Threads - The Java Programming Language - page 543

Interrupting a thread will normally not affect what it is doing, but a
few methods, such as sleep and wait , throw InterruptedException . If your
thread is executing one of these methods when it is interrupted, the
method will throw the InterruptedException . Such a thrown interruption
clears the interrupted state of the thread, so handling code for Interrup-
tedException commonly looks like this:
void tick(int count, long pauseTime) {
try {
for (int i = 0; i < count; i++) {
System.out.println('.');
System.out.flush();
Thread.sleep(pauseTime);
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
The tick method prints a dot every pauseTime milliseconds up to a max-
imum of count timessee " Timer and TimerTask " on page 653 for a better
way to do this. If something interrupts the thread in which tick is run-
ning, sleep will throw InterruptedException . The ticking will then cease,
and the catch clause will reinterrupt the thread. You could instead de-
clare that tick itself throws InterruptedException and simply let the ex-
ception percolate upward, but then every invoker of tick would have
to handle the same possibility. Reinterrupting the thread allows tick to
clean up its own behavior and then let other code handle the interrupt
as it normally would.
In general any method that performs a blocking operation (either dir-
ectly or indirectly) should allow that blocking operation to be cancelled
with interrupt and should throw an appropriate exception if that occurs.
This is what sleep and wait do. In some systems, blocking I/O operations
will respond to interruption by throwing InterruptedIOException (which
is a subclass of the general IOException that most I/O methods can