alexk-il wrote:
> Hi,
>
> I'm really enjoying Mark's "Beginning Android" - everything is clear
> and straight to the point.
>
> I wonder why in the Threading example the "isRunning" flag wasn't
> declared "volatile". The flag is used to stop a thread from another
> thread.
>
> In case you have the book (or even wrote it :) ) - it's on page 143.
> In case you don't, the simplified version of the code goes like this:
>
> public class fooBar extends Activity{
> ...
> public void onStart() {
> super.onStart();
>
> // why not volatile?
> boolean isRunning=false;
>
> Thread BG=new Thread(new Runnable() {
> public void run() {
> try {
> while(isRunning){
> // Do something
> }
> }
> catch (Throwable t) {
> // Do something
> }
> });
>
> isRunning=true;
> background.start();
> }
>
> public void onStop() {
> super.onStop();
> isRunning=false;
> }
> }
>
> I know, the code works on android, so what am I mising here?
Hmmmmm...
Usually, I use AtomicBoolean rather than volatile, but I apparently used
neither here. On the whole, booleans are as thread-safe as a datatype
gets, since we're only talking about a bit. That being said, I am being
a bit sloppy there, and should improve matters.
Thanks for pointing it out!
BTW, you're welcome to use the [cw-android] Google Group for questions
on _Beginning Android_:
http://groups.google.com/group/cw-android
--
Mark Murphy (a Commons Guy)
http://commonsware.com | http://twitter.com/commonsguy
Android Training in US: 8-12 February 2010: http://bignerdranch.com
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