InetAddress.getLocalHost() throws UnknownHostException

jhwist picture jhwist · Dec 10, 2009 · Viewed 97.6k times · Source

I am testing our server-application (written Java) on different operating systems and thought that OpenSolaris (2008.11) would be the least troublesome due to the nice Java integration. Turns out I was wrong, as I end up with a UnknownHostException

try {
  computerName = InetAddress.getLocalHost().getHostName();
  if (computerName.indexOf(".") > -1)
    computerName = computerName.substring(0,
        computerName.indexOf(".")).toUpperCase();
} catch (UnknownHostException e) {
  e.printStackTrace();
}

The output is:

java.net.UnknownHostException: desvearth01: desvearth01
    at java.net.InetAddress.getLocalHost(InetAddress.java:1353)

However, nslookup desvearth01 returns the correct IP address, and nslookup localhost returns 127.0.0.1 as expected. Also, the same code works perfectly on FreeBSD. Is there anything special to OpenSolaris that I am not aware of?

Any hints appreciated, thanks.

Answer

jhwist picture jhwist · Dec 10, 2009

In good tradition, I can answer my own question once again:

It seems that InetAddress.getLocalHost() ignores the /etc/resolv.conf, but only looks at the /etc/hosts file (where I hadn't specified anything besides localhost). Adding the IP and hostname to this file solves the problem and the exception is gone.


Another answer is almost correct and I got hint from above and my problem get resolved...Thanks.

But to improve this, I am adding steps-by-steps changes, so that it will be helpful for even naive users.

Steps:

  • Open /etc/hosts, the entries might look like below.

     127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4  
     ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
    
  • You need to add one more line above of this by any editor like vi or gedit (e.g. <your-machine-ip> <your-machine-name> localhost).

     192.168.1.73 my_foo localhost
    

Now, overall file may look like this:

192.168.1.73 my_foo localhost
127.0.0.1    localhost localhost.localdomain localhost4 localhost4.localdomain4
::1          localhost localhost.localdomain localhost6 localhost6.localdomain6
  • Just save it and run again your Java code... your work is done.