Android :: Call AsyncTask Methods From Another Class - Service - Callbacks?
Jun 1, 2010
I was wondering if it's possible to call specific methods defined within the AsynTask class from another class and/or service ?
In my specific case I have a Service playing some sounds, but the sound is selected from a List with available sounds...
When a sounds is selected it is downloaded from my home server, this takes some time (not much, let's say around the 3-4 seconds, the sounds/effects aren't big in size)...
So my problem at the moment is that I have a service to play those sounds, and when I select one I wanted to show a progressdialog... The way (if I understood correctly) is to use an AsyncTask, but the only thing the AsyncTask will do is telling my Service to play a specific sound from my server... So there is no "callback" from the service to the Asynctask...
How can I call a running AsyncTask, which sits in another class, and tell him all work is done and thus he can stop showing the ProgressDialog ? Or am I over-engineering it and there are other ways ?
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Jun 22, 2010
Hi, custom classes which are part of a framework, so nothing graphical. One of those (singleton) classes is a Logging class which send logs to my server. I noticed that even though I can call the classes methods in my service it actually won't be logging anything... In my specific example it's osmething like : Logger.getInstance().log("Whatever I want to Log"); Obviously the getInstance is a static method so it can be accessed from anywhere within my project right away.. I was wondering though why this method for example isn't getting called ? Also how do I debug a Service ? Btw I am using of IPC from one of my Activities which gets bound to the service and can start/stop the music for example...
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May 1, 2010
Everything is in the title.
On the official documentations it is stated that Note that services, like other application objects, run in the main thread of their hosting process and AsyncTask only works if it is executed in the UIThread.
So is it possible to use AsyncTask in a Service class? code...
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Apr 27, 2009
Is it possible to call methods of a Activity from service. I am running a thread from a service and i listening to some external event from that thread. I am not able to call methods from that thread. Is there any way to call methods from a thread.
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Dec 7, 2009
I made two applications. One for an activity receiving user input, the other for a background service. In the service package, I create two files (startSensorBroadReceiver.java, remoteService.java). StartSensorBroadReceiver will receiver an intent from activity application and call method inside of the service. There is no erron in the codes but I can not excute what is want. I meet a message like this "The application ServiceExample has stopped unexpectedly. Please try again." could you let me know. what is wrong? and how I can call service methods from broadcastReceiver?
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May 28, 2010
I'm developing a GPS tracking software on android. I need IPC to control the service from different activities. So I decide to develop a remote service with AIDL.This wasn't a big problem but now it's always running into the methods of the interface and not into those of my service class. Maybe someone could help me?If i now try to call a method from an activity for example start(trackId) nothing happens. The binding is OK. When debugging it always runs into the startTracking() in the generated ITrackingServiceRemote.java file and not into my TrackingService class. Where is the problem? I can't find anything wrong.
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Nov 3, 2010
i hav two classes...both classes are extends activity.. i need call other class method on main class on android development..its urgent..please.. i done something like subclass sub = new subclass()...its not work..
In 1st activity class
package org.me.intent_testing;
import android.app.Activity; import android.os.Bundle; import android.widget.; import android.view.; import android.content.Intent;
/** * * @author pavankumar */
public class FirstActivity extends Activity {................
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Sep 18, 2010
I have an android application. Based on the current geo location of user, I want to fetch some remote data in background and store it. My implementation is: At specific interval a alarm fires up my service. Service uses an anonymous class to query current location and registers a locationListener callback. On call of onLocationChanged() I initiate the remote data fetch from server.
However once my service is done registering the location listener using anonymos class, it returns as expected; as it doesn't wait for callback to happen before finishing. Since callback takes some time and makes a call when service has already returned, it throws an error saying: java.lang.RuntimeException: Handler{43e82510} sending message to a Handler on a dead thread
Which is quite understandable. One quick workaround for me now is that I can use getLastKnownLocation from locationManager as that doesn't respond back by callback; but what if I do want the latest location right now, in a service and not activity? How can I wait for callback to happen and stop my service from returning.
Also, at what point does lastKnownlocation gets updated? Everytime GPS registers a new location; does it update it? What I want to know is that if it's not latest can it still be closed to latest? As I didn't see an option in android emulator to configure the time period between subsequent updates.
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Jul 7, 2010
I'm working on a service for my application whose purpose is to allow easy access to various web services we are running. The service is used to maintain a login state across any applications that want to use it so the user only has to log in once when the service is first started.
What is the best way to go about making the service run asynchronously and call back to the application when it is finished. Currently I am using static classes that extend Thread such as
CODE:.....
And to make it easy to call
CODE:....................
