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.