread.The following (anonymized) code is called from a ListAdapter's getView method to load images asynchronously. It works well until the user moves the list quickly, and then it becomes "janky".final File imageFile = new File(getCacheDir().getPath() + "/img/" + p.image);image.setVisibility(View.GONE);view.findViewById(R.id.imageLoading).setVisibility(View.VISIBLE);
(new AsyncTask<Void, Void, Bitmap>() {
@Override
protected Bitmap doInBackground(Void... params) {
try {Bitmap image;
if (!imageFile.exists() || imageFile.length() == 0) {
image = BitmapFactory.decodeStream(new URL(
"http://example.com/images/"
+ p.image).openStream());
image.compress(Bitmap.CompressFormat.JPEG, 85,
new FileOutputStream(imageFile));
image.recycle();
}image = BitmapFactory.decodeFile(imageFile.getPath(),
bitmapOptions);
return image;
} catch (MalformedURLException ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
return null;
} catch (IOException ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
return null;
@Override
protected void onPostExecute(Bitmap image) {
if (view.getTag() != p) // The view was recycled.
return;
view.findViewById(R.id.imageLoading).setVisibility(
View.GONE);
view.findViewById(R.id.image)
.setVisibility(View.VISIBLE);
((ImageView) view.findViewById(R.id.image))
.setImageBitmap(image);
}}).execute();I'm thinking that a queue-based method would work better, but I'm wondering if there is one or if I should attempt to create my own implementation.
I have the following code...
CODE:.................
My mClient get method is a simple HttpClient execute with an output buffer to read the input stream, so it's very trivial. Everytime I execute this task UnknownHostException will be triggered which will in turn call onTaskError on my currect Activity, but I still get a RuntimeException, but I don't see why. Maybe it's because it's late and i've done about 12 hours of writing code so it's something simple I just can't see?
I have been searching for an answer for this for some time now. I have an async task that downloads the database needed for my app, while this is downloading my app cant do anything as all the data it references is in this file, i have the app waiting for the file to be downloaded but i am attempting to show a progress dialog so the user knows something is happening while they wait for this to happen.however nothing shows up i have also tried directly calling ProgressDialog.show in the pre execute and moving this to the calling activity with no luck.
View 2 Replies View RelatedIn Handler, we can pass some data from a background thread to the UI thread like this:
private void someBackgroundThreadOperation() {
final String data = "hello";
handler.post(new Runnable() {
public void run() {
Log.d(TAG, "Message from bg thread: " + data);
}
}
}
If we use the above, we cannot then use Handler.removeCallbacks(Runnable r), because we won't have references to any of the anonymous runnables we created above. We could create a single Runnable instance, and post that to the handler, but it won't allow us to pass any data through:.............
I have two activities:
"a" that spawns thread for generating a dynamic array of values inside public void run() function.
"b", graphics activity that will help me draw rectangular pulses based on array values calculated in activity "a" (calculated in a's thread to be precise).
When I am in thread inside "a", how do I pass values of array to activity "b" and
call activity as well.
activity A
CODE:..........
activity B
CODE:..............
HTC Desire Message app jumps back to top of thread
Since I've installed 2.2 the message app on the desire jumps to the top of a message thread randomly while I'm writing a message meaning I have to scroll to the bottom again. This can be very annoying in thread which I have lots of messages. Any ideas on how to fix this?
I am trying to communicate between two Android applications. Application-A will send message/data to Application-B. After receiving message from Application-A, Application-B will send a reply message to Application-A. Is it possible in Android application? If yes please point me the APIs that can be used to achieve this.
View 3 Replies View RelatedI'm new to Android, and event driven code in general. Rather than embed loads of anonymous event listener classes in my Activity to handle onClick events etc, I defined separate classes to keep the code clean. Then I use them e.g. like this
myButton.setOnClickListener(new MyEventListener());
So, when 'myButton' gets clicked, MyEventListener's onClick method does some stuff.
I wanted to know the best practice for
a) accessing things in my Activity from the event listener. For example to change the text of a label. The onClick event takes a View in, but this is the view for the button that's been clicked, so if the label is NOT a child of my button, I can't use findViewById to get a handle to it. I've modified the constructor to pass in a reference to the label, so that the event has a handle to it but not sure if this is the most elegant way of doing it.
b) Passing information back e.g. when my event fires, I might want to disable some EditText fields. I'm thinking the proper way to do this is probably to dispatch another event from my event listener, that the Activity listens for, and when it sees the event, disables the fields in question. Is that the way to do it in Android?
I'm trying to learn AsyncTask and Thread but Thread first. I am trying to display a Dialog before "DoSomeTask()" but seems like the Dialog always come after DoSomeTask(). Did I do something wrong here?
--- code---
@Override public void onClick(View v) {
// TODO Auto-generated method stub mainProcessing();
DoSomeTask(); } private void mainProcessing() {
Thread thread = new Thread(null, doBackgroundThreadProcessing, "Background");
thread.start(); }
private Runnable doBackgroundThreadProcessing = new Runnable() {
public void run() { backgroundThreadProcessing();
} };
private void backgroundThreadProcessing() {
handler.post(doUpdateGUI);
} private Runnable doUpdateGUI = new Runnable() {
public void run() { updateGUI();
} };
private void updateGUI() {
final ProgressDialog dialog = new ProgressDialog(CloseVault.this);
dialog.setMessage("Please wait...");
dialog.show();
}
When I first got my desire a few weeks ago and joined this forum, i am sure there was a sticky about not using a task killer app. Can someone please link me to it. Been trying to search it out with no look. Think it was by one of the mods. I was new to android at the time, but now I would like to know why task killing is a bad idea. I must have shed loads running in the background.
