[CS Technical Interview 6] Java and Object-Oriented Programming that gets you talking

A course where you understand the core concepts of Java and Object-Oriented Programming (OOP), and even train to explain them verbally in interviews.

(4.9) 22 reviews

499 learners

Level Basic

Course period Unlimited

Java
Java
oop
oop
Tech Interview
Tech Interview
Java
Java
oop
oop
Tech Interview
Tech Interview

Reviews from Early Learners

4.9

5.0

pray

100% enrolled

Wow... this is really so good...;;;; I need to save up money and buy everything in the roadmap.. I'm curious if you're planning to do any Spring lectures too.. I'll buy it right away..

5.0

karabiner

100% enrolled

The lecture pinpointed the key points, making it highly efficient for the time invested.

5.0

박상완 Sang Wan

55% enrolled

While preparing for Java developer interviews, I needed a systematically organized lecture, and this course was a great help. The detailed explanations of JVM structure, memory areas, exception handling, and other theories are memorable. This is a core summary lecture that can be directly applied in actual interviews.

What you will gain after the course

  • Java, Understanding Core Object-Oriented Concepts

  • The ability to explain verbally in technical interviews

  • Practical Workbook PDF to Prepare for Follow-up Questions

Have you ever had an experience like this 🥲 in an interview?

1. When answering with confused concepts

Interviewer What are the characteristics of object-oriented programming?
💬 Candidate It's the SOLID principles. First, S is...(omitted)...

This is a situation where the characteristics of object-oriented programming (abstraction, encapsulation, inheritance, polymorphism) and
the object-oriented design principles (SOLID) are confused.
This can give the impression that the framework of basic concepts has not been established.

2. Knowing only the "What" but failing to explain the "How" or "Why"

Interviewer: What are the characteristics of TCP?
💬 Candidate: It is a protocol that guarantees reliability.
Interviewer: What is the mechanism that guarantees reliability?
💬 Candidate: Uh... well... it's like... making sure it's transmitted safely... sort of...

This is a state where you only know the superficial definition and are not prepared to explain the principles.
If the 3-way handshake, sequence numbers, ACK, retransmission, flow control, and congestion control are
not connected as a single flow, you will inevitably get stuck on follow-up questions.

3. When you get stuck on basic questions

Interviewer: What is HTTP?
💬 Candidate: Uh... it's like... for sending and receiving data on the web...?

It is a very familiar concept, but when you actually try to explain it in a single sentence, the words don't come out.
This is not a lack of knowledge, but a lack of experience in organizing and speaking it aloud.


Knowing it is not enough. It only becomes a true skill when you can explain it in words.

🔥 So, this is how we've structured it.

Next-level, premium content for interview preparation

1⃣ CS Notes Organized Specifically for Interview Preparation

  • Concepts and principles that must be checked before an interview are gathered together and provided as lecture materials.

  • While building a solid foundation, it is structured so that you can keep coming back to it right until the moment of your interview.

  • It is not just a simple summary, but includes diagrams and easy explanations so that even non-majors can fully understand it.


Computer Architecture Lecture Material Example

2⃣ Appendix | Interview Practice Materials Provided

  • In an interview, the ability to explain clearly is much more important than simply knowing the information.

  • However, organizing and practicing on your own is a difficult and tedious task.

  • At the end of the lecture materials, we have included "answering in one or two sentences" training to save you the trouble of organizing it yourself.


Example of Database Lecture Appendix

3⃣ Preparing for follow-up questions,  Technical Interview Practice Workbook PDF provided

  • "Will this lecture alone really be enough for speaking practice?"
    After much deliberation over this concern,

    I have created a technical interview practical workbook.

  • It is designed so that you can practice speaking just like a real interview on your own.

  • You can find detailed information about the workbook's structure and how to use it in the workbook introduction video at the beginning of the course.

Operating System Workbook Example

4⃣ A course that keeps growing with a single purchase

  • This course is provided with unlimited access.

  • The content will continue to expand with new supplementary explanations and additional examples.

  • Even if the price increases as more content is added, students who have already purchased the course
    can access all content at no additional cost.

  • It is a CS guidebook you can return to and consult whenever needed.

💡 How to make the most of this abundant content

1⃣ Download the materials and learn the core concepts while listening to the lectures.
2⃣ Take your own notes on the important parts to create your own CS interview notes.
3⃣ Save them on your phone and review them briefly whenever you have a spare moment.

If you have an interview coming up and
are short on time → Lecture Materials Appendix [Interview Practice] quickly sharpen your interview senses.
If you have time → Complete your speaking practice like a real interview with the Technical Interview Practical Workbook.

🎯 Recommended for the following people

Non-majors, job seekers, or those preparing for a career change who are facing technical interviews and need to be able to verbally organize CS fundamentals.

CS majors who need to review and reorganize

I've studied it before, but
I don't know where to start organizing all that CS knowledge again

Don't open those thick textbooks
again.
We will clearly organize only the core essentials.

Non-majors who feel overwhelmed by CS

I'm preparing for a technical interview for the
first time, and I'm overwhelmed
not knowing where to start

By following the roadmap,
you can focus on learning
only the key CS core concepts..

