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Tuesday, 2 June 2009
By Steve Schnepp on Tuesday, 2 June 2009, 08:00 - database
Everyone is unanimous that database normalization is considered a Good Thing.
But it usually comes with a cost : writing queries can be very tedious since you always have to join many tables together to be able to retrieve useful human data from all those reference tables.
Monday, 1 June 2009
By Steve Schnepp on Monday, 1 June 2009, 17:38 - java
It seems that comparing two objects isn't as a simple task to do as it seems at first.
My concept for smart comparison still holds, but is completed perfectly with the How to Write an Equality Method in Java article posted on Artima soon after mine[1].
2 main points that you have to be careful to (Others are also detailed in this article) :
hasCode() has to be redefined usually since otherwise the
equality contract on Object.hascode() would be
broken.equals() has to take an Object as parameter since
overloading in Java is resolved by the compile-time type of the argument, not
the run-time type.I just got bitten by the second one, but not much (yet) since I mostly rely on compile-time overloading. My purpose here was only to compare objects either to constants or to simple variables. But in the generalization I would certainly have overlooked this and be bitten much more deeply.
[1] But as much as I wished it to be, it is not related :-)
Friday, 29 May 2009
By Steve Schnepp on Friday, 29 May 2009, 08:00 - general
Perfection is attained by slow degrees; it requires the hand of time.and Antoine de Saint-Exupery completed
Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away..
As concluded by Pascal, I made this letter longer than usual because I
lack the time to make it shorter
, a good and terse article
is therefore much more difficult to achieve. Therefore
Presentation Style Blogging may be a false good idea.
Tuesday, 26 May 2009
By Steve Schnepp on Tuesday, 26 May 2009, 08:00 - java
In Java, comparing things can be quite tricky. Comparing them with a simple
== only compares the references, and for example 2 strings could
be the same without being the same object. You have to compare
them with the equals() method. Now the infamous
NullPointerException (NPE) shows its ugly head when the first object to compare
is null.
Tuesday, 19 May 2009
By Steve Schnepp on Tuesday, 19 May 2009, 08:00 - database
When you just decided to use Surrogate Keys, another problem arises : which value should I use ? It seems to be a very simple problem since the key now is completely in isolation in your application and is not related to any data. The choice is quite bonding, since a change means that every value has to be changed, and you did not let this key leak outside the database did you ?
The keypoint here is isolation. Many differents kinds of isolation are available, and soon you will be able to make a informed decision.
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