Timeline

299 posts written so far.

2026 (7) 2025 (17) 2024 (16) 2023 (23) 2022 (17) 2021 (18) 2020 (34) 2019 (70) 2018 (97)

2026 (7)

When Subagents Aren't Enough: Claude Code Agent Teams

Claude Code Subagents: How Is Work Divided and Processed?

February 22, 2026

Beyond Prompts and Context: Harness Engineering for AI Agents

February 15, 2026

I Only Compressed CLI Output, Yet Tokens Dropped by 80%?

February 08, 2026

Why Did OpenClaw Suddenly Become a Hot Topic? (feat. Agent Runtime)

February 01, 2026

Five Critical Risks of Powerful AI That Anthropic's CEO Warns About: Reading 《The Adolescence of Technology》

January 31, 2026

Building Custom AI Agents with the Claude Agent SDK

January 09, 2026

2025 (17)

Cursor vs Claude Code: How to Choose the Right AI Coding Tool

December 30, 2025

AI Agent Skills: How to Create and Use Them

December 28, 2025

Claude Code Settings Files: How to Separate Shared Rules from Private Configuration

October 17, 2025

Why You Should Run /init First in Claude Code

October 04, 2025

JDK 25 LTS Release Notes: Key Changes at a Glance

September 19, 2025

How to Manage Claude Code Context and Reduce Token Usage

August 25, 2025

Context Engineering: The Next Step After Prompt Engineering

How to Connect MCP Servers to Claude Code and What to Watch For

Building an LLM API with Spring AI

How to Install Claude Code and Run It for the First Time

What Is Vibe Coding?

Kotlin Scope Functions Compared: let, run, with, apply, also

February 14, 2025

Kotlin Error Handling and Coroutine-Based Failure Resilience

February 08, 2025

Kotlin Coroutines: Concepts and Practical Usage

February 05, 2025

Kotlin Null Safety and Functional Programming

January 27, 2025

Kotlin Class Design and Type System Usage

January 13, 2025

Kotlin Basics: Syntax and Core Concepts

January 05, 2025

2024 (16)

Spring Boot 2 to 3 Migration Checklist: Breaking Changes You Must Address

November 23, 2024

The Optimistic Future Dario Amodei Described in 《Machines of Loving Grace》

November 01, 2024

How Spring @Transactional Works Under the Hood

September 14, 2024

Gradle Build Performance Tuning: From 5 Minutes Down to 2

August 10, 2024

Managing Dependencies in One Place with Gradle Version Catalog

What Is a Java Record and When Should You Use It?

Four Decisions to Make Before Adding a Cache Layer to Redis

Why Redis Is Fast and How to Use Each Data Structure

The Proxy Pattern Hidden Behind @Transactional

Kafka Connect: Monitoring and Incident Response

Kafka Connect: Building a Debezium CDC Pipeline

Kafka Connect: Introduction and Architecture

Tree of Thoughts and RAG in Prompt Engineering

February 10, 2024

Prompt Engineering Techniques

February 03, 2024

Prompt Engineering Basics and LLM Settings

January 27, 2024

Differences Between HTTP/1.1 and HTTP/2

January 03, 2024

2023 (23)

Spring RestClient Usage and Differences from RestTemplate

November 23, 2023

Optimizing Java Images with Dockerfile Best Practices

October 01, 2023

Java 21 LTS Is Here: What Changed?

September 20, 2023

Decorator Pattern: Combining Features Without Inheritance

August 12, 2023

Why Does a Kafka Consumer Keep Falling Behind?

Kafka Message Keys: Is It Really Enough to Just Put One In?

Kafka Exactly-Once: Is It Really Processed Only Once?

Kafka Producer: How Safe and How Fast?

Kafka Streams Error Handling and Recovery Strategies

Docker Compose Operational Patterns and Environment-Specific Configuration Strategy

Building a Local Environment with the Docker Compose Specification

Kafka Streams Windows and Joins

What Is Docker Compose?

