---> J2EE is open development cost is cheap.Also Databases like Mysql, PostgreSQL which are commonly used in J2ee are free too and it is very useful for developing Enterprise application
J2EE is Platform Independent: Due to Platform Independent nature It can work in any os like windows, linux, mac and so on.

--->Integration with existing information systems (i.e,) integration APIs for: DBs, mail, CORBA, messaging, directories

--->Interoperatability and vendor neutrality.Running j2ee applications is simple.It just need a server which support j2ee standard jsp,servlets,taglibs,etc like tomcat, jboss, websphere