How to refresh materialized view in oracle

Run this script to refresh data in materialized view:

BEGIN
DBMS_SNAPSHOT.REFRESH('Name here');
END;

try this:

DBMS_SNAPSHOT.REFRESH( 'v_materialized_foo_tbl','f'); 

first parameter is name of mat_view and second defines type of refresh. f denotes fast refresh. but keep this thing in mind it will override any any other refresh timing options.