Varray of Objects: Initializing, Instantiation, Constructors, ORA-06531

Question

     This is supposed to fill a varray with ten objects, calling methods in those objects and populating the objects from queries, then display fields from the objects via methods.  Error message is in comment at bottom.  Any ideas?
-- Enable screen I/O
SET SERVEROUTPUT ON SIZE 1000000
SET VERIFY OFF
-- object spec
  CREATE OR REPLACE TYPE employee4 AS OBJECT
  o_ename CHAR (20 char),
  o_empno NUMBER (4),
  o_sal NUMBER (10),
  o_thisno NUMBER (4),
  MEMBER FUNCTION get_o_ename RETURN CHAR, MEMBER PROCEDURE set_o_ename (o_thisno IN number),
  MEMBER FUNCTION get_o_empno RETURN NUMBER, MEMBER PROCEDURE set_o_empno (o_thisno IN number),
  MEMBER FUNCTION get_o_sal RETURN NUMBER, MEMBER PROCEDURE set_o_sal (o_thisno IN number),
  CONSTRUCTOR FUNCTION employee4 (o_ename CHAR,o_empno NUMBER,o_sal NUMBER,o_thisno NUMBER) RETURN SELF AS RESULT
-- object body
  CREATE OR REPLACE TYPE BODY employee4 AS
  CONSTRUCTOR FUNCTION employee4 (o_ename IN CHAR,
  o_empno IN NUMBER,
  o_sal IN NUMBER,
  o_thisno IN NUMBER)
  RETURN SELF AS RESULT IS
  BEGIN
  SELF.o_ename := o_ename;
  SELF.o_empno := o_empno;
  SELF.o_sal := o_sal;
  SELF.o_thisno := o_thisno;
  RETURN;
  END;
  -- gets
  MEMBER FUNCTION get_o_ename RETURN CHAR IS
  BEGIN
  RETURN self.o_ename;
  END;
  MEMBER FUNCTION get_o_empno RETURN NUMBER IS
  BEGIN
  RETURN self.o_empno;
  END;
  MEMBER FUNCTION get_o_sal RETURN NUMBER IS
  BEGIN
  RETURN self.o_ename;
  END;
  -- sets
  MEMBER PROCEDURE set_o_ename(o_thisno IN number) IS
  BEGIN
  SELECT ename INTO SELF.o_ename FROM emp WHERE empno = SELF.o_thisno;
  END;
  MEMBER PROCEDURE set_o_empno(o_thisno IN number) IS
  BEGIN
  SELECT empno INTO SELF.o_empno FROM emp WHERE empno = SELF.o_thisno;
  END;
  MEMBER PROCEDURE set_o_sal(o_thisno IN number) IS
  BEGIN
  SELECT sal INTO SELF.o_sal FROM emp WHERE empno = SELF.o_thisno;
  END;
  END;
DECLARE
  -- a varray of employees
  TYPE emp_varray1 IS VARRAY(10) OF employee4;
  varray_of_emps  EMP_VARRAY1;
  -- List of EMPNO's in order of appearance in EMP table (for cross-referencing, single-line retrieval)
  TYPE MYCREF_VARRAY IS VARRAY(10) OF NUMBER(4);
  varray_mycref MYCREF_VARRAY := MYCREF_VARRAY(NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);
  -- make a variable to store one empno
  thisno NUMBER(4);
  -- make a counter
  counter INT;
  -- query variables for the set calls
  q_ename CHAR(20 CHAR);
  q_empno NUMBER(4);
  q_sal NUMBER(10);
BEGIN
  -- Put the first 10 EMPNO's in my cref array
  SELECT empno BULK COLLECT INTO varray_mycref FROM emp WHERE ROWNUM < 11;
  -- Use a loop to retrieve the first 10 objects in the "emp" table and put them in the varray of objects
  FOR counter IN 1..10 LOOP
  thisno := varray_mycref(counter);
  varray_of_emps(counter).set_o_ename(thisno);
  varray_of_emps(counter).set_o_empno(thisno);
  varray_of_emps(counter).set_o_sal(thisno);
  END LOOP;
  -- Use another loop to display the information in the reverse order.
  FOR counter in REVERSE 1..10 LOOP
  dbms_output.put_line((varray_of_emps(counter).get_o_ename()) || CHR(9) || (varray_of_emps(counter).get_o_empno()) || CHR(9) || (varray_of_emps(counter).get_o_sal()));
  END LOOP;
END;
  This results in the following response in SQL*PLUS:
Type created.
Type body created.
DECLARE
ERROR at line 1:
ORA-06531: Reference to uninitialized collection
ORA-06512: at line 33

Answer 1

Hi,
From metalink:
Cause: An element or member function of a nested table or varray was
referenced (where an initialized collection is needed) without the
collection having been initialized.
Action: Initialize the collection with an appropriate constructor or
whole-object assignment.
ORA 6531 Reference to uninitialized collection (Doc ID 48912.1)