Is it possible to read from a InputStream with a timeout?

Question

Specifically, the problem is to write a method like this:

int maybeRead(InputStream in, long timeout)

where the return value is the same as in.read() if data is available within 'timeout' milliseconds, and -2 otherwise. Before the method returns, any spawned threads must exit.

To avoid arguments, the subject here java.io.InputStream, as documented by Sun (any Java version). Please note this is not as simple as it looks. Below are some facts which are supported directly by Sun's documentation.

1. The in.read() method may be non-interruptible.
2. Wrapping the InputStream in a Reader or InterruptibleChannel doesn't help, because all those classes can do is call methods of the InputStream. If it were possible to use those classes, it would be possible to write a solution that just executes the same logic directly on the InputStream.
3. It is always acceptable for in.available() to return 0.
4. The in.close() method may block or do nothing.
5. There is no general way to kill another thread.

Answer 1

I would question the problem statement rather than just accept it blindly. You only need timeouts from the console or over the network. If the latter you have Socket.setSoTimeout() and HttpURLConnection.setReadTimeout() which both do exactly what is required, as long as you set them up correctly when you construct/acquire them. Leaving it to an arbitrary point later in the application when all you have is the InputStream is poor design leading to a very awkward implementation.