If i assign an id to an object with a generator id class of type "sequence", will hibernate use the id I assigned or will it still generate a new id when I insert into the DB?

Hibernate will assign one and ignore the one u assigned. (But I am wondering, instead of asking the question, why would u not write sample codes and experiment with it yourself?)

U might want to consider "sequence-identity", which is "a specialized sequence generation strategy that utilizes a database sequence for the actual value generation, but combines this with JDBC3 getGeneratedKeys to return the generated identifier value as part of the insert statement execution. This strategy is only supported on Oracle 10g drivers targeted for JDK 1.4. Comments on these insert statements are disabled due to a bug in the Oracle drivers."

Also note the "unsaved-value" property (which could be : null|any|none|undefined|id_value) of the <id> tag. It *used to be* important for versions of Hibernate earlier than 3.