Re: get hexadecimal hash string for a number

From:

Lew <lewbloch@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 18 Sep 2012 10:10:00 -0700 (PDT)

Message-ID:

<a7e8fd59-4a4a-499e-9366-bedad1d5e097@googlegroups.com>

Magnus Warker wrote:

I want users to register on a site and send confirmation emails to them.
These emails should contain a link like this:

http://myurl?registration=E4AC4BD4

Here, "E4AC4BD4" should be a unique string. My idea for such a string is
just to hash an integer, i. e. the internal database key for the
registration record.

However, I actually don't know how to get such a hash. I tried BCrypt,
but this produces hashes built out of characters that I would not want
to be in a URL, e. g. commatas and that.

I would like to have a string like this:

- hexadecimal only
- fixed size, e. g. always n characters, independend of the integer

Can you help?

First of all, hashing a unique integer is silly. It's already unique!

If you have a reliably unique, stable integer ID, you don't need to hash it!

Just use the value.

Got that? Good, because an internal database ID is not reliable.
It's *internal*! It's not meant to be used externally!

Got that? Good, because the database record has (or you're not doing it
right) an external unique key, one based on visible attributes. You could
hash that key.

Or you could perhaps use
http://docs.oracle.com/javase/7/docs/api/java/rmi/server/UID.html

You'll want to store that UID with the registration record.

First and foremost google around for hash codes and how to use them.
Your lack of understanding will screw you otherwise.

--
Lew