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Daemon Thread

shri mon
Ranch Hand

Joined: Jan 11, 2005
Posts: 63
Should we know about daemon threads for the scjp1.4?
The kb book does not deal with that.
Can anyone who has taken the exam explain?

Thanks in advance..
Ren� Star

Joined: Feb 24, 2005
Posts: 13
Basically this is all there is to know about daemon threads:

1. You can have two types of threads inside a Java program, user threads and daemon threads.
2. A Java program terminates when all USER threads have died, regardless of the existence of any living daemon threads.
3. You can change the status of a thread by using the setDaemon method as long as the thread has not been started. If you try to change a started thread, you'll get an IllegalThreadStateException.

Relevant methods:
final void setDaemon(boolean flag)
If flag is true, the thread will become a daemon thread. Otherwise the thread becomes a user thread. (BTW, threads are created as user threads initially)

final boolean isDaemon()
Returns true if the thread is a daemon thread; false if it is a user thread.

Hope this helps.
shri mon
Ranch Hand

Joined: Jan 11, 2005
Posts: 63
Thanks a lot.
I agree. Here's the link:
subject: Daemon Thread
It's not a secret anymore!