我应该如何设置我的Android Google Maps应用程序？

Question

I have been working on an Android application that uses Google maps and then runs some lengthy network intensive operations in the background. Currently, I am using a thread to run them on and they take anywhere from 30 seconds to 7 minutes to finish. After watching a few courses on Pluralsight about AsyncTasks and Background services, I now know that threads should ideally not be used for anything taking more than a few seconds. I am now altering my solution to run live with GPS rather than taking several minutes to perform the operations. The goal is to update an array every OnLocationChanged event.

I am having trouble in thinking about how I could alter a global array every OnLocationChanged event while also accessing it from the UI main thread. What is my best option for accomplishing this? Would I be able to use a process or AsynTask to accomplish this or would I need to go client/server route? Where would the OnLocationChanged be called?

Answer 1

First off, onLocationUpdated is called on the UI thread. So you don't have to worry about multithreading there.

Secondly- if you have a variable that needs to be touched by two threads you just use a semaphore and take it before you need to access it on each thread, and release it when done. Make sure to keep that block of code as small and quick as possible. There's more advanced stuff you can do for high performance needs, but that's good enough for 99% of code.

Thirdly- as I mentioned in my comment, your understanding of threading is wrong. The UI thread should not be used for more than is needed. AsyncTasks should not run for more than a few seconds (as there's a single thread they run on by default, so running long would block other requests). But a Thread can run as long as it needs to, and should be used if it needs long term background processing.