Sree, If you haven't already done so, please refer to the section entitled ResultSet Limitations in Oracle's JDBC User's Guide and Reference. Not all queries can produce updatable "ResultSet"s. As stated in the Oracle documentation, the Oracle JDBC driver will silently convert updatabale "ResultSet"s to read-only "ResultSet"s for such queries.
In your case, it looks like "select * from EMP" cannot produce an updatable "ResultSet".
By the way, the Oracle documentation also states that there may be problems in using "select *", and recommends using explicit column lists instead.
Perhaps you shoud [re?] read the Oracle documentation?