Re: Opinion poll: for loop vs while loop with Iterators.

From:

"Daniel Dyer" <"You don't need it">

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 21 Dec 2006 20:57:18 -0000

Message-ID:

<op.tkxghstb8kxvgr@jack.local>

On Thu, 21 Dec 2006 20:40:45 -0000, Daniel Pitts =

<googlegroupie@coloraura.com> wrote:

Java 1.5 finaly gave us an elegant for each construct, but for-each
lacks the ability to manipulate the underlying Iterable structure.

Generally, the way to do this is (in pseudo-code:)

Obtain the iterator.
L: Check if it has a next element
get the next element
process the element.
repeat from L

This can be coded in Java a few ways.
// For method:
for (Iterator<E> iterator = iterable.iterator(); iterator.hasNext();=

)

{
   E e = iterator.next();
   if (shouldRemove(e)) {
      iterator.remove(e);
   }
}

// vs
// While method:
Iterator<E> iterator = iterable.iterator();
while (iterator.hasNext()) {
   E e = iterator.next();
   if (shouldRemove(e)) {
      iterator.remove(e);
   }
}

Both approaches have their pros and cons, but I'm interested to see
what people think.

I'll post my opinion later.

The for loop is one line shorter but I've always preferred the while =

loop. It justs seems more natural and more readable to me. When I was =
at =

school, programming in BASIC and Pascal with less flexible for loops, fo=
r =

loops were for a fixed number of iterations known at the start, and whil=
e =

loops for an indeterminate number of iterations. With an iterator, you =
=

don't know how many iterations are required until you've finished (you c=
an =

find out, but it's more work). So reading code that says "while there a=
re =

more elements do x" just seems more correct.

Dan.

-- =

Daniel Dyer
http://www.uncommons.org