kerberos kinit implementations, support a "-r" option which allows users to 
obtain a renewable ticket. 

      /usr/bin/kinit [-ARvV] [-p | -P] [-f | -F] [-a] [-c cache_name] 
           [-C] [-E] [-k [-t keytab_file]] [-l lifetime] 
           [-r renewable_life] [-s start_time] [-n] [-S service_name] 
           [-X attribute[=value]] [-T armor_ccache] [principal] 
 
But Java's kinit implementation does not allow for a renewable options 
 
 C:\Program Files\Java\jdk1.7.0_55\bin>kinit.exe -help 
 Usage: kinit [-A] [-f] [-p] [-c cachename] [[-k [-t keytab_file_name]] 
 [principal] [password] 
        available options to Kerberos 5 ticket request: 
             -A   do not include addresses 
             -f   forwardable 
             -p   proxiable 
             -c   cache name (i.e., FILE:\d:\myProfiles\mykrb5cache) 
             -k   use keytab 
             -t   keytab file name 
             principal   the principal name (i.e., qweadf@ATHENA.MIT.EDU qweadf) 
            password   the principal's Kerberos password 
 
 C:\Program Files\Java\jdk1.7.0_55\bin> 
 
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/kinit.html   

Also,Can we add an extra function along with "renewable" that allows users to 
set the expiry time please? That is the "-l" option, which can be used to set 
the lifetime of the kerberos ticket. Here is the extract from the krb5 spec: 

-l lifetime 
(Time duration string.) Requests a ticket with the lifetime "lifetime". 
For example, kinit -l 5:30 or kinit -l 5h30m 
If the -l option is not specified, the default ticket lifetime (configured by each site) is used. 
Specifying a ticket lifetime longer than the maximum ticket lifetime 
(configured by each site) will not override the configured maximum ticket lifetime. 

Also, I noticed that Java Kinit doesn't honour the krb5.conf setting 
"ticket_lifetime" or "renew_lifetime". Not sure if it's something you want to 
support in Java, thought I would mention this as well.