Java Reference
In-Depth Information
Listing 7.9. Interrupting a Task in a Dedicated Thread.
ExecutorService.submit
returns a
Future
describing the task.
Future
has a
cancel
method that takes a boolean argument,
mayInterruptIfRunning
, and returns
a value indicating whether the cancellation attempt was successful. (This tells you only
whether it was able to deliver the interruption, not whether the task detected and acted on
it.) When
mayInterruptIfRunning
is
true
and the task is currently running in some
thread, then that thread is interrupted. Setting this argument to
false
means “don't run this
task if it hasn't started yet”, and should be used for tasks that are not designed to handle in-
terruption.
Since you shouldn't interrupt a thread unless you know its interruption policy, when is it OK
to call
cancel
with an argument of
true
? The task execution threads created by the stand-
ard
Executor
implementations implement an interruption policy that lets tasks be cancelled
