Android: AsyncTask vs Service

In some cases it is possible to accomplish the same task with either an AsyncTask or a Service however usually one is better suited to a task than the other.

AsyncTasks are designed for once-off time-consuming tasks that cannot be run of the UI thread. A common example is fetching/processing data when a button is pressed.

Services are designed to be continually running in the background. In the example above of fetching data when a button is pressed, you could start a service, let it fetch the data, and then stop it, but this is inefficient. It is far faster to use an AsyncTask that will run once, return the data, and be done.

If you need to be continually doing something in the background, though, a Service is your best bet. Examples of this include playing music, continually checking for new data, etc.

Also, as Sherif already said, services do not necessarily run off of the UI thread.

For the most part, Services are for when you want to run code even when your application's Activity isn't open. AsyncTasks are designed to make executing code off of the UI thread incredibly simple.

Services are completely different: Services are not threads!

Your Activity binds to a service and the service contains some functions that when called, blocks the calling thread. Your service might be used to change temperature from Celsius to Degrees. Any activity that binds can get this service.

However AsyncTask is a Thread that does some work in the background and at the same time has the ability to report results back to the calling thread.

Just a thought: A service may have a AsyncTask object!

Service is one of the components of the Android framework, which does not require UI to execute, which mean even when the app is not actively used by the user, you can perform some operation with service. That doesn't mean service will run in a separate thread, but it runs in main thread and operation can be performed in a separate thread when needed. Examples usages are playing music in background, syncing data with server in backgroud without user interaction etc

AsyncTask on other hand is used for UI blocking tasks to be performed on a separate thread. It is same like creating a new thread and doing the task when all the tasks of creating and maintaining the threads and send back result to main thread are taken care by the AsyncTask Example usage are fetching data from server, CRUD operations on content resolver etc

Service and asynctasks are almost doing the same thing,almost.using service or a asynctask depends on what is your requirement is.

as a example if you want to load data to a listview from a server after hitting some button or changing screen you better go with a asynctask.it runs parallel with main ui thread (runs in background).for run asynctack activity or your app should on main UI thread.after exit from the app there is no asynctask.

But services are not like that, once you start a service it can run after you exit from the app, unless you are stop the service.like i said it depends on your requirement.if you want to keep checking data receiving or check network state continuously you better go with service.

happy coding.

In few cases, you can achieve same functionality using both. Unlike Async Task, service has it's own life cycle and inherits Context (Service is more robust than an Async Task). Service can run even if you have exited the app. If you want to do something even after app closing and also need the context variable, you will go for Service.

Example: If you want to play a music and you don't want to pause if user leaves the app, you will definitely go for Service.