Though everyone loves unit tests and everyone agree with benefits they bring in, when the time comes to write them, you will see a lot of excuses, even from some of the more experienced and senior developers. At the heart of the problem of not writing unit tests or enough unit tests they are two things, first is time pressure i.e. you don't have enough time to complete coding forget about writing unit tests. This problem comes due to erroneous estimation i.e. only estimating time for coding and not including unit testing as part of development. This is also our first excuse, so we'll see it in a short while. The second reason is laziness and ignorance i.e. you don't know to write unit tests but don't put enough effort to learn the tips and tricks. In this article, I have shared some of the most common excuses given by programmers for not writing unit tests.
How many characters is allowed on VARCHAR(n) columns in SQL Server? How much memory VARCHAR variable takes in disk?
One of the frequently ask SQL questions in any programming interviews is what is the difference between VARCHAR and CHAR data type in SQL? particularly when your project is using Microsoft SQL Server. You might have seen this couple of times, but given its popularity, nowadays people are asking this question differently e.g. they will ask you how much space a column of VARCHAR(2) data type will take? How many characters can it take? How do you minimize the space? Is it better to use a CHAR variable instead of VARCHAR(2) and why? These are some of the really interesting question and more meaningful than classical SQL questions like the difference between char vs varchar data type question.
This is one of the many interesting multi-threading questions I have shared in my post 50 multi-threading interview questions. Yes, you can make an array volatile in Java, there is no problem with that, neither compiler will flag any error not JVM will throw any exception but the tricky part is why you want to make an array volatile and what is the effect of making an array volatile in Java? In order to answer this question you must be familiar with both volatile modifier and Java memory model, otherwise, it would be difficult to answer, and that's why it's also one of the trick questions from Java interviews. Before answering this question in detail, let's first revise what is a volatile keyword in Java and what kind of guarantee it provides in the context of multithreading and concurrency.