unblocking a read on System.in

As Sendoh suggests, closing a stream will cause any pending reads to return.

Alternatively, you can change the read loops to only invoke read when there are bytes pending to be read, i.e. available returns non-zero.

boolean done = false;
while (!done) {
     if (in.available()) in.read()
     // sleep or wait
}


Then another thread can simply set done = true in order to stop the reading thread.

Just want to point out that there may be a synchronization problem. When 2 threads are working on the same stream object, one read may lock the object and disallow the other to close it.

Neither the "read" nor the "close" methods on a stream are synchronized.