Whilst it may be true that some very experienced developers would find it an insult to be asked to perform such a simple task in an interview. I personally would find it more of an insult if my full coding ability could be proven by any question in an hour long interview.

The point of the interview is to gain insight into the candidate and the company. This is all based on the types of questions asked, the way they are asked and the way they are answered. The good candidate will be the one that thought the questions were great and that answered them the way the interviewer wanted them to. This will provide a candidate who is on the same level as the interviewer which is far more important than defining any level of coding ability.

One thing to remember however, I don’t care if you have 2 years experience or 20 years, one day, you might just have to reverse a string.

Robin

http://www.codinghorror.com/blog/archives/001008.html

Most (all?) people would write a shuffle on their own instead of reusing the JDK version.

To explain my comments about developers reading blogs and reading articles. Several people share my experience and opinion.

See for example

http://www.codinghorror.com/blog/archives/001002.html

and

http://blog.red-bean.com/sussman/?p=79

“There are two “classes” of programmers in the world of software development: I’m going to call them the 20% and the 80%. The 20% folks are what many would call “alpha” programmers [...] The 80% folks make up the bulk of the software development industry.”

“BTW, if you want to work for a financial software company in Tokyo just ping me!” Ah, Tokoyo :-)

Let me add a (peaceful) comment about my own practice.

I did the string reversal interview too and really what I appreciated the most was coding with someone during the interview. If you hire someone to do some development, it’s hard no to see him develop. But Reginald says it better than me: http://weblog.raganwald.com/2006/07/hiring-juggler_02.html,...

Right now, I have switched to another simple exercise, which I took from “daily life”. Write a function which will return a list of pairs of currencies from a list of currencies (financial software,…).
And I give examples:

List() -> List()
List(“EUR”, “USD”) -> List(“EUR/USD”)
List(“EUR”, “USD”, “JPY”) -> List(“EUR/USD”, “EUR/JPY”, “USD/JPY”)

And I ask people to develop that using JUnit in a TDD fashion: first we write the test, then the code. If they don’t know JUnit, I provide examples and they fill in the blanks.

Here are my observations so far, which are aligned with yours, Stephan:

-it is the only way to know if someone is really a programmer or not. I have been very badly surprised by people who should have a good development experience based on their resume and who were not able to produce some working code in a reasonable time. For example, they can talk about the difference between an interface and an abstract class during the interview and not know how to use the List interface in Java.

-very few people I’ve met (since we’ve began the interviews two months ago in Tokyo) can develop the last case. We usually have to stop after the second test case because of time

-this shows a lot about programming habits: naming conventions, exception handling, code layout, data structures, knowledge of the language (java: imports, generics,…), etc. I am also astonished by the number of people using Eclipse every day (that’s what they say,…) and not knowing shortcuts or refactorings

-I would also be very happy to see someone come up with a recursive solution because I personally find it quite elegant. Never happened before,… Let alone talk about tail-recursion! Even though, you can be a good developer without this (but I suspect that excellent developers would at least mention the option)

-This is a very time-consuming exercise in the recruitment process. I would like people to do the exercise and perform better. Watch them agonizing over a List interface is not my greatest pleasure in life. So right now we resorted to a silly java questionnaire to try to bring more relevant candidates to the table. If you have better ideas?

-Even if they don’t perform so well, the candidates always learn something out the exercise and I try to share with them as much as I can. We’ve had very good feedbacks about the interviews so far.

So my conclusion is: please, let me code during my next interview! I may not know if StringBuffers are really optimized by the JVM under specific circumstances but I will just have the opportunity to do something I love. And I hope it will show!

Eric

PS: BTW, if you want to work for a financial software company in Tokyo just ping me! You can come up with a perfect solution coded during a one-week break, I’ll be happy to discuss it. And the fact that you read this blog is your first “good point” on my list!

Well there is, but obviously you haven’t read the post about unit testing, fringe cases, error handling and interfaces.

Compressing your comments leaves me with: “… dumb … awful … dude … the problem is the interviewer … your arrogance … clearly arrogance … hate … employeed smarty pants … lack of good interviewers … ” Clear pattern? Go figure.

Peace
-stephan

I also read the original post and your replies. And there is a clear pattern in all of your responses to anyone that doesn’t think this is a useful exercise.

It’s an awful interview question, even if it’s just 5 seconds of the interview.

Reading the actual post would help though. Most of my interviews are 1h to 1.5h and sometimes 15 minutes of the interview is about reversing a String.

“Real story, I get the call for the interview, spend a few hours reviewing and brushing up on my project mangement ideas, design patterns and j2ee technologies and get asked to write a reverse string implementation for a Senior Developer position.”

This happened to you? They only asked the string reverse question? Nothing else? I wouldn’t like to work for them.

“I’ve been developing for about 12 years.”

Then it shouldn’t be a problem for you to write the method.

