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Difference between Android Service, Thread, IntentService and AsyncTask
Service
- Task with no UI, but shouldn't be too long. Use threads within service for long tasks.
- Triggered from any thread
- Runs on Main Thread
- Limitations:
- May block main thread
Thread
- Long task in general.
- For tasks in parallel use Multiple threads (traditional mechanisms)
- Triggered from any thread
- Runs on its own thread
- Limitations:
- Manual thread management
- Code may become difficult to read
IntentService
- Long task usually with no communication to main thread.
- If communication is required, can use main thread handler or broadcast intents
- When callbacks are needed (Intent triggered tasks).
- Triggered on Main Thread (Intent is received on main thread and then worker thread is spawed)
- Runs on Separate worker thread
- Limitations:
- Cannot run tasks in parallel.
- Multiple intents are queued on the same worker thread.
AsyncTask
- Small task having to communicate with main thread.
- For tasks in parallel use multiple instances OR Executor
- Triggered on Main Thread
- Runs on Worker thread. However, Main thread methods may be invoked in between to publish progress.
- Limitations:
- one instance can only be executed once, thus cannot run in a loop
- Must be created and executed from the Main thread