Java Reference
In-Depth Information
public double getResult() {
return result;
}
public double calculate() {
// ... calculate a value for "result"
}
}
class ShowJoin {
public static void main(String[] args) {
CalcThread calc = new CalcThread();
calc.start();
doSomethingElse();
try {
calc.join();
System.out.println("result is "
+ calc.getResult());
} catch (InterruptedException e) {
System.out.println("No answer: interrupted");
}
}
// ... definition of doSomethingElse ...
}
First, a new thread type,
CalcThread
, is defined to calculate a result.
We start a
CalcThread
, do something else for a while, and then
join
that thread. When
join
returns,
CalcThread.run
is guaranteed to have
finished, and
result
will be set. If
CalcThread
is already finished when
doSomethingElse
has completed,
join
returns immediately. When a thread
dies, its
Thread
object doesn't go away, so you can still access its state.
You are not required to join a thread before it can terminate.
Two other forms of
join
take time-out values analogous to
wait
. Here
are the three forms of
join
:
