By Accident or By Design

While I do learn something new in life every day, it is rare that I actually learn something about Java.

Not to sound prudish or something... I learn new ways of doing things in Java, and find new libraries to use, and find innovative ways of using existing libraries, and innovate around algorithms and stuff every single day... Its just been a long time (I'd say about a couple of years or so) that I learned something new about the Java language itself. Its not even something sensational or mindblowing or anything... It just pleasantly surprised me today.

Enough preamble, I don't really need a justification for posting on my own blog, do I?

Consider an abstract base class

AbstractBaseClass

. This base class has a concrete implementation of a method

concreteMethod

. The concreteMethod is basically in the AbstractBaseClass because the implementation depends on data already available in the objects of AbstractBaseClass, and not really those that the ConcreteSubclasses need to worry about.

Moving on, there is a specific abstract subclass of the AbstractBaseClass,

AbstractSubClass

. This is an aberration of sorts, because all other subclasses of AbstractBaseClass are concrete... AbstractSubClass is not really that big an aberration, as it does have a few ConcreteSubSubclasses of its own..

So, where's the problem?

None, yet.

The problem arises when you realize that the implementation of concreteMethod in AbstractBaseClass is not really appropriate for the

ConcreteSubSubclassA

and

ConcreteSubSubClassB

, which are both concrete sub classes of AbstractSubClass. Wait a minute..., you realize... The implementation of concreteMethod is not really appropriate for any current, or future subclass of AbstractSubClass...

Which means that you have a concreteMethod in your AbstractBaseClass, which is perfect for all other concrete subclasses, except for concrete subclasses of AbstractSubclass, which need different handling per class for concreteMethod, which means that overriding concreteMethod in AbstractSubclass is not the answer.

How do you ensure that all subclasses of AbstractSubClass actually provide an implementation for concreteMethod, while maintaining the AbstractBaseClass implementation for all the rest (except those that need to override it anyways, stupid edge case...)??

<drum roll>

Apparently, it is legal to override a concrete method and erase the implementation, making it abstract, in AbstractSubclass, to enforce subclasses of AbstractSubclass to implement concreteMethod, as if it were just another abstractMethod, similar to some of the other abstractMethods in AbstractBaseClass.

...

...

That was it.

Have I managed to confuse someone?

I'll try and maybe draw a figure or something tomorrow... Maybe some code samples might help...

Then again, maybe the idea won't seem so awesome, after I've paid off a bit of my sleep debt, so don't hold your breath much....

My company started out this cool new service called YourBillBuddy.com

For starters it is targetted at the Indian Mobile Phone users market. You can upload your mobile bills, and it analyses the bills to figure out if there is a better plan that you could switch to, either in your same provider or in another provider.

It also uses some really cool graphs and stuff to convince you of this.

I wish I had been on the team that developed this, but the idea really rocks!

Click here to find out more, and register.

In the last week or so, I've been tweaking things with my site (http://www.ujjwal.net/), with the result that I'm now at #1 for the Google search "ujjwal". I also have high results on some other engines (notably Lycos), while I don't figure anywhere in the picture for some others (sadly, Yahoo!).

It is said that Search Engine Optimization(a.k.a. SEO) is a pretty difficult and unpredictable task, and they say that seeing results in times as less as a week is almost impossible.

What have I been upto?

Several things:

• Google Sitemaps
  
• Adding keywords and descriptions meta-tags to my pages (some of them already had it)
  
• Publishing my website URL on various profiles that I have, including Opera, Orkut, Blogger among others.
  

I'm still wondering which among these is responsible for improving the ranking of my page in the search results. Notably, my PageRank on the Google toolbar still says 0.

I'm still working on improving the content on my site, and retaining the #1 ranking as long as possible.

Please let me know of other tips to improve search engine rankings. I'll keep my efforts updated on this blog.