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My application does a sync process every 30 seconds.

What I do is, send some data, and accordingly get a set of data, and update/insert into my local sqlite DB. Sometimes, I updated my GUI as a result of these operations.

I read in several posts that an asynctask can do this task perfectly, and in some other posts many people discouraged the use of asynctask, and told me to implement the intentService/broadcast receiver approach.

Which one is better? and when ?

tony9099
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2 Answers2

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There are multiple considerations that you must weigh in order to best decide how to approach your situation. Acording to the doc:

...an activity that initiates a long-running operation might do well to start a service for that operation, rather than simply spawn a thread — particularly if the operation will likely outlast the activity. Examples of this are playing music in the background and uploading a picture taken by the camera to a web site. Using a service guarantees that the operation will have at least "service process" priority, regardless of what happens to the activity.

A Service is a part of your Application that has no UI. It may be called by a UI(Activity) to be started, or may be started by any other component of your Application. When developing, you have the freedom to place it on a different thread, or even run it in a different Task or Process. This allows you to ultimately separate it from your UI. Additionally, you may start the Service to run independently (startService) or bind your activity to it (bindService) depending upon your needs. By using custom Handlers, you can set callbacks to update the UI with your progress. A Service does not necessarily end if a User changes Activities, but may be ended at ANY time by the OS.

A AsyncTask is always instantiated from the UI thread. It only allows specific callbacks, but simplifies the process of multi-threading for the purposes of relatively short transactions (as compared to dedicated separate threaded services) that are inherently tied to actions performed by an Activity. Whenever a User changes Activities, the AsyncTask is put on "pause" and may even die because there is no UI thread for your Activity any longer.

The problem with the AsyncTask is if the user goes to another Activity you can't transfer that object to the other Activity so it dies. There are tricks you can play when say the user rotates the screen or something like that, but that doesn't extend to general purpose destruction. AsyncTask can randomly die. On the other hand you can definitely communicate between Service and Activity, but it's tricky to do it right.

So, depending on your scenario, you have to take a design decision.

Diego Palomar
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  • when does an asynctasked paused ? after onDestroy() is called or after onPause()/onStop(). – tony9099 Oct 31 '13 at 20:29
  • http://stackoverflow.com/questions/3817272/android-design-considerations-asynctask-vs-service-intentservice?rq=1 – nobalG Sep 01 '14 at 09:43
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If you need to update the UI then AsyncTask will be a better fit, however if you need it to update in the background when the app is not running then IntentService would be better and you will need to come up with a way to update the UI from your IntentService

This is more of an opinion based question so I would not expect one definite answer. Its a per-app basis question

tyczj
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