The Cause of InterruptedException

Question

From J2me doc we know that:

java.lang.InterruptedException Thrown when a thread is waiting, sleeping, or otherwise paused for a long time and another thread interrup

Answer 1

Unfortunately, no, the java.io.* classes do not respond to interruptions when they are blocked in read or write methods. Typically what you have to do is close the stream and then handle the IOException that gets thrown. I have this pattern repeated throughout my code:

try {
    for (;;) {
        try {
            inputStream.read(data);

            thread.join();
        }
        catch (IOException exception) {
            // If interrupted this isn't a real I/O error.
            if (Thread.interrupted()) {
                throw new InterruptedException();
            }
            else {
                throw exception;
            }
        }
    }
}
catch (InterruptedException exception) {
}

Alternatively the newer java.nio.* classes do handle interruptions better and generate InterruptedIOExceptions when they are interrupted. Note that this exception is derived from IOException and not from InterruptedException so you will probably need two catch clauses to handle either type of exception, one for InterruptedException and one for InterruptedIOException. And you'll want any inner IOException catch clause to ignore InterruptedIOExceptions.

Answer 2

The behavior of blocking read in response to thread interrupt is, in fact, undefined. See this long-standing bug for details. The short of it is that sometimes you get EOF, sometimes you get IOException.