Kafka Streams KStream and KTable

Kafka Streams Concepts and Architecture

Kafka Consumer Offsets and Commit Strategies

Kafka Error Handling and Dead Letter Topic Design

What Is Kafka Schema Registry and Why Does It Matter?

Why Kafka Consumer Rebalancing Happens

How Many Kafka Partitions Do You Need? Why More Consumers Do Not Always Increase Throughput

Kafka Topic Configuration Reference

Java Sealed Class vs Abstract Class vs Interface: When to Use Each

February 07, 2023

Kafka Consumer Reprocessing Strategies

January 05, 2023

2022 (17)

ChatGPT: Can AI Replace Developers?

December 12, 2022

Fixing gem Permission Errors (Gem::FilePermissionError)

November 30, 2022

Adapter Pattern: The Solution for Incompatible Interfaces

October 15, 2022

Auto-Create Spring Batch Metadata Tables

September 01, 2022

How to Generate Random Numbers in Java and What to Watch

August 15, 2022

Turn Off the Charging Chime on MacBook

Set Default Values in Spring @Value Annotation

How to Read MySQL EXPLAIN Query Plans

What Is Spring Cloud OpenFeign and What Should You Watch Out For

FileNotFoundException When Running as a JAR

Why MySQL Joins and ORDER BY Get Slow

Fix xcrun: invalid active developer path After a macOS Upgrade

Why Is My MySQL Query Slow Even With an Index?

Where to Start When Analyzing MySQL Slow Queries

Fixing JUnit5 @DisplayName Not Working in IntelliJ

Profiling Applications in IntelliJ

February 04, 2022

Simplify Object Mapping with MapStruct

January 03, 2022

2021 (18)

Java ThreadLocal: Usage and Caveats

November 06, 2021

What Is New in Java 17: First LTS Release in 3 Years

October 02, 2021

git push Error: Please use a personal access token instead

August 13, 2021

What If a Spring Data JPA Field Name Matches a Database Reserved Word?

Managing SQL When Using Spring JDBC

Template Method Pattern: Fixing the Skeleton, Changing the Steps

Java effectively final

Java BigDecimal: Accurate Real Numbers and Floating Point

February 17, 2021

Java Optional: 5. A Closer Look at Optional

February 08, 2021

Java Optional: 4. Terminal Optional Methods

February 05, 2021

Java Optional: 3. Intermediate Optional Methods

February 05, 2021

Java Optional: 2. Introduction to Optional

February 02, 2021

Java Optional: 1. What Is null?

January 28, 2021

Java BigInteger: Representing Very Large Integers

January 17, 2021

Spring Cloud Config: Changes in Spring Boot 2.4

January 11, 2021

Querydsl: Avoid JPA N+1 with fetch join

January 07, 2021

What Are Coupling and Cohesion?

January 04, 2021

Querydsl: Introduction and Usage

January 01, 2021

2020 (34)

How to Avoid Storing _class Field in MongoDB from Spring Boot

December 27, 2020

Encryption and Decryption in Java

December 02, 2020

MyBatis Error: Invalid bound statement (not found)

November 16, 2020

Can Spring Register and Use Multiple DataSources?

November 03, 2020

Code With Me: Pair Programming with IntelliJ IDEA

October 28, 2020

RestTemplate and WebClient

October 21, 2020

Cryptographic Techniques: Substitution, Transposition, Block Ciphers, and Stream Ciphers

October 14, 2020

How to Use the chmod Command on Linux

October 05, 2020

How to Measure Code Execution Time in Java

September 19, 2020

September 02, 2020

Design Your GitHub Profile

August 11, 2020

How to Fix a Node.js Project Not Being Recognized in IntelliJ

August 02, 2020

How to Get the auto_increment Key Value After Insert in MyBatis

How to Run Code When a Spring Boot Application Starts

What’s New in Java 14?

Builder Pattern for Many Parameters

Resolving DataBufferLimitException in Spring WebClient

Java Scripting API: Migrating to GraalVM

What Is the crossdomain.xml File?

