CompSciPrompt's Blog

hashCode()

compsciprompt — Thu, 08 Apr 2010 21:56:10 +0000

I had always overlooked hashCode() until NOW!

I saw its usage for the first time in the put() method of HashMap. SO, basically, hashCode() calculates the hash of an object. Since we have the handle of the reference, we take that address and calculate the hash. And therefore, every object has a “distinct” hash code which does not solve the purpose. But, classes like String, Integer which like other classes inherit from Object override hashCode(). And this property is used to identify whether we have duplicate elements in the list, set, whatever…

Another very very simple/small concept that I should have known before but ….!

Supported values for @SuppressWarnings

compsciprompt — Wed, 10 Mar 2010 21:16:17 +0000

http://www.breakitdownblog.com/supported-values-for-suppresswarnings/

A handy article

JAVA Enum

compsciprompt — Wed, 10 Mar 2010 21:10:52 +0000

I never worked with enums before but realized today that whenever the compiler comes across the enum keyword, it makes a JAVA class corresponding for that. [http://www.baskent.edu.tr/~tkaracay/ders/prg/java/api/java/lang/Enum.html]

And also, each constant corresponds to an object of Enum class.

Ant

compsciprompt — Wed, 10 Mar 2010 05:29:31 +0000

I have always wanted to know what “Ant” is and how it is compiled/executed. Though I had a fair, basic idea of what it is, I was still curious for a step-by-step procedure. I googled and found this:
http://techtracer.com/2007/04/16/the-great-ant-tutorial-a-great-jump-start/

Just another “useless” post for people reading it. (I know I should have known this long time back! )

ThreadLocal

compsciprompt — Tue, 09 Mar 2010 20:58:00 +0000

This class as written in the javadoc (http://java.sun.com/j2se/1.4.2/docs/api/java/lang/ThreadLocal.html) maintains
thread’s local state. Good enough. But how?

The code I was reading had

private static ThreadLocal tl= new ThreadLocal(){
public Object initialValue() { //doSOmething }
}

And tl was as class member in the class. Isn’t that surprising that it is
1) static and
2) maintains each thread’s local data ?

After searching I found a simple article [ http://javaboutique.internet.com/tutorials/localdata/ ]
explaining ThreadLocal maintains an internal HashMap.

I did confirm after looking into the source code of JAVA too.

Maybe it was obvious for most of the JAVA devs but I found it interesting.

Memcached

compsciprompt — Sun, 07 Mar 2010 08:50:58 +0000

I am a bit late to comment on Memcached. I have been hearing this term since last 2 months. It has been actively used by almost all the internet companies. But, I never understood, how it worked from developer’s perspective.

Finally, I invested some time digging through it. And, this is your ONLY destination (to get the very basic idea of it):
http://www.majordojo.com/2007/03/memcached-howto.php

Another important conceptual blog on “how to use session with Memcached” :http://dormando.livejournal.com/495593.html

Treat!

compsciprompt — Mon, 01 Mar 2010 07:55:03 +0000

I moved into my new apartment (Mcguire apartments) in Seattle yesterday (the penultimate day of February 2010). It is pretty good. So, me and my room mate went for shopping to Walmart/Indian grocery store. Man, it is tiring!
It took us precisely 10 hours (that is including traveling and eating). It took us nearly 4 hours to cover Walmart, the beast.

We booked zipcar for the entire day. Some severe traffic rules that I broke:

Drove opposite to the traffic flow (in a one way lane)
Took a U-turn on a road having speed limit of 50 mph! (That was horrifying. Sorry, DMV. )

Nonetheless, I treated myself with 20$ Sony headsets and a wireless G router. Yeah, those are not at all expensive but still I am feeling proud
[A few of my friends would again think that I am nerdy. My fault that I could not show them the real nerds ]

Amazon.com

compsciprompt — Mon, 01 Mar 2010 07:38:43 +0000

I recently joined Amazon in Seattle (after graduating from UC, Irvine). Needless to say, it was a long procedure!
Nonetheless, I joined the Payments Platform team.

In terms of technology, I must say Amazon is a step ahead in terms of large scale distributed systems/ cloud computing platform. Yeah, it is true that “Necessity is the mother of invention”! So much code they have churned out, it is unbelievable!

I will keep web logging if I run into real interesting technical issues.

Till then keep coding!

Google || Buzz || Not cool!

compsciprompt — Mon, 22 Feb 2010 03:24:02 +0000

I have been a Google fanatic since 2004. And I have always loved their products. One of the reasons is that they keep innovating and that is what keeps me interested in them.

But, for the first time, I believe, Google has got something wrong with their launch of ‘Buzz’. The reason is they are trying to catch up with FB/Twitter (or rather mimic them). And when one tries to mimic some one, you tend to ‘try’ to keep up the pace with your competitors and you never innovate. (And that is the syndrome MS is experiencing. WEB was NEVER their domain but they ALWAYS try to match Google and you all know where they stand – Be it search/maps/mail/… )

I have my own reasons of hatred for Buzz: I don’t want ‘social networking’ attached to my personal/professional email account. It distracts me (therefore, I have turned it off). If I want to spend some time on it, I would rather log onto FB.

They are doing an amazing job in strengthening their search (more even after acquiring Aardvark) but I guess they should not invest their resources in social networking (Orkut being another crappy product).

No SQL movement!

compsciprompt — Thu, 14 Jan 2010 19:46:52 +0000

I have been trying/figuring/analyzing what this “NoSQL” movement is. Why are people moving away from RDBMS?

There are good reasons for it. I have been figuring out cassandra which facebook uses internally. I installed it on my windows machine (yes, it was a pain to install since the Read me file had all Linux commands/setup) and could successfully run on it!
I am going to write on how to get started with cassandra soon.

But, before that, I would suggest first to understand why RDBMSs should be ruled out. What is the need for it?
I came across this article: http://www.vineetgupta.com/2010/01/nosql-databases-part-1-landscape.html
It at least helped me a lot.

Another good article on understanding design/architecture of scalable distributed key-value data stores:
http://project-voldemort.com/design.php

Please leave a comment for a discussion (if you want to). I am always eager to learn/share technical conversations!