Of course, u can use java.util.GregorianCalendar class to do things with the Time and Date stuff...
Java does have java.lang.Runtime class to deal with the low level commands as well... But there is a limitation on how low Java can dig into the system...
Co-author of SCMAD Exam Guide, Author of JMADPlus
SCJP1.2, CCNA, SCWCD1.4, SCBCD1.3, SCMAD1.0, SCJA1.0, SCJP6.0