Job seekers looking to change careers with limited time

Forget that, I don't have time.
I need to

quickly summarize only the CS topics that appear in interviews.

There are lecture materials and interview chapters that allow for
quick review
even on your own.

🔥 Reviews from students who experienced it first

A truly helpful lecture.
Already proven by 5,000+ students.

⭐️⭐️⭐️⭐️⭐️

1. A lecture where you can see how much the author has thought and agonized from the student's perspective (it seems the learner's flow of understanding was well-considered)
2. Easy to understand due to diverse visual materials and examples
3. When learning new knowledge, previously learned content is mentioned and recalled to connect information. As knowledge connects, the big picture begins to form.
4. The depth of knowledge is not shallow. I'm taking the Operating Systems course right after Computer Architecture, and the synergy is great.
5. It perfectly scratches the itch of wondering "why" & "why we use it."
ps. My apologies to the author, but.. it's a lecture I want to keep all to myself.

-'Operating Systems' Course Review

⭐️⭐️⭐️⭐️⭐️

Even though the lecture time is short, I really like how the important parts are explained clearly. Since it's mostly a theory-based course, I didn't expect SQL queries to be covered, but I loved how the basic syntax and writing queries were taught with step-by-step examples. After that, the sections on joins, normalization, transactions, indexes, data optimization, and security were excellent. While I haven't taken other paid courses yet, the last lecture appendix titled "Interview Practice" was great for self-study and practice as it provided actual questions and answers. The lecture time isn't too long if you stay focused, so I think I'll rewatch it a few times. Thank you.

- 'Database' Course Review

⭐️⭐️⭐️⭐️⭐️

The core content was explained so clearly and with such a logical flow that it helped me quickly organize my understanding of data structures. Thank you for the great lecture.

- 'Data Structures' Course Review

⭐️⭐️⭐️⭐️⭐️

Wow... this is seriously so good...;;;; I need to save up and buy the whole roadmap.. I'm curious if you have any plans to teach Spring as well.. I'll buy it immediately..

-'Java and Object-Orientation' Course Review

⭐️⭐️⭐️⭐️⭐️

This is a lecture where you can organize the key concepts of JavaScript all at once by setting aside about a day! It's great for a quick reminder before an interview👍



- 'JavaScript' Course Review

⭐️⭐️⭐️⭐️⭐️

As a non-computer science major, I was worried about how to study CS knowledge, especially computer architecture and operating systems. However, the content was divided into appropriate amounts, so I could learn without feeling overwhelmed, and it was great because it felt like getting private tutoring from an expert. I plan to take the operating system lecture as well, and I'm looking forward to it. Thank you!

- 'Computer Architecture' Course Review

🖐 Hello! Let me introduce myself! 🙇

As someone from a non-major background, I initially focused solely on algorithms and coding tests while preparing for my first developer job.
I gained some confidence and passed most coding tests, but I continued to fail at the next hurdle: the technical interview. What was the problem? It was the lack of CS (Computer Science) knowledge.

I understand the thirst for fundamentals (CS knowledge, programming languages, etc.) better than anyone. I built up my own know-how by digging through countless materials on my own, and eventually, after graduating from Seoul National University, I am working as a 🧑🏻‍💻 Kakao developer.

Since I was young, I have been more confident than anyone else in combining and restructuring various materials to create my own 'all-in-one summary notes.' This lecture is the secret notebook that contains all of that know-how and passion.

🚀 The sixth subject of the Fluent CS Series is Java & OOP.

  • JVM and Garbage Collection (GC)—you know the concepts, but can you explain how they actually work?

  • Multi-threading and synchronization—you've heard of them, but do you find it difficult to explain them in just a sentence or two during an interview?

📖 Curriculum packed with only the essentials gói gọn những nội dung cốt lõi

Here is the table of contents and key keywords you will learn in this course.

If there are any unfamiliar keywords, take this opportunity to master them once and for all.

  1. Object-Oriented Basics

    • Characteristics of object-oriented programming, SOLID principles, etc.

  2. Java Overview

    • Java features, JVM / Garbage Collector (GC), Reference types, Call by Value, static keyword, etc.

  3. Object-Oriented Programming

    • Java's OOP, polymorphism, interfaces and abstract classes, etc.

  4. Collections

    • Characteristics and various comparisons of List, Set, and Map

    • Comparison of various Sets (HashSet, LinkedHashSet, TreeSet)

    • Comparison of various Maps (HashMap, LinkedHashMap, TreeMap, ConcurrentHashMap)

  5. Multi-threading and Concurrency

    • Methods for implementing multi-threading

    • •synchronized keyword and volatile keyword, etc.

  6. Exception Handling and Other Concepts

    • Exception handling methods, exception hierarchy, serialization/deserialization, comparison of String vs. StringBuilder/StringBuffer, etc.