But these functions can only be called by my own application. I want anyone to be able to make a one or two line function call and be able to handle the response easily, preferably in a simple callback method.
I figure it has to be done using Intents to start the Threads, but if I do that I can't pass a callback.
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Nov 3, 2010
i hav two classes...both classes are extends activity.. i need call other class method on main class on android development..its urgent..please.. i done something like subclass sub = new subclass()...its not work..
package org.me.intent_testing;
import android.app.Activity;
import android.os.Bundle;
import android.widget.;
import android.view.;
import android.content.Intent;...........
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Jul 27, 2010
What I want is just to have the AsyncTaskTask showing a progressbar an external class. To do this I am passing the context as you can see in the main class. But whatever I try I get NullPointerException.
Working code examples.
Using Android 2.2 by the way.
main:
CODE:............
Update:
I have a follow up question: Using the above code, is it possible to return a value from the onPostExecute method back to the main class, somehow? (Sorry about beeing noobish)
I have tried something like this:
String result = new AsyncClass(this).execute();
and then a method that return back a string. But I can't do that because i got:
Type mismatch: cannot convert from AsyncTask<String,Void,Void> to String
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Aug 17, 2010
I currently have an app that has many activities and needs to have a way of maintaining state between these activities.
I use the Application class to do this, declaring my global variables and using getters and setters to interact with my activities.
I was hoping to place a few custom methods in there, so that when I want to do a common task like, for instance, display an error message, I can declare the method in my application class and call it from any activity that uses it
EscarApplication application = (EscarApplication) this.getApplication();
EscarApplication being the name of my application class above.
I have tried to include this method in my application class:
CODE:.....
In the hope that I can call this method from activity without having to redeclare it, but when I call it using something like below I get an null pointer exception:
Visit.this.application.showError("Update error", "An error has occurred while trying to communicate with the server");
Visit being the name of my current activity above.
Should this work, or can I only use getters and setters to change global vars in an Application Class.
EDIT Stack Trace:
CODE:...............
The dialog is declared as such in the application class:AlertDialog alertDialog;
Created in that same class:alertDialog = new AlertDialog.Builder(this).create();
And the method to call it in that class is as follows:
CODE:.............
And finally, it is called from an activity like so:
CODE:........................
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Feb 5, 2010
I am trying to create HTTP connection using AsyncTask class.
Is it possible to create HTTP connection ?
Can you suggest sample source code?
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Oct 8, 2010
I have just started android. I just want to know that how can i call activity class from other java class. i just want to pass class object to activity class.
public class GsonParser extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
MagazineThread thread=new MagazineThread();
thread.start();
}
public GsonParser(JsonMagazineParser Obj)
{
}
}
and i am just doing like from other class. GsonParser obj=new GsonParser(this);passing obj to activity class.how can i achieve that.
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Jun 26, 2010
I have a service, that requests another class, which launches an AsyncTask
Service->Weather Class->Execute Method->Asynctask->Execute
this is launched in the service by
new Weather(this).execute(); // the execute is a method of the class, not of the AsyncTask
how do I detect in Service that the AsyncTask finished so I can call stopSelf?
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Aug 12, 2010
I have a Service that creates AsyncTasks for downloading files. In activities, we create Runnables or Threads that we pass to Activity.runOnUiThread(). I can't access that method from a service, so how do I use AsyncTask correctly, (do heavy work without blocking the UI Thread)?
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Oct 10, 2010
So I'm writing an Android app which uses a large c++ library. I have everything working so that the java app can call the c++ delegation methods, but I'm finding myself wishing I could log messages from c++ to the Android log. This is easy from java, but I'm at a loss as to how to call a java method from c++. My searches found methods for opening a jvm from c++, which is not at all what I want to do. Ideally, I'd like to pass a log method pointer to c++, which could then be used whenever I wanted. Of course, java doesn't support method pointers.
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Oct 12, 2010
I have an activity which starts a service. In the service there is a network lookup in an AsyncTask. Results from the lookup are saved to a database.
The activity queries to database and shows the newest entries. But at the very first run the database is empty, so there is nothing to show. In this case I would like to show a progress dialog to the user while the network lookup is taking place. I would like to dismiss the progress dialog when the first lookup is finished.
Is there a way to access the progress dialog created in the activity from the service? Or how to do it?
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Apr 8, 2013
I need a endless loop/while/for.How to do this in a AsyncTask or Service?
[HIGH]public class Back extends AsyncTask<Void, Void, Void>{
@Override
protected Void doInBackground(Void... params) {
handler.postDelayed(new B1(), 2000);
handler.postDelayed(new B2(), 3000);
return null;
}
}[/HIGH]
I want to make my handler endless loop/while/for.
