Graphs are used to represent enourmous number of real-life applications. Basically graphs contain vertices(nodes) and edges(lines that are connecting nodes). Edges may have a direction, or may exist without directions. Following figure is a simple example of undirected graph with 5 vertices.

It took a while to finish up this book, since it contains so many interesting topics. I would strongly recommend to service developers(especially the one who work with microservices), QAs, Infra and Engineering Managers. The books covers wide range of topics: Jenkins, Docker, Docker Swarm, Ansible, CI/CD, Automated Acceptance Testing.

It has become quite common that many companies provide hobby clubs among their workers. My current company also allows us to organize the hobby clubs. Company even provides 20’000 KWN (around 20$) per month, for us to enjoy the hobby club. As I have mentioned in my previous blog about TicketMonster it had a same cultural program. It was good experience for all members of the club to work on lego blocks. Members have tried really hard, and we really had a good time while making lego together.

The synchronized keyword ensures that only a single thread can execute a method or block at one time. It should not be confused with a mutual exclusion concept, that prevents an object from being seen in an inconsistent state by one thread while it’s being modified by another. Proper use of synchronization keyword guarantees that no method will ever observe the object in an inconsistent state.

Exceptions improve a program’s readability, reliability and maintainability. Basically there are three kinds of throwables: checked exceptions, runtime exceptions and errors. The main rule of using checked exception is this: use checked exceptions for conditions from which the caller can reasonably be expected to recover. When the checked exception is thrown, the caller forced to handle the exception in a catch clause or to propagate it outward(forward the exception to upper caller).

Quite simple but interesting problem. First I have been thinking how to solve it, I was considering to apply stacks to hold the substrings while I’m flying around with start and end indexes. Then I have realized that I don’t actually have to show the longest substring. I just have to show the length of the longest substring.

Here I try to put up some of the usefull git commands. Refer to it whenever quick check is needed.

Last time when I read the book Effective Java I met that example about generics from Item-28. Authors have introduced quite a good example with Chooser class, where they are trying to convert it to generic from non-generic class. This time when I’m reading book again I met this example and decided to put it here.

I would like to share my experience working as a developer at TMon (TicketMonster), one of the top Korean E-commerce company. Originated back in 2010 by five guys as a startup, where only two of them were developers. I think the story of TMon can be considered one of the successful stories. Even though I haven’t worked for long (1 year and 13 days saying exactly) to judge TMon. I can tell “it is good place for Developers” (<– for TL;DRs)