Error in Creating Custom Business Methods using ADF Business Comp. Tutorial

Question

I've been working with Jdev 10g Preview for a while. Now that we have Jdev 10g, I have to unlearn some of the Preview methods and learn the "real" way of doing things. To that end, I went out to the "Creating Custom Business Methods using ADF Business Components" tutorial. Unfortunately, I've found what I think is a mistake in the example code.
Specifially, ADF treats the default iterator on View Objects differently than previous BC4J versions. In the older versions, the iterator was positioned before the first row when you first executed a query. In that case, the hasNext() method was used to see if you had any rows at all. In ADF, however, the default iterator is positioned at the first row. So, if your query only returns one row, then the hasNext() method returns false!
Here's the code posted in the tutorial:
public Number getDeptSalaryTotal(String dept_id)
// get a department view object
DepartmentsViewImpl dept = getDepartmentsView1();
dept.setWhereClause("DEPARTMENT_ID = " + dept_id);
dept.executeQuery();
dept.first();
EmployeesViewImpl emps = getEmployeesView3();
Number salaryTotal = new Number(0);
while (emps.hasNext() )
Row empsRow = emps.next();
salaryTotal =
salaryTotal.add((Number)(empsRow.getAttribute("Salary")));
return salaryTotal;
As you can see, this is coded using the pre-10g semantics. It checks hasNext() at the top of the while loop. If there is only one Employee in the Department, hasNext() will return false since the emps View Object will already be positioned at the first and only row. There won't be a next row. So, the salaryTotal will be zero instead of the correct value. Alternatively, if there is more than one row, then hasNext() will be true, but the routine will skip the first row and start totalling salaries from the second row on.
The routine should be recoded as follows:
public Number getDeptSalaryTotal(String dept_id)
// get a department view object
DepartmentsViewImpl dept = getDepartmentsView1();
dept.setWhereClause("DEPARTMENT_ID = " + dept_id);
dept.executeQuery();
dept.first();
EmployeesViewImpl emps = getEmployeesView3();
Number salaryTotal = new Number(0);
Row empsRow = emps.first(); // Get the first row
while (empsRow != null ) // while we have a row
salaryTotal =
salaryTotal.add((Number)(empsRow.getAttribute("Salary"))); // add in the salary
empsRow = emps.next(); // get the next row
return salaryTotal;
I haven't actually executed this code, so there may be a typo or two in there. However, the basic idea is sound -- I think!
Please update the tutorial so we don't mislead people right at the start! :-)

Answer 1

Gary:
I have two questions for you:
1) Could you post the preferred code here?
2) Why is it the preferred method? I would think that creating and destroying another object (the temporary iterator) would be a bad thing.