Java Iterator backed by a ResultSet

Question

I\'ve got a class that implements Iterator with a ResultSet as a data member. Essentially the class looks like this:

public class A implements Iterator{
            


        

Answer 1

I think there's enough decry over why it's a really bad idea to use ResultSet in an Iterator (in short, ResultSet maintains an active connection to DB and not closing it ASAP can lead to problems).

But in a different situation, if you're getting ResultSet (rs) and are going to iterate over the elements, but you also wanted to do something before the iteration like this:

if (rs.hasNext()) { //This method doesn't exist
    //do something ONCE, *IF* there are elements in the RS
}
while (rs.next()) {
    //do something repeatedly for each element
}

You can achieve the same effect by writing it like this instead:

if (rs.next()) {
    //do something ONCE, *IF* there are elements in the RS
    do {
        //do something repeatedly for each element
    } while (rs.next());
}