Android :: Sync Between Local Service With Thread And Activity
Jun 1, 2010
I'm trying to think of a way on how to sync in between a local service and the main activity.
The local service has,
A thread with a socket connection that could receive data at any time.
A list/array with data.
At any time the socket could receive data and add it to the list.
The activity needs to display this data. So when the activity starts up it needs to attach or start the local service and fetch the list. It also needs to be notified if the list is updated.
I think I would need to sync my list somehow so the local service does not add a new entry to it while the activity fetches the list when connecting to the service.
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May 2, 2010
I've configured local service under some app i wanna know how could i invoke methods on the activity, through the service in a synchronous way for example the service invoke a method inthe activity and waiting for for result(synchronous) from it.
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Oct 6, 2010
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 ?
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Jun 24, 2010
HTo 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?
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Feb 22, 2009
Starting from the example ServiceStartArguments.java of the "API demos", the service "ServiceStartArguments" is creating a new Handler object (ServiceHandler) which does all the work in a separate thread. Once that work is completed, how can I tell other components that my work is finished, and also provide data (that resulted from the work) to them?
I tried something like startActivity(intent_transferred_via_msg) which does not work, I'll get an exception because I call it "outside of the service", which is technically true.
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Sep 13, 2010
I'm trying to create a program with a service that runs every 10 seconds, puts the camera preview, taking a picture and then leaving the user to continue his work (closing down). Currently I have two problems:
1. After I'm taking the picture, the preview still there. There's no function like close() to return to the previous activity. How can I return to the previous activity?
2. I'm trying to run the above described activity from the run() function (from the timer class that execute the run() function every 10 seconds). When I do that, a runtime exception is raised. But when I start the above described activity from a button clicked (not from the timer) it works fine.
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Jun 12, 2010
In 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?
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Oct 5, 2010
can someone please help me? I would like to write a program which uses a service to periodically update a text view on an activity. I do this by having ActivityA with a 2 buttons to start/stop my service. In the service I run a timer which triggers every second. From here I need to have this launch and update a text view on ActivityB which at present is just a counter value.I'm sure there are likely better ways to do this, such as using only one activity, maybe using a thread but the main design consideration is to have the service running even if my activity is destoyed (the counter value would instead go trigger some alarm or file write instead of a text view update). Sorry for rambling. I find the android developer resources offer too many solutions!
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May 28, 2010
A new question about android and services. Currently I'm developing a App that should send images to a server. It should also be possible to send more images parallel. I made a service that creates for every image a new image. The activity can bind to that service and gather information about the progress. I want to show the current status for every image in a notification (and when the user clicks a notification, an activity with the progress for that image should be shown). But I get several problems with that approach. There are errors with binding, the notification pending event starts the activity completely new, so I lose information about currently sending images and so on. How I could design in a appropriate way.
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Jul 21, 2010
When you do a Thread.currentThread().getId(), is the resulting thread id scoped per process or scoped to the current Activity/Service?
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Nov 9, 2010
I'm confused about whether I need to run my service in a separate process. What are the advantages / disadvantages of each?For reference I'm trying to create an App that uses a service to play [streaming] audio in the background. So which one is better for my use case?
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Sep 30, 2009
i have an app that binds to a local service.I want to add a desktop widget that binds to the same service. does my service have to be a remote service or can it still be local?if it can still be local, how can I get at the local binder?
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Nov 20, 2010
what 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.
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Jul 16, 2010
I don't see the point of using a local service in Android. If I want to do backgound stuff, I can create a thread and use Handlers.
Creating a local service is a big headache, you have to mess with Binders, worry about the start/stop/bind/unbind lifecycle, etc.
What does a local service get me that a thread doesn't ?
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Oct 5, 2009
I am very new beginner, and I am designing a small application as below.
- After a user starts the application, he/she can click the start button to start a background task. (e.g. retrieving the news headlines periodically, then do something...)
- Even after the user quits the application, the background task still running.
- To stop the background task, the user needs to run the application again, and clicks the stop button to stop the background task.
In the above scenario, what API should I use ? (Local Service Binding ? Remote Service Binding ? Handler ?)
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Jun 11, 2010
I'm starting a service in my application using startService.
I do not want to use bindService as I want to handle the service life time myself.
How can I get an instance to the service started if I do not use bindService? I want to be able to get a handler I've created in the service class to post messages from the activity.
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Sep 9, 2009
I have the following base activity. code...
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May 31, 2010
I don't need a strict code related answer I just need somebody to tell me what I am missing.My application has to retrieve from a web service (xmlrpc) the positions of some users I know and update their position on a MapView.So I decided to use a Service and an Activity extending MapActivity to show results.
I thought about two solutions:
I ) start the service and make it ask every minute for these positions and send them to the activity as a bundle via intent. (This didn't work out well, since once shown I couldn't find a method to let the activity continue refresh itself until she stop receiving intents+data from the service)
II ) Incorporate a thread within the activity which starts the service via context.startService(...) every minute. And the MapUI refresh itself once the service send back an intent and stop itself. (Maybe I will fall in the same problem category as before I haven't tryied yet).