  7. Modern Java (Post-Java 8)

    • Functional interfaces and lambda expressions, comparison between collections and streams

  8. [Appendix] Interview Practice

    • Reviewing key concepts once more in a Q&A format

✏ Here is what we will cover

1⃣ Object-oriented design principles and application methods

  • Learn everything from the core philosophy of object-oriented programming, SRP (Single Responsibility Principle), to the SOLID five principles.

  • By comparing poorly designed code with refactored code, you will understand how to improve maintainability and scalability.

  • Through practical Java code examples, you can clearly learn the 'application methods' rather than just theory.

SRP explanation and code examples

2⃣ Easy explanation of confusing core Java concepts using diagrams and illustrations

  • JVM and Memory Structure Explains the JVM execution process and the roles of Stack/Heap memory areas easily with diagrams.

  • GC (Garbage Collector) Operating Principles You can solidify your understanding by learning the complex GC process through visual diagrams rather than abstract explanations.

  • You will learn in depth, along with diagrams, how the call by value method is reflected in actual memory states and code execution. phản ánh vào trạng thái bộ nhớ thực tế và việc thực thi mã nguồn thông qua các sơ đồ minh họa.

Examples of GC operation processes

Example of explaining JVM components

Explanation of the call by value principle

3⃣Multi-threading and Synchronization Strategies for Immediate Practical Use

  • Various thread creation methods implemented using Thread, Runnable, and ExecutorService

  • synchronized, volatile keywords' meanings and differences in operation

  • Learn how to safely access shared resources by comparing code execution results before and after synchronization.

Example explanation of the synchronized keyword

👀 Lecture Preview

If the video is frozen, please refresh the page :)

Explanation of Garbage Collector (GC)

All in One! A Comprehensive Summary of Essential Java Concepts That Are Often Confusing

Notes before taking the course

  • Format of provided learning materials: PDF

  • Prior knowledge of basic Java syntax is required.

Recommended for
these people

Who is this course right for?

  • A non-major who feels overwhelmed because it's their first time studying CS

  • Computer science students who need to organize CS concepts before a technical interview

  • Job seekers who are short on time ahead of a technical interview

Need to know before starting?

  • JAVA Basic Syntax

  • Learning becomes much easier if you have a grasp of basic operating system concepts like memory and threads.

Hello
This is yiyj10305235

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5,421

Learners

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Reviews

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Answers

4.9

Rating

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Courses

Education and Experience

  • Graduate of Seoul National University

  • Current Kakao Server Developer

    Course Introduction I am creating the "Fluent CS" series to help you articulate CS concepts during interviews. Course Philosophy Having started development as a non-computer science major, I understand the importance of CS...

Course Introduction I am creating the "CS for Speaking" series to help you articulate CS concepts during interviews. Course Philosophy Having started development as a non-computer science major, I...

Course Introduction

I am creating the
CS Speaking series to help you articulate CS concepts during interviews.

Teaching Philosophy

I started my development career as a non-CS major and went through a lot of trial and error while personally organizing everything from CS fundamentals to technical interviews. Based on the learning methods and conceptual organization know-how accumulated through that process, I create content that makes core concepts encountered in practice and interviews easy to understand through illustrations.
"I am creating the lectures that I needed back then."

Blog yiyj1030.tistory.com → Running a tech blog that simplifies CS, algorithms, and practical concepts. Contact yiyj1030@gmail.com

Blog

  • yiyj1030.tistory.com
    → Running a tech blog that simplifies and organizes CS, algorithms, and practical concepts

Contact

yiyj1030@gmail.com

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Curriculum

All

40 lectures ∙ (3hr 6min)

Course Materials:

Lecture resources
Published: 
Last updated: 

Reviews

All

22 reviews

4.9

22 reviews

  • happhuy2089님의 프로필 이미지
    happhuy2089

    Reviews 1

    Average Rating 5.0

    5

    100% enrolled

    It felt like it meticulously filled in the missing parts. I think other series would also be helpful to watch before interviews.

    • yiyj10305235
      Instructor

      Thank you for the course review. I hope this lecture isn't the end and that we can continue the learning journey together. I look forward to seeing you again in the next series :)

  • asd21123님의 프로필 이미지
    asd21123

    Reviews 11

    Average Rating 4.5

    5

    100% enrolled

    Wow... this is really so good...;;;; I need to save up money and buy everything in the roadmap.. I'm curious if you're planning to do any Spring lectures too.. I'll buy it right away..

    • tommy0419님의 프로필 이미지
      tommy0419

      Reviews 24

      Average Rating 5.0

      5

      100% enrolled

      I took this course to quickly review concepts. Overall, you covered everything well, which helped me review quickly. Thank you.

      • doitdoit님의 프로필 이미지
        doitdoit

        Reviews 30

        Average Rating 5.0

        5

        100% enrolled

        This is a lecture you can watch to grasp the major topics before an interview.

        • yiyj10305235
          Instructor

          Thank you for the course review. I hope this lecture isn't the end and that we can continue the learning journey together. I look forward to seeing you again in the next series :)

      • hungrylosemuscle님의 프로필 이미지
        hungrylosemuscle

        Reviews 22

        Average Rating 5.0

        5

        100% enrolled

        It's great for quickly organizing the overall concepts!

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