Handle Input using StreamGobbler

Question

I have been through the StreamGobbler at the following URL

JavaWorld : Stream Gobbler

I understand the usage and the reason on why it has been implemented.

Answer 1

Ideally, you would employ the StreamGobbler on your error stream (in a separate thread) if you are already expecting something on InputStream, to look into when the process.waitFor() returns a non-zero value to find out the error message. If you are not interested in the InputStream, then you can read the ErrorStream directly in your code, once you are done with giving your inputs to the command.

Process proc = Runtime.getRuntime().exec(cmd)
// Start a stream gobbler to read the error stream.
StreamGobbler errorGobbler = new StreamGobbler(proc.getErrorStream());
errorGobbler.start();

OutputStreamWriter osw = new OutputStreamWriter(proc.getOutputStream())
osw.write(mailBody)
osw.close();

int exitStatus = proc.waitFor();
if (0 != exitStatus) {
    /*
     * If you had not used a StreamGobbler to read the errorStream, you wouldn't have
     * had a chance to know what went wrong with this command execution.
     */
    LOG.warn("Error while sending email: " + errorGobbler.getContent());
}