AndroidService

Thread

1) Service is run on MAIN thread so if we want to execute heavy task we need to create a worker thread for execute it to prevent Android Not Responding.
2) The onHandleIntent inside Intent Service run on worker thread

Type of Service

Unbound Service	Bound Service	Intent Service
Use to make a task for long time and repeat.	Like client(`eg: a screen`)-server (`Service`) model, client bind to server, server execute task and notify data to client.	Use to execute task in worker thread (inside onHandleIntent method). It quite same `AsyncTask` my answer here
start by `startService()`.	start by `bindService()`.	start by `startService()`. When start service, we will also send the intent (with data) to service. Then service will receive data and execute corresponding task. If we send multiple task durring service running, service will execute it sequentially synchronize (thread safe)
stop by `stopService()`.	stop when no client by to this Service . Client unbind service by `unbindService()`.	Auto stop when the task inside `onHandleIntent` execute finished, or we can use `stopself()`
INDEPENDENT with the component started it.	DEPENDENT with the component started it.	INDEPENDENT with the component started it.

Use Unbound Service or Intent Service

Look like Unbound Service and Intent Service have many thing similar however it have some different like

Unbound Service don’t auto stop, Intent Service have
Intent Service have a available method run on worker thread (onHandleIntent), Unbound Service don’t have

=> Unbound Service is suitable for running some long and repeat task . Intent Service is suitable for run some less longer and less repeat task.

Strangely

If we want service keep running after application is destroyed, we need to use flag START_STICKY. Then when application is destroyed, service will destroyed too, then it will recreated. However, for some specific device, Service will not restart (because the manufacture want to save the device battery) (more details)(https://stackoverflow.com/questions/41627537/)service-not-start-again-after-kill-app-even-use-start-sticky-in-some-device
When bind service, if use use flag 0 instead of BIND_AUTO_CREATE, service will not created. After that, when we start service programmatically by call startService, all the client that bind to service before will auto bind to service

Note