Question

I have 2 questions in terms of android development and threads

1) When do you think I should use threads in android development?

2) If I have the main UI thread waiting on some variable to be set before it displays a toast, then I thought about having a while(true) loop in a sperate thread that keeps checking that variable. Now if the variable is set, how do I call the method on the first thread (The UI thread) that will display a toast

Thank you so much

Answer 1

Using threads directly is not necessary in most cases. The android facilities for threaded programming are great, and easy to use.

You have about three options to call the UI thread from another thread:

• Handler – set an handler on the other thread from the UI thread, and send it a message when need.
• AsyncTask – Perform the main task in background, but modify the UI before, during and after completion.
• PerformOnUiThread – call this method with a runnable to modify the UI on the UI thread.

Good article to read about is Painless Threading.