Empty Oracle schemas without deleting the schema and recreating it. http://technology.amis.nl/2004/11/08/sql-script-to-empty-outcleanse-a-user-schema/

empty_oracle_schemas.sql

SELECT 'drop ' ||object_type || ' '|| owner||'.' || object_name || ';'
  FROM dba_objects
    WHERE owner in ('USER1', 'USER2')
      AND object_type not in ( 'PACKAGE BODY', 'INDEX', 'TABLE', 'TRIGGER', 'UNDEFINED')
UNION
SELECT 'drop ' || object_type || ' ' || owner||'.'||object_name || ' cascade constraints;'
  FROM dba_objects
  WHERE owner in ('USER1', 'USER2')
    AND object_type = 'TABLE';