Re: Iterating over an array style question

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 24 Nov 2010 14:45:47 -0500

Message-ID:

<4ced6b5f$0$23762$14726298@news.sunsite.dk>

On 24-11-2010 08:16, Eric Sosman wrote:

On 11/24/2010 1:16 AM, Alex Mentis wrote:

Leif Roar Moldskred wrote:

Daniel Giaimo<dgiaimo@gmail.com> wrote:

how
do you feel about the following code for iterating over an array?

int[] arr = {1, 2, 3, 4}

for(int i=arr.length; i-->0;)
{
System.out.println(arr[i]);
}

I don't like it. Somewhere, I picked up a rule about how good code
shouldn't rely on the difference between the post-increment and
pre-increment operators.

There's also a school of thought that generally believes that Boolean
tests shouldn't have side-effects.

Who are the teachers in these "schools," and why haven't they
been fired yet?

BufferedReader rdr = ...;
for (String line; (line = rdr.readLine()) != null; ) // BZZZT!

That is not very nice code either.

BufferedReader rdr = ...;
String line;
while((line = rdr.readLine()) != null)

is what I will consider the idiomatic solution.

Pattern patt = ...;
Matcher match = patt.matcher(...);
if (match.matches()) // BZZZT!

That construct is very common.

JDBC ResultSet is similar.

... and so on, and so on. Sounds like a silly school.

As it often is, then it is a matter of balance.

No side effect is better than side effect.

No temporary variable is better than temporary variable (in this
case - can not be generalized).

It is a choice.

Arne