how do i interrupt a running thread

[Lion Z. Li]

Hi,
How do i stop a thread instead of waiting for it reach the end of run() method. Here are some cases:
A) A thread is waiting on some object by calling someobject.wait();
B) A thread is being Blocked on IO routin, say network stream read and write.
C) A thread is busy within a while(true){} loop doing its fine works.
D) ... and some other situations i still dont know.
Would you please help me with these problems?

[Christian Wolf]

Hello.
C) A thread is busy within a while(true){} loop doing its fine works.
Check a parameter in the while condition instead of true that you can set from the outside. while(a==0) {} with "a" being a public variable in your thread class. Setting "a" to 1 will terminate your thread after the current loop finished.
A) A thread is waiting on some object by calling someobject.wait();
Wrap the wait() inside a loop as described in C, and specify a timeout for wait, e.g. someobject.wait(5000); to wait 5 seconds. Then you can test an abort condition in the while() and you can even set a timeout inside your thread class when the loop has run a certain number of times without the wait() being interrupted by notify(). You have to catch InterruptedException that tells you whether wait() got a timeout (5000 ms) or an interruption.
B) A thread is being Blocked on IO routin, say network stream read and write.
I do not know. I think, blocked means blocked. You cannot do much besides waiting outside the thread for the execution of the IO request and proceed if a timeout occurs. Maybe the thread gets deleted when the reference is deleted but I don't think so.
Christian Wolf
[edit 2]
[ January 19, 2004: Message edited by: Christian Wolf ]

[Michael Yuan]

I agree with Christian. You need to use some condition inside the run() method to determine when to abort. Java used to have a "Thread.stop()" method but it is not safe and not supported in J2ME.

[serge masse]

B) A thread is being Blocked on IO routin, say network stream read and write.

For this situation, I recommend that in a second thread you close the IO stream that the blocked thread is using, for example: stream.close(). You should also catch in the IO thread the IOException that will be thrown when the close() gets done in the second thread. It is also good practice to catch any IOException that can be thrown in the second thread, the one calling the stream.close() method, in case it is thrown for some reason ... which often occur with IO.

[Christian Wolf]

For this situation, I recommend that in a second thread you close the IO stream that the blocked thread is using, for example: stream.close(). You should also catch in the IO thread the IOException that will be thrown when the close() gets done in the second thread.
Interesting idea. But if the IO is hanging at HttpConnection.getResponseCode() and the remote server is not reachable, then I cannot close any stream as the outputstream for sending data has already been closed before and the input stream is opened after getting the responsecode only. The HttpConnection itself times out after ~20 seconds (on my emulator) and throws an IOException (Network read error).
It is also good practice to catch any IOException that can be thrown in the second thread, the one calling the stream.close() method, in case it is thrown for some reason ... which often occur with IO.
I am also not quite sure how it works that I open the connection in one thread and catch thrown exceptions in another one. Can you please describe this a bit more?
Christian Wolf

[Christian Wolf]

For this situation, I recommend that in a second thread you close the IO stream that the blocked thread is using

Boah, that was easy. Inside my Http thread class that opens the HttpConnection, I specified a private sub thread (TimeOutThread) that I start before I open the HttpConnection. The first action of TimeOutThread is sleep(10000). After these 10 seconds, I check for a variable that is changed after responseCode() returns. So I know whether HttpConnection still tries to connect to the remote server. If this is the case, I just call HttpConnection.close(). In my main thread, I get an IO exception ("user abort") and the thread finishes. Great! Thanks.
Before I made this, I had a timeout specified in the UI thread. Very stupid, of course.
What is a reasonable setting for the timeout? 10 seconds? 15 seconds? My application will run on a 3G network.
Christian Wolf