Question

I am a research student who just started the android programming for 3 weeks and I am trying to write an App which extracts data from accelerometer from the phone and writing it on my phone. My problem is that I would like to run my App (taking data from accelerometer) all time when the phone is up and running. What I mean is that my App has to run all time when somebody is calling, facebooking and so on. Is that possible? I would like to get some references.

Answer 1

What I mean is that my App has to run all time when somebody is
calling, facebooking and so on. Is that possible?

So for long-tasks you can use AsyncTask or Services. If you want to execute some task and it have to run also when its not connected with any Activity(for example Music player, RSS which still run also after release from memory by memory manager), you should decide to use Services and also you can combine Services with AsyncTask.

Services are strong tool but work with them is not trivial. You are able to execute only one Service in time and only one Service can running, one instance, one copy. This all is not free so you have to be careful because when you implement Service too dirty, it may cause premature exhaustion of battery.
There is more approaches how to start Services but you have to read some tutorial and guides.
I recommend to check this: Services, ServicesDemo – Using Android Services, Android Service Tutorial, Local Service | Android Tutorial for Beginners

Also have look at AsyncTask, Android Threads, Handlers and AsyncTask – Tutorial