I am also giving directions (via maps.google ws) in this way I'd like to refresh only users positions on the map and save the route.What Am I missing do you have any suggestions? related to activities/services internal mechanics, don't know launch modes, use broadcast receivers or intent filters?
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May 16, 2010
An application I'm building uses a local Service for downloading files from the web to the phone's SD card. In this app users can browse lists of books, and read them while online. A user can also download a pdf copy of a book for offline viewing. To handle downloads I'm using a locally bound Service. I do not want this Service to run all the time, only when downloading files. So that the Service can shut itself down when its tasks are complete, I am not binding to the service, rather I'm sending an "enqueue for download" command through the Intent passed to Context.startService.
Books available for download are shown in a list. A user can choose to download a book by clicking on its row in the list. On download, I need to show download progress using a ProgressBar on the actual book list row. I need to also show, on the rows, if a book is enqueued for download, or if its download has completed or failed. The books can be shown in different activities throughout the application--in search, or in the user's list of favorite books, for example. When the books are shown in different places, these are not the same objects, but they are uniquely identified by their bookId...............
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Sep 30, 2010
How do I check whether the local service inside my application is running?
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Sep 15, 2010
My application has the following components: 2 Activities A Service and a BroadcastReceiver
Whenever the user updates the system time, my broadcast receiver receives the Intent.ACTION_TIME_CHANGED. Now when this happens I want to reschedule a Handler in my Service. How do I bind to a Service within my BroadcastReceiver?
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Nov 20, 2010
I have a local Service to which multiple activites needs to bind. In the first launched Activity, bindService returns true and onServiceConnected is called. But in any additionally launched activites bindService returns false, and I can't get a reference to my Service.
How can multiple activities simultaneously be connected to a local Service?
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May 6, 2010
Essentially my problem is this, I open my Activity. It binds to a local service that "appears" to be connected. I get a force close when I press the back button:
"IllegalArgumentException: Service not registered" when unbind is called in my onPause method...
public void onPause() { super.onPause(); if (isFinishing()) {
if (mConnection != null){ Log.i(TAG,"onPause, mConnection" + mConnection.toString());
mDbS.unbindService(mConnection); }else { Log.i(TAG,"mConnection is null");
} The service is bound in onCreate // bind to our sdCard database using our Service Connection
mServiceIntent = new Intent(this,DatabaseService.class);
if(bindService(mServiceIntent, mConnection, Context.BIND_AUTO_CREATE)){
Log.e(TAG, "service bound"); }else{ Log.e(TAG, "service not bound");
} bindService is returning true.
My Service connection is as follows. onServiceConnected is called and goes to completion. onService Disconnected is never called (presumably because my service is in same process)
private ServiceConnection mConnection = new ServiceConnection() {
public final String TAG = "LoadView.ServiceConnection"; //$NON- NLS-1$
public void onServiceConnected(ComponentName className, IBinder service) {
mDbS = ((LocalBinder<DatabaseService>) service).getService(); .....
stuff not relevant.... Log.i(TAG, "finished onServiceConnected");
//$NON-NLS-1$ } public void onServiceDisconnected(ComponentName className) {
Log.e(TAG, "onServiceDisconnectedCalled"); //$NON-NLS-1$ } };
The only thing I do a little different is that I don't use an inner class in my service for the Binder object - I use a separate class. This is mostly because I have several databases and wanted code I could reuse and set up simply rather than worry about all the ins and outs and memory leak issues.
import android.os.Binder; import android.util.Log;
public class LocalBinder<S> extends Binder { private String TAG = "LocalBinder";
private S mService; @SuppressWarnings("unused") private LocalBinder() {
} public LocalBinder(S service){ mService = service;
} public S getService() { return mService;
} public void finalize(){ mService = null;
try { //TODO reinstate this after Issue 8046 is resolved
//super.finalize(); } catch (Throwable e) { Log.e(TAG,"Unable to finalize Binder");
} } }
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Jul 2, 2013
I have an android app that must connect to my local webservice with soap but I cant seem to get it working. This is the code I have.
[HIGH]public void Hello()
{
String SOAP_ACTION = "http://tempuri.org/Hello";
String METHOD_NAME = "Hello";
String NAMESPACE = "http://tempuri.org/";
String URL = "http://10.0.2.2/MainService/MainService.asmx";
[Code]...
All this does is catch an exception with the message "Null". Note that I am not an android developer, this is my very first project.
I did the same thing with Netbeans and regular Java and it works perfectly.
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Jan 18, 2010
I 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.
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Jun 17, 2010
Would it be there noticeable speed improvement if I would create local references to needed view elements (e.g. EditText or Button) in my activity (in onCreate()) and use them for accessing needed elements or it does not much matter if I always use findViewById() when I need to access some particular element?
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Feb 14, 2009
I am having trouble running my application as every time i try to run it the simulator gives me a an error.
I looked through the Documentation but I couldn't find anything on user created classes.
CODE:.................
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May 26, 2009
I 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?
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Dec 16, 2009
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.
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Nov 14, 2010
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.
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