Getting the computer name in Java

Question

I was wondering if there is a way to get the computer name in Java  I have seen several answers that feature java net InetAddress  However I was wondering if there is a way that does not use the network    As a side question  is the computer name only a network thing anyway  so therefore has to be done this way

User · Answer

I agree with peterh s answer  so for those of you who like to copy and paste instead of 60 more seconds of Googling   private String getComputerName         Map lt String  String gt  env   System getenv        if  env containsKey  COMPUTERNAME            return env get  COMPUTERNAME        else if  env containsKey  HOSTNAME            return env get  HOSTNAME        else         return  Unknown Computer       I have tested this in Windows 7 and it works  If peterh was right the else if should take care of Mac and Linux  Maybe someone can test this  You could also implement Brian Roach s answer inside the else if you wanted extra robustness

User · Answer

The computer  name  is resolved from the IP address by the underlying DNS  Domain Name System  library of the OS  There s no universal concept of a computer name across OSes  but DNS is generally available  If the computer name hasn t been configured so DNS can resolve it  it isn t available   import java net InetAddress  import java net UnknownHostException   String hostname    Unknown    try       InetAddress addr      addr   InetAddress getLocalHost        hostname   addr getHostName      catch  UnknownHostException ex        System out println  Hostname can not be resolved

User · Answer

I m not so thrilled about the InetAddress getLocalHost   getHostName   solution that you can find so many places on the Internet and indeed also here  That method will get you the hostname as seen from a network perspective  I can see two problems with this    What if the host has multiple network interfaces   The host may be known on the network by multiple names  The one returned by said method is indeterminate afaik  What if the host is not connected to any network and has no network interfaces     All OS es that I know of have the concept of naming a node host irrespective of network  Sad that Java cannot return this in an easy way  This would be the environment variable COMPUTERNAME on all versions of Windows and the environment variable HOSTNAME on Unix Linux MacOS  or alternatively the output from host command hostname if the HOSTNAME environment variable is not available as is the case in old shells like Bourne and Korn    I would write a method that would retrieve  depending on OS  those OS vars and only as a last resort use the InetAddress getLocalHost   getHostName   method  But that s just me   UPDATE  Unices   As others have pointed out the HOSTNAME environment variable is typically not available to a Java application on Unix Linux as it is not exported by default  Hence not a reliable method unless you are in control of the clients  This really sucks  Why isn t there a standard property with this information   Alas  as far as I can see the only reliable way on Unix Linux would be to make a JNI call to gethostname   or to use Runtime exec   to capture the output from the hostname command  I don t particularly like any of these ideas but if anyone has a better idea I m all ears   update  I recently came across gethostname4j which seems to be the answer to my prayers    Long read  I ve created a long explanation in another answer on another post  In particular you may want to read it because it attempts to establish some terminology  gives concrete examples of when the InetAddress getLocalHost   getHostName   solution will fail  and points to the only safe solution that I know of currently  namely gethostname4j   It s sad that Java doesn t provide a method for obtaining the computername  Vote for JDK-8169296 if you are able to

[java] Getting the computer name in Java

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