Java

import java.io.*;
public class Test{
public static void main(String args[]) throws IOException{
//JDK1.5
System.out.println(System.getenv("USERDOMAIN"));

//Pre-JDK1.5
Process p = Runtime.getRuntime().exec("cmd.exe /c echo %USERDOMAIN%");
BufferedReader br = new BufferedReader
( new InputStreamReader( p.getInputStream() ) );
String myvar = br.readLine();
System.out.println(myvar);

}
}