View 12 Replies View RelatedSometimes when I receive messages it makes the notification sound and will show message in notification bar but the text of the message will not appear in the text thread. Used to happen every once in a while, now doing it multiple times a day. I use Handcent but I doubt that is the problem because the messages dont show up in the regular messaging either. Just want to see if i am alone with this problem.
View 8 Replies View RelatedNot sure if this is a common problem, but essentially, in the bundled 'Messages' application for the HTC Legend, the text messages are saved as a thread as standard. But today, for some bizarre reason, when I open a message thread, it opens at the oldest message, whereas before, it would open at the most recent message. I've looked around in the settings, turned my phone on and off, cleared the data, but still can't get it to revert, it's quite annoying to scroll through hundreds of messages to get to the most recent SMS.
View 1 Replies View RelatedI am using RunningTaskInfo.topActivity.getClassName() to determine the class name of the activity being viewed by the user. If the top activity is an sms message (the user is texting) then I want to determine either the thread id of the open message or the contact name/ number, either will work! I am able to determine if a message is open by comparing the class name.unningTaskInfo.topActivity.getClassName().equals("com.android.mms.ui.ComposeMessageActivity") which returns true/false. When it is true I need to get the above information from this "compose message". Any ideas on how I can get this kind of information from an Android OS activity (an sms message)?
View 3 Replies View Relatedis there an app to copy a complete text thread and email?
View 1 Replies View RelatedMy application launches a thread to query the web for some data. I want to display a Toast message when nothing is found, but my application always crashes. I've tried using the application Context from within the thread, like so: Toast.makeText(getApplicationContext(), "testttt", Toast.LENGTH_LONG).show(); I've also tried creating a Runnable with the Toast call and calling runOnUiThread(runnable) from the Thread (the Toast call in this runnable uses the Activity as the first parameter). Does anyone have any ideas on how to accomplish this?
View 3 Replies View RelatedI am queuing up a bunch of runnables into a thread via a Handler.post(). I would like the ability to send a note to that thread that it should pause. By pause I mean, finish the runnable or message you are currently working on, but don't go to the next message or runnable in your message queue until I tell you to continue.
View 2 Replies View RelatedIs there a way to tell when my task gets put on the back of the UI stack (user pressed "home" say?) I have some resources I'd like to free when not foregrounded. The lifecycle routines seem dicey to use to try and infer this. The "home" key does not seem to be passed to onKeyDown(), and moveTaskToBack() is never called by the system so I can hook it. I can poll the ActivityManager for running activities with my task id, but hard to find a good time to call this.
View 5 Replies View RelatedI have a problem handling messages in a Thread. My run-method looks like this The problem is that the run-method logs "id from message: null" though "message ID" has a value in the Log-statement. Why does the message "lose" it's data when being send to the thread? Has it something to do with the notify?
View 1 Replies View RelatedI have an app with a two threads - main and data loader. When data loader finishes it posts a Runnable object to the main thread (as described in the DevGuide), but it never gets delivered and run. Here's the basic code:
class MyApp extends Application{
public void onCreate()
{LoaderThread t = new LoaderThread();
t.start(); }
private class LoaderThread extends Thread {
public void run()
{ SystemClock.sleep(2000);
boolean res = m_handler.post(m_runnable);
if(res)
Log.d(TAG, "Posted Runnable"); } ............
I'm writing unit tests for a ListActivity in Android that uses a handler to update a ListAdapter. While my activity works in the Android emulator, running the same code in a unit test doesn't update my adapter: calls to sendEmptyMessage do not call handleMessage in my activity's Handler. How do I get my ActivityUnitTestCase to sync with the MessageQueue thread and call my Handler?
View 2 Replies View RelatedI'm having trouble to figure out how to bring the paused Task back to foreground. As far as I understood, when I click HOME button while a task is running, the task will be paused (onPaused() of the current top-level activity will be called,right?). I think there might be a way to bring this paused task back to foreground since the task is still ALIVE, but I don't know how. Do I have to put some more codes in the activity (I mean the one that is paused)?
View 5 Replies View RelatedI have a service from which a start a new thread. This new thread will communicate with a TCP server using socket. What is the best way to send the data received from TCP server back to the service? Handlers or something else?
View 1 Replies View RelatedI am using an Executor [fixed thread pool] with my own ThreadFactory that adds a Looper:
CODE:...............
I am running a thread that makes network requests but if the network fails I would like a dialog message to be displayed to the user. This process is rather involving since it requires making AND displaying the request in the UI thread. I can wait for the user's response to the dialog by simply adding a Loop to the network thread and wait for a message to be send from the UI thread. This allows me to encapsulate the network requests in a while(tryAgain) thread. All works well except when the Looper.loop() method is called the second time (after a second network error dialog is displayed) and a message is sent by the dialog (in the UI thread) to the network thread's handler:
CODE:.............
In the AlertDialog instance is an OnClickListener:
CODE:...............
I've checked that the thread is still active with handler.getLooper().getThread().isAlive() which always returns true but it still gives me "sending message to a Handler on a dead thread". How is it that the Message/Handler has decided that the thread is dead? Shouldn't it rely on the .isAlive() method? In the end I am trying to avoid replicating the thread management build into the Android OS .
I show to user a list of categories, he must choose one.
How to force the user to choose before pressing back?
Am currently running the deFrost FroYo ROM. Everything's fantastic, except...whenever I'm viewing a text message thread, it's slow to scroll through previous messages. Frustratingly slow. Is this a common issue with the deFrost ROM? Or is there something I can change / configure to resolve this?
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