Java Reference
In-Depth Information
}
}
};
Thread thdA = new Thread(r);
thdA.setName("A");
Thread thdB = new Thread(r);
thdB.setName("B");
thdA.start();
thdB.start();
}
}
for100milliseconds.Thissleepresultsineachthreadexecutingmorefrequently,asthe
following partial output reveals:
A: 0
B: 0
A: 1
B: 1
A: 2
B: 2
A: 3
B: 3
A thread will occasionally start another thread to perform a lengthy calculation,
download a large file, or perform some other time-consuming activity. After finishing
itsothertasks,thethreadthatstartedtheworkerthreadisreadytoprocesstheresultsof
the worker thread and waits for the worker thread to finish and die.
Itispossibletowaitfortheworkerthreadtodiebyusingawhileloopthatrepeatedly
calls
Thread
's
isAlive()
methodontheworkerthread's
Thread
objectandsleeps
for a certain length of time when this method returns true. However,
Listing 4-19
demonstrates a less verbose alternative: the
join()
method.
Listing 4-19.
Joining the default main thread with a background thread
class JoinDemo
{
public static void main(String[] args)