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Jul 21, 2010
I am curious whether the AIDL only serves for inter-process communication between several Android apps on the same device, or AIDL provides much wider functionality. Let's say I have a Java application running on some server, is it possible to remotely call methods on that server through AIDL from an Android phone?If yes, do I need some extra libraries on the server-side Java application?
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Jul 28, 2010
I'm trying to figure out the correct way to create an AsyncTask to retrieve some data from the internet and then to take that data and bundle it up in an Intent and pass it to a new activity(A list display). So in the first activity I just have an EditText and Button. In the event of an OnClick the task should be called and when it is finished the data should be bundled inside an Intent and passed to the next Activity. The problem is when I take the results from onPostExecute and set them to an instance variable of the main activity, that instance variable is still null when the task is complete. Here is the barebones version of the code:
CODE:...........
When I debug the application I see onPostExecute does contain a valid PlacesList full of results, so why is the instance variable places set to null after the task is executed? I am going about "returning data" from an AsyncTask incorrectly?
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Mar 14, 2010
I'm looking into writing simple graphics code in Android and I've noticed some synchronized() blocks. What is the reasoning behind this and how do I know when I should be "synchronizing" my code?
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Sep 1, 2010
What is the class name of media scanner service?
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Oct 2, 2009
if the inner UpdateService class is not static, it cannot start the service. The ActivityManager complains "Unable to start service Intent"...
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Sep 15, 2010
When I create a instance of the SQLiteOpenHelper, I always need a "Context" to be passed as its constructor's argument. To use this "Context", in my service layer class, I extends Activity class, though I do not display this activity on the screen because it is my service layer. I always get NullPointer exception when I open the SQLiteOpenHelper in my service layer class, Is it because my service layer class extends the Activity class but I did not show this activity on mobile screen? (That's there is no intent to my service layer class), if it is so, how to get rid of it if I wanna open a SQLiteOpenHelper in my service layer class which do not need to extends Activity, but need a Context object to pass to SQLiteOpenHelper?
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Jun 18, 2010
In Android, if I want to do some background work, what is the difference between
Creating a Service to do the work, and having the Activity start the Service VS. Creating a standard java class to do the work, and having the Activity create an object of the class and invoke methods, to do the work in separate thread.
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May 8, 2009
I'm posting this to share the lessons I learned while working with IntentService. IntentService has a single constructor that takes a string argument "name". The documentation has no description of what name is used for. In looking at the sources, I found that its only use is in naming the worker thread for the IntentService. This thread is named IntentService [name].
I initially implemented the constructor of the derived class to also take a String argument and passed it along to the derived class. This is wrong. This will cause the startService() call to generated a java.lang.InstantiationException in the application containing the service i.e. you don't get the exception in the application calling startService(). A clue to the actual problem is a little further up in the logs:"newInstance failed: no <init>()"
The derived class must have a Default constructor and that constructor must call super() passing a string for the name component of the worker thread name.
public class MyIntentService extends IntentService {
public MyIntentService() { super("MyIntentService");
} @Override
protected void onHandleIntent(Intent intent) {
// Handle events on worker thread here }
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Jul 2, 2010
I am trying to call my service class's stopService() method from my activity. But I don't know how to access stopservice method from my activity class. I have the below code but its not working. This is HomeScreen class:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
enablecheck = (CheckBox)findViewById(R.id.enablecheck);
enablecheck.setOnCheckedChangeListener(new OnCheckedChangeListener(){
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// TODO Auto-generated method stub
if(enablecheck.isChecked()){
startService(new Intent(HomeScreen.this, AutoService.class));
} else {
stopService(new Intent(HomeScreen.this, AutoService.class));
} } });
}
This is Service Class:
public class AutoService extends Service {
private static final String TAG = "AutoService";
private Timer timer;
private TimerTask task;
@Override
public IBinder onBind(Intent intent) {
return null;
} @Override
public void onCreate() {
Toast.makeText(this, "Auto Service Created", Toast.LENGTH_LONG).show();
Log.d(TAG, "onCreate");
int delay = 5000; // delay for 5 sec.
int period = 5000; // repeat every sec.
timer = new Timer();
timer.scheduleAtFixedRate(task = new TimerTask(){
public void run() {
System.out.println("done");
} }, delay, period);
}
@Override
public boolean stopService(Intent name) {
// TODO Auto-generated method stub
timer.cancel();
task.cancel();
return super.stopService(name);
} }
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Mar 25, 2009
I have created a threaded service the following way. code...
After I close the application the phone works really slow and I guess it is due to thread termination failure.
Does anyone know what is the best way to terminate all threads before terminating the application?
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May 19, 2010
The problem seems to be that the Service class does not inherit the > findViewById() method.
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