Cache Implementation in JAVA

A lot of us heard the word cache and when you ask them about caching they give you a perfect answer but they don’t know how it is built, or on which criteria I should favor this caching framework over that one and so on, in this article we are going to talk about Caching, Caching Algorithms and caching frameworks and which is better than the other.

The Interview:

"Caching is a temp location where I store data in (data that I need it frequently) as the original data is expensive to be fetched, so I can retrieve it faster. "

That what programmer 1 answered in the interview (one month ago he submitted his resume to a company who wanted a java programmer with a strong experience in caching and caching frameworks and extensive data manipulation)

Programmer 1 did make his own cache implementation using hashtable and that what he only knows about caching and his hashtable contains about 150 entry which he consider an extensive data(caching = hashtable, load the lookups in hashtable and everything will be fine nothing else) so lets see how will the interview goes.

Interviewer: Nice and based on what criteria do you choose your caching solution?

Me:huh, (thinking for 5 minutes) , mmm based on, on , on the data (coughing…)

Interviewer: excuse me! Could you repeat what you just said again?

Me: data?!

Interviewer: oh I see, ok list some caching algorithms and tell me which is used for what

Me: (staring at the interviewer and making strange expressions with his face, expressions that no one knew that a human face can do :D )

Interviewer: ok, let me ask it in another way, how will a caching behave if it reached its capacity?

Me: capacity? Mmm (thinking… hashtable is not limited to capacity I can add what I want and it will extend its capacity) (that was in Memind he didn’t say it)

The Interviewer thanked Me(the interview only lasted for 10minutes) after that a woman came and said: oh thanks for you time we will call you back have a nice day This was the worst interview Mehad (he didn’t read that there was a part in the job description which stated that the candidate should have strong caching background ,in fact he only saw the line talking about excellent package ;) )