Technical interview questions

Hello everyone, Javarashovtsy! It just so happened that I recently had an interview and would like to tell you what questions I was asked, assuming that the position is Junior ++. Those. not yet middle, but not green June either. So, the interview went like this

1. JavaCore
2. OOP
3. REST
4. Database.
5. The tools you use.

JavaCore

• At first, I was asked to draw a hierarchy of interfaces for Collections (it was not difficult, there are only a few of them ( Collection, List, Set, Queue, Map).

• What is the difference ArrayListand LinkedList(this is one of the most hackneyed questions and answers on the Internet is just darkness).

  We discussed the speed of query execution in them and what is the difference between the sheets.

• Question about class Object. What are his methods, what do they do.

• Reflection. What does the getClass(). Very interesting question, take a look at it. Especially about how to get everything about the class, even if there are private methods or variables.

• Asked about multithreading. Weak, as I think, so tell how you understand what multithreading is. What is needed to start a new thread. Realistically, if you are level 20+, then these questions will seem ridiculous to you.

• What can you say about Stream. This is not about Java 8. It means input and output streams. Like basic interfaces, what they are (character and byte). For understanding, no specifics.

• Exceptions. Here, again, they asked to draw a hierarchy of exceptions, which are, which ones checked, and which ones unchecked. What to do with Runtimeexceptions. Name the most frequently hit ( NullPointerException).

• The question is what should be done with checkedexceptions (thrown further or processed - both are understandable).

OOP

• What is OOP in a nutshell?

• What other programming paradigms are there? How are they different from OOP?

• What are the main principles of OOP (inheritance, polymorphism and encapsulation)? Tell about each of them. So far, everything is abstract, not tied to any language.

• The task of understanding systems design: there is a Horse and a Bird. You need to get Pegasus. principle "has a" and "is a"

REST

• What is REST. Wikipedia talks about it very cool. In fact, Wikipedia articles are enough for review.

• HTTP. There are also common phrases here. His methods, for what each of them.

• HTTP status codes. What five parts to divide into, tell us about the most famous (200,204,404,500,501). Why are they. They also asked about 401 and 403. But I didn't know them. They said important.

Database

Here I said that I know MySQL. Told about three normal forms. He told about Joins, which are and drew the intersection of areas in which different joins are used. He talked about how I understand a relational database. Don't forget about MongoDB - it's a NoSQL database. After some time I will write about it.

Other tools

Here we went through my resume. It was written to me that I use Maven / Gradle for building, I use JIRA for tasks, git, Docker, Swagger. For Continuous Integration - Stash, Bamboo, Puppet. For testing JUnit , Mockito, JMeter. I could forget something, so if you are interested, ask in the comments and I will try to answer. This was the first part of the interview. Now I'm waiting for the results and if so, there will be a second part. I will write about it as soon as possible. Anyone who liked the article and was useful - put "+". Write in the comments. See also my other articles:

• Test task: "Write an Interpreter in the BrainFuck language"

• Test task "Image Comparison"

• Java - faster, stronger and higher! Salaries of Ukrainian programmers

• Success story after 1.5 years from the start of training

• How to create an executable jar in Intellij IDEA / how to create jar in IDEA

• How to find a job? CV distribution

• professional burnout. How to resist?

• English for IT and for interviews

• Command pattern in your own words

• Singleton pattern in your own words

• Help, I need some motivation!