Re: Threads and UI in Android
On 04/04/2011 01:51, markspace wrote:
On 4/3/2011 3:16 PM, Lawrence D'Oliveiro wrote:
In message<8vs005F5tmU1@mid.individual.net>, Dirk Bruere at NeoPax wrote:
It would seem the answer is in here somewhere
http://developer.android.com/resources/articles/painless-threading.html
Seems like AsyncTask is the way to go: it automatically divides up
execution
between a background thread and the UI thread, and takes care of all the
synchronization between the two for you.
How much more painless can you get? :)
Given that the OP want's to "constantly [check] for messages" I think
the way he's doing it now is fine. runOnUiThread() does the
synchronization that he needs, and it seems cleaner than trying to wrap
his deamon in an AsyncTask object and constantly call publishProgress()
whenever he gets a packet.
Modern threading is getting sophisticated, and one sophisticated thing
to do is to limit the number of threads so as to not overwhelm the OS.
Limited thread pools are used for this purpose. I don't know how
AsynchTask is implemented, but if it uses a thread pool, you could
easily starve your own app of threads for AsynchTask by permanently
capturing too many AsynchTask threads, which is what the OP's task would
do.
"Long running" tasks relative to the UI response time go in AsynchTask.
"Really long running" tasks, or permanent tasks like the OP's little
network daemon, go in their own private thread. Seems safest that way.
Currently I have this:
public class BlinkDataThread extends Thread
{
int length = Constants.PACKET_LENGTH;
byte[] receiveBuffer = new byte[length];
DatagramSocket socket;
DatagramPacket packet;
public void run()
{
try
{
DatagramSocket ds = new DatagramSocket(Constants.LOCAL_PORT);
DatagramPacket incoming = new DatagramPacket(receiveBuffer,
receiveBuffer.length);
incoming.setLength(length);
String packetStr=new String(receiveBuffer, "UTF-8");
while(true) //Run this as an endless loop
{
ds.setReceiveBufferSize(receiveBuffer.length);
ds.receive(incoming);
packetStr = new String(receiveBuffer, 0,
incoming.getLength(), "UTF-8");
if (packetStr != null) BlinkAPI.updateIncomingData(packetStr);
}
} catch (IOException e1) {}
}
}
Where linkAPI.updateIncomingData(packetStr); is the offending bit since
it triggers updates on the UI thread.
That would be where I use runOnUiThread()?
--
Dirk
http://www.neopax.com/technomage/ - My new book - Magick and Technology