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?
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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...
View 8 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 want to download some data from internet.It should not block main UI thread. I know both thread and service can handle the work. What is the difference between them?
View 4 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 Relatedwhat I'm trying to do here is implement something like a peer-to-peer client. Being that, it will start a client thread and a server thread.I know Services themselves run in the main GUI thread, so I'll have to start a couple of independent threads (or Asynctasks?) for each server and client. The only thing I'm not so sure about is if I'll better have 1 Service starting 2 threads, or maybe 2 services, each one of them starting their own thread.
View 2 Replies View RelatedWhat is the difference when a class extend from Handler and Thread?
As described in developer.android.com
...
Each Handler instance is associated with a single thread and that thread's message queue.
...
Does the thread has no message queue ?
Any benefit for a class extend from Handler?
Since I've bought the hero I have not installed a task manager and I would see it getting a little more laggy or choppy. So I decided to install task killer, my phone is back to being the way it was when I first got it. I know the rumors and all but I do think task manager is the way to go from 90mp free to 180mb.
View 10 Replies View RelatedI'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 RelatedI am developing an app and get confused about the idea of Service and Content Provider in Android. In practice, what will be the difference between them? Content Provider is a facade and it defines a way to share data among applications. You many attach a local database to your app or create Content Provider mapped to a universal database so that all the application on the same device can share it. Service is long running processes that need to be decoupled from main activity. It has local and remote service. local service is like the local database, and remote service is like Content Provider sharing the database info.
What My App is doing? downloads info. from multiple internet resource in the background (I suppose this will be Service) and store the info. into database, and multiple applications will need to retrieve the data, format them and output them to user (I guess it will be a Content Provider). What will be the fine line between Service and Content Provider? Newbie in Android
I am currently writing my first Android application and I keep running into references to background and foreground services. Since I intend on using a service in my application I was hoping to get a clarification between the two and how they are used.
View 1 Replies View RelatedIs there any difference between what happens when you use a Task Killer App to kill an app vs. what happens when the Android OS kills an app due to scarce resources? The Android SDK says that the Application.onTerminate() method isn't called when the OS kills an app due to scarce resources. So it sounds like the OS doesn't cleanly close apps and that it does exactly what the much-debated task killers do. If they do the same thing, then task killers don't do any more harm than the OS itself, right?
View 3 Replies View RelatedI wanted to know what is the difference between Context.startService(intent) and startService(intent) and does it matter which one is used?
View 1 Replies View RelatedI am new to Java and Android.I would like to retrieve remote data and display it within my activity. To prevent tying up to UI, I understand that I can do this in another thread. (I thought I could just-as-well fetch this remote data from within a service, but that appears to tie up the UI thread also). So now I'm beginning to think I need to either run the logic from a new thread within a service, or run a service within a new thread. But which? I have found many examples online of running new threads or services, but I have yet to find an example of both at the same time.
View 7 Replies View RelatedIn Virgil Dobjanschi's talk, "Developing Android REST client applications" (link here), he said a few things that took me by surprise. Including:
Don't run http queries in threads spawned by your activities. Instead, communicate with a service to do them, and store the information in a ContentProvider.
Use a ContentObserver to be notified of changes.
Always perform long running tasks in a Service, never in your Activity.
Stop your Service when you're done with it.
I understand that he was talking about a REST API, but I'm trying to make it fit with some other ideas I've had for apps. One of APIs I've been using uses long-polling for their chat interface. There is a loop http queries, most of which will time out. This means that, as long as the app hasn't been killed by the OS, or the user hasn't specifically turned off the chat feature, I'll never be done with the Service, and it will stay open forever. This seems less than optimal.
Long question short:
For a chat application that uses long polling to simulate push and immediate response, is it still best practice to use a Service to perform the HTTP queries, and store the information in a ContentProvider?
I have an application which requires networking service. I took on LWUIT4IO and adjusted it to my needs so now i have a network queue that can run one or more network threads.Now, my application is based on single root activity that spawns other child activities as needed (it's a reservation center for vacations, car rental etc.. each in it's own activity). The network is common to all and should be used by all activities. the network thread requires, basically, a callback to notify it's finished and return the result (input stream or byte array) .At first i thought that i should use a service instead of a singleton that will be started in the root activity(the service will also be started in the root activity), however working with a local service is problematic for me: 1. no callbacks which makes me use intents to encapsulate the request esponse in intents time consuming, also since there is not single point of listening (i have to use BroadcastReceivers)i have to add a calling class name or some other identifier so the sender of the request will know it's for him, i think this is also a waste of time and resources since i need only one listener.
i think i CAN use callbacks if i use Binder object to return local instance of my Service and then use the queuing method directly, this is problematic for me as acquiring Binder object is asynchronous and i need it 'on the spot' 3. I thought of using a static instance of the service and null it in onDestroy of the service, but if i use that way, i'm not so sure i need a service... 4. i saw a small answer in stackoverflow about inheriting application and putting whatever member you need there so when you use getApplication you get this instance and then you can retrieve whatever you want, is this even advisable ?
