Getting machine's hostname

Hostname.java

public class SystemUtils {

    private static final Logger LOGGER = LoggerFactory.getLogger(SystemUtils.class);

    private static final String HOSTNAME_VARIABLE = "HOSTNAME";

    private static final String HOSTNAME_COMMAND = "hostname";

    private SystemUtils() {}

    public static String getHostname() throws IOException {
        final String hostname = System.getenv(HOSTNAME_VARIABLE);

        if (hostname == null) {
            final Process p = Runtime.getRuntime().exec(HOSTNAME_COMMAND);
            final BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
            final StringBuilder outputBuilder = new StringBuilder();

            String line;
            while ((line = in.readLine()) != null) {
                outputBuilder.append(line);
            }

            LOGGER.debug("Returning output from executing \'hostname\' command");

            return outputBuilder.toString();
        }

        LOGGER.debug("Returning hostname from the HOSTNAME environment variable");

        return hostname;
    }
}