Documentation for this section has not yet been entered.
Checks whether this connection has gone down. Network connections may get closed during some time of inactivity for several reasons. The next time a read is attempted on such a connection it will throw an IOException. This method tries to alleviate this inconvenience by trying to find out if a connection is still usable. Implementations may do that by attempting a read with a very small timeout. Thus this method may block for a small amount of time before returning a result. It is therefore an expensive operation.