When to use a Service or AsyncTask or Handler?

Question

Can someone tell me the TRUE difference?

Answer 1

Service

A Service is an application component that can perform long-running operations in the background and does not provide a user interface. Another application component can start a service and it will continue to run in the background even if the user switches to another application. Additionally, a component can bind to a service to interact with.

When to use?

Task with no UI, but shouldn’t be too long. Use threads within service for long tasks. Long task in general.

Trigger: Call to method onStartService()

Triggered from: Any Thread

Runs on: Main thread of its hosting process. The service does not create its own thread and does not run in a separate process (unless you specify otherwise)

Limitations / Drawbacks: May block main thread

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AsyncTask

AsyncTask enables the proper and easy use of the UI thread. This class allows performing background operations and publishing results on the UI thread without having to manipulate threads and/or handlers. An asynchronous task is defined by a computation that runs on a background thread and whose result is published on the UI thread.

When to use?

Small task having to communicate with main thread For tasks in parallel use multiple instances OR Executor Disk-bound tasks that might take more than a few milliseconds

Trigger: Call to method execute()

Triggered from: Main Thread

Runs on: Worker thread. However, Main thread methods may be invoked in between to publish progress.

Limitations / Drawbacks:

• One instance can only be executed once (hence cannot run in a loop)
• Must be created and executed from the Main thread

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