I have two apps that use a service to upload and download files and data. I've noticed that when the service gets very busy, it can cause the UI to block, up to the point that Android shows a "force quit/ wait" popup. In order to avoid that, I run tasks in a service at a lower priority. This way, the service will never cause the UI to hickup. Also, the service stops if the app hasn't been used for a certain number of minutes. I don't want to keep resources if the user isn't using my app.I have found that some of my users run apps that run services permanently at normal priority. Such a service starts at phone switch on, and keeps running indefinitely, downloading vast amounts of data. My policy of being nice to other apps doesn't pay off: these agressive third party services push my service away so it never gets anything done. As one of my users told me, my app has hickups, until he kills the service of this app X, after which my app runs smoothly, snappy, and fast.
My question is, should I be nice to other apps and to the UI in my own app, or should I just run a service and agressively take all resources I need - or don't need? This is one issue where Android is different from iPhone. We can run services, but by doing so, we can cause damage to other peoples apps. Of course, my "question" doesn't require an answer. I'm just curious after what other people think, what your experience here is.
I am developing an Android app and I am doing some heavy work (bringing data from an online web page and parsing it to store in database) in a service. Currently, it is taking about 20+ mins and for this time my UI is stuck. I was thinking of using a thread in service so my UI doesn't get stuck but it is giving error.
View 1 Replies View RelatedI am starting to develop a new app and I am a bit confused about the structure I need to give it.I need to react to broadcast intents, so I placed a broadcast received in the manifest. Every single intent produces an action to be performed. Now the first question: should I start a service (maybe with non_sticky option?) or should I start a thread (or an async task) directly from the broadcast receiver? If I start a service, should I do all the stuff in its body, or should it start a thread. I should do the heavy job in a thread if there are time consuming operations, but what if the gui of my application is just an activity with the options and a button to start the service. What is the point in keeping the main thread busy? Do I risk to be killed for not being responsive? I read here and there that I can update the gui from a background thread. Can I do that even if it is started from a service? The AsyncTask's onProgressUpdate is said to run in the application main thread, but if the application is made of different activities, who tells me which activity is the user looking at while the thread is doing all its long work? The user could change activity in the meanwhile and then the update would be unuseful.I know it's (quite) a lot of questions, but I need to get some clarifications before taking the wrong path.
View 5 Replies View RelatedMy IntentService is blocking my UI thread and I wanted to find out why. So I turned on profiling in the onStartCommand method of the IntentService and turned it off at the end of the onStartMethod. The working being done in between is web access with the Apache HTTP client.According to the profiler, the onStartCommand method of the IntentService is running on the main thread, not in a worker thread. Any idea what could cause this behavior?
View 3 Replies View Relatedi have a little frontend showing a list of items that it will retrieve from a service. I want that service to be started in a separate thread.so the UI is still responding to user interaction while waiting for that service to call a callback method. What is the best way to start the service in a detached thread?
View 6 Replies View RelatedI am a newbie in android and i had a question whether i should use a service or thread for http connection and what will be the advantage of using a service over a thread or viceversa. Please help me out with this.
View 13 Replies View RelatedHTo be able to write "nice" code between my application/activies and a local service I need to understand some basic Android concepts:What I'm wondering is if my application (as in my activities) and my local service is sharing one thread. I.e. when the activities and the local service executes tasks queued are these tasks interleaved in ONE thread thus sharing the thread or does the service has a thread of its own?Also if the local service shares the thread with the activities and the local service makes a direct call (via a callback) to one of the activities (i.e. no post message) is the activity thread "halted" or is the execution of that specific function queued to be executed later anyway?
View 1 Replies View RelatedI have an application that starts on boot using a broadcast receiver, also I have an activity and a process, because the service must run always on the background I am starting the service on it's own process using the android:process manifest tag.The ui is only for presentational needs and I would like the user to be able to run the service even if the activity is not active.when I press the back button or the home button the activity's on destroy method is called and the service although seems its running (it appears on the task manager) its not behaving as supposed, it should connect to the net and send some data but every X time using an timer task but the task never fires so the data are never send.
View 1 Replies View RelatedI need to create a service that runs a piece of code in new thread after (let us say) 10 mins. How can I do that? I have service ready but I don't seem to understand how (if ) to call timer from within thread.
View 3 Replies View RelatedIt is very important that my service stay running until someone with a password stops the service from my UI screen. My app runs great but it is designed to be turned on/off by parents (with a password) on their kids phones. I have managed to make everything work but the problem I'm having is that if the kid uses a task manager to kill my service then my app is useless. I would be grateful to anyone who knows a way to either
1) monitor the service and start it back up automatically if its "killed"
or
2) prevent someone from being able to kill it except from the activity (administration screen) that launched the service. Or both?