Re: Which scope for variables being used in a loop?

From:
"Manish Pandit" <pandit.manish@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
2 Feb 2007 19:00:49 -0800
Message-ID:
<1170471649.515339.321440@k78g2000cwa.googlegroups.com>
On Feb 2, 6:42 pm, "bugnthecode" <bugnthec...@gmail.com> wrote:

Hi everyone,

I've been working on an application for work and I'm using a library
provided by someone else. I'm now running into a problem where I'm
running out of memory under certain circumstances and have begun
tracing the problem. Anyway, this made me think about the way I've
coded some of my for loops. Take for instance the following snippet:

public void printCustomers(List<Customer> customers) {
 String customerName;
 String customerPhone;
 String customerLocation;
 for(Customer customer : customers) {
  customerName = customer.getName();
  customerPhone = customer.getPhone();
  customerLocation = customer.getLocation();
  System.out.println(customerName+customerPhone+customerLocation);
 }

}

Now my original thinking was that I would declare the strings outside
of the loop so that I'm not re-creating a reference each time through
the loop; I would just keep re-assigning it. Then I started to think
that maybe this wasn't doing as I expected, and the realized that
those 3 strings stay in scope until the end of the method meaning the
locations would be unavailable to the gc until the method was finished
processing. In the above snippet that really doesn't matter, but what
if I had much more code below the loop.

So my question is which way would be better on memory or performance.
Which is better coding style if performance and memory usage are
negligible either way?

Thanks in advance for your help.
Will


In this case, the variables are allocated on the stack, as they are
"local". I do not think this could lead to out of memory (unless the
collection is gigantic). Personally I never like the idea of declaring
variables within a loop, and have not seen a lot of instances where it
is done.

-cheers,
Manish

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