jaas.conf

SampleClient {
    com.sun.security.auth.module.Krb5LoginModule required
    debug=true
    useTicketCache=true
    doNotPrompt=true
    renewTGT=true
    ;
};

krb.java

import com.sun.security.auth.callback.TextCallbackHandler;

import javax.security.auth.Subject;
import javax.security.auth.login.LoginContext;
import java.security.AccessController;
import java.security.PrivilegedAction;

/**
 * Created by bill on 3/17/16.
 */
public class krb {
    public static void main(String[] args) throws Exception {
        LoginContext lc = new LoginContext("SampleClient", new TextCallbackHandler());
        lc.login();
        Subject me = lc.getSubject();
        Subject.doAs(me, new PrivilegedAction<Void>() {
            @Override
            public Void run() {
                Subject current = Subject.getSubject(AccessController.getContext());
                String name = current.getPrincipals().iterator().next().getName();
                System.out.println(String.format("Hello, it's me, %s!", name));
                return null;
            }
        });
    }
}

1. compile with javac krb.java
2. kinit as your favorite user
3. run with java -Djava.security.auth.login.config=jaas.conf krb

Sample output:

root@vagrant-ubuntu-trusty-64:~# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: bill/admin@EXAMPLE.COM

Valid starting       Expires              Service principal
03/17/2016 21:18:56  03/18/2016 07:18:56  krbtgt/EXAMPLE.COM@EXAMPLE.COM
    renew until 03/18/2016 21:18:55
root@vagrant-ubuntu-trusty-64:~# kinit bill/admin
Password for bill/admin@EXAMPLE.COM:
root@vagrant-ubuntu-trusty-64:~# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: bill/admin@EXAMPLE.COM

Valid starting       Expires              Service principal
03/17/2016 21:28:42  03/18/2016 07:28:42  krbtgt/EXAMPLE.COM@EXAMPLE.COM
    renew until 03/18/2016 21:28:41
root@vagrant-ubuntu-trusty-64:~# java -Djava.security.auth.login.config=jaas.conf krb
Debug is  true storeKey false useTicketCache true useKeyTab false doNotPrompt true ticketCache is null isInitiator true KeyTab is null refreshKrb5Config is false principal is null tryFirstPass is false useFirstPass is false storePass is false clearPass is false
Acquire TGT from Cache
Principal is bill/admin@EXAMPLE.COM
Commit Succeeded

Hello, it's me, bill/admin@EXAMPLE.COM!