“Yes, everyone takes your comments out of context.” Yes, obviously, just like you do. Most of my interviews are 1h to 1.5h and sometimes 15 minutes of the interview is about reversing a String. The posts are about interviewing and about one detail of a longer interview, asking a development source code question. And which I wrote several times that this is just the beginning and “From there it’s an open field. You could ask the candidate to write a JUnit test for his reverse method. Not only can he show how to write a unit test, but what he considers as test cases (””, null, “A”, “Even”, “Odd”, ….).”

But in your comments this somehow mutates to: “Discussing a recursive solution for reversing a string demonstrates your arrogance and nothing about a programmers programing prowess.”

“Again, if a reverse string implementation question is your best interview material, dude, the problem is the interviewer.” Most of my interviews are 1h to 1.5h and sometimes 15 minutes of the interview is about reversing a String..

“And the answer to this question too can be google’d.”

Reading the actual post instead of ranting and insulting people, you would have found “Which is quite as good, because googling in reality will help him find the JDK solution.” But obviously you haven’t read the post. I hope you give more attention to requirements you implement than reading blog posts.

Peace
-stephan

I’ve been developing for about 12 years and I meet interviewers, like you, asking me to do a reverse string implementation. Real story, I get the call for the interview, spend a few hours reviewing and brushing up on my project mangement ideas, design patterns and j2ee technologies and get asked to write a reverse string implementation for a Senior Developer position.

Again, if a reverse string implementation question is your best interview material, dude, the problem is the interviewer.

And the answer to this question too can be google’d. Clearly, it’s not a good question for anyone but a entry level candidate.

On a more serious note, there are studies which show that most developers don’t read blogs and don’t read articles. Go google.

“As someone who’s been on both sides very recently, I’ve determine that there is a lack of good interviewers.” Self insight is a good thing. Yes, some of the interviewers get personal and insulting.

Peace
-stephan

And clearly arrogance isn’t too strong a word as you’ve already determined that “very few” know about stringbuffer reverse and “few” read blogs and articles. As if you’ve inteviewed most. The most you can say in this regard is most of the people that you’ve interviewed didn’t know, but how many people is that ? I suspect, most college CIS students can answer this question if provided in the proper context.

I’m about tired of employeed smarty pants talking and writing about interviewees. As someone who’s been on both sides very recently, I’ve determine that there is a lack of good interviewers.

good ideas. I’ve also experienced “It’s a bunch of WE did this, or OUR team did that.” where it’s hard for a novice interviewer to go on and dig deeper. As you said, what role did he fill, what did he really do? Sometimes people claim to have experiences in lots of technologiies from a project where in the end they only put the HTML together.

Someone with good speaker skills can impress you during the CV and projects talk, it’s much harder for someone to talk you over with some code. And I had the same experience in the past: people with lots of projects knowledge who couldn’t write or discuss code. Or who got very angry when I criticized them for some code they wrote (They need to defend their code, and be enthusiastic about what they do, but don’t get angry).

The idea with the code away assignment is a good one. I think about that one and perhaps try it in the future, when I can adapt our interview process accordingly.

“With google stomping the market it’s hard enough as is.” And in Germany after 2 years of economic rise I have the feeling, most good people already have switched jobs who wanted to. Hard to get good new ones to interviews.

Thanks for your contributions.

When you just talk about past experience, you often miss out on what roles the person performed. It’s a bunch of WE did this, or OUR team did that.

Often I have found that charismatic and boastful shine during the experience yak, no matter their development prowess. So you lose the modest and quiet, but skilled programmer.

Your example is an excellent place to start an interview. It helps you with a sniff-test first of all (you would surprised how many people who are certified 8 year ‘veterans’ don’t know what a HashMap is) – And, it can start interesting TECHNICAL conversations. Your looking for an engineer, a technician, a person who loves the code. This type of person won’t mind for a second geeking out with you over even the simplest piece of code.

I recommend a step further though. We do a 45 minute walk away code assignment where we have the candidate fill in a somewhat trivial implementation. Then we come back, run some unittests on it and chat about design decisions and stylistic choices. Really, it doesn’t matter if it runs, it’s the conversation that matters.

I feel like you know this, but, other’s don’t, and let them be. They can hire the unqualified. With google stomping the market it’s hard enough as is. I can send Jonathan plenty of folks who can talk his ear off – Just don’t ask them to code anything.

Those who say “what a silly example” don’t really get it, IMHO.

Some examples:

(a) I once saw Stuart Halloway show a stacktrace (in a talk) and wonder out loud if he could talk for an hour on that stacktrace. I bet he could. Would you pay to hear James Gosling talk about reversing a string for 15 minutes? Jonathan might not; I would.

(b) I don’t know much about art, but I’ve learned that the still-life paintings (e.g. an apple, a fruit basket) are not so much about the immediate subject but rather what the artist has done with it. The reaction should not be “it’s a silly apple” but rather an appreciation the way the subject was handled. Would you pay to see Rembrandt or Picasso draw an apple? Many people have.

(c) Blues music is based on traditional chord structures and licks (melodies). Just like the apple, these aren’t always new. The point is what the person can do with them, and the style that surrounds them. A good interview candidate should be able to talk about reversing a string just as a good guitar player should (happily) play a Chuck Berry riff (w/ his or her own style).