Java Scripting API: Bindings, ScriptContext, and Execution Performance

Java Scripting API: Calling JavaScript Functions from Java

JSON Schema: Implementing a Validator in Java

JSON Schema: Combining Schemas, Conditional Schemas, and Reuse

What Is RSS? RSS 2.0 Specification and Format

JSON Schema: Basic Schema Definitions and Validation

February 27, 2020

JSON Schema: What Is JSON Schema?

February 19, 2020

Spring Cloud Config: Auto Refresh with Git Webhook

February 12, 2020

Comparing Performance: String vs StringBuilder vs StringBuffer in Java

February 04, 2020

Spring Cloud Config: Spring Cloud Bus Example

February 01, 2020

Spring Cloud Config: Introduction and Example

January 31, 2020

Add Comments to a Jekyll Blog with utterances

January 27, 2020

Can Spring Include Package Names in Bean Identifiers?

January 22, 2020

Why Constructor Injection Is Preferred Over Field Injection with @Autowired

January 19, 2020

How to Fix ClassNotFoundException: JAXBException When Running a Spring Boot Project on Java 9

January 13, 2020

2019 (70)

Stack Overflow, Growth and Experience Points for Developers

December 15, 2019

[Effective Java 3rd Edition] Item 11. Always Override hashCode When You Override equals

December 01, 2019

[Effective Java 3rd Edition] Item 76. Strive for Failure Atomicity

November 16, 2019

[Effective Java 3rd Edition] Item 23. Prefer Class Hierarchies to Tagged Classes

November 12, 2019

[Effective Java 3rd Edition] Item 24. Favor Static Member Classes over Nonstatic

November 10, 2019

[Effective Java 3rd Edition] Item 15. Minimize the Accessibility of Classes and Members

November 06, 2019

[Effective Java 3rd Edition] Item 86. Implement Serializable with Great Caution

November 02, 2019

[Effective Java 3rd Edition] Item 89. For Instance Control, Prefer Enum Types to readResolve

October 30, 2019

[Effective Java 3rd Edition] Item 90. Consider Serialization Proxies Instead of Serialized Instances

October 26, 2019

[Effective Java 3rd Edition] Item 88. Write readObject Methods Defensively

October 20, 2019

[Effective Java 3rd Edition] Item 87. Consider Using a Custom Serialized Form

October 16, 2019

[Effective Java 3rd Edition] Item 85. Prefer Alternatives to Java Serialization

October 12, 2019

[Effective Java 3rd Edition] Chapter 12. Serialization

October 11, 2019

[Effective Java 3rd Edition] Item 81. Prefer Concurrency Utilities to wait and notify

October 07, 2019

[Effective Java 3rd Edition] Item 80. Prefer Executors, Tasks, and Streams to Threads

October 03, 2019

[Effective Java 3rd Edition] Item 79. Avoid Excessive Synchronization

September 29, 2019

[Effective Java 3rd Edition] Chapter 11. Concurrency

September 27, 2019

[Effective Java 3rd Edition] Item 78. Synchronize Access to Shared Mutable Data

September 15, 2019

[Effective Java 3rd Edition] Chapter 10. Exceptions

September 03, 2019

[Effective Java 3rd Edition] Item 68. Adhere to Generally Accepted Naming Conventions

August 24, 2019

[Effective Java 3rd Edition] Item 62. Avoid Strings Where Other Types Are More Appropriate

August 21, 2019

Factory Method Pattern: Delegating Object Creation to Subclasses

August 17, 2019

[Effective Java 3rd Edition] Chapter 9. General Programming

August 14, 2019

What Is the Difference Between #{} and ${} in MyBatis?

August 10, 2019

[Effective Java 3rd Edition] Chapter 8. Methods

August 03, 2019

Java Serialization: readResolve and writeReplace

[Effective Java 3rd Edition] Item 44. Favor the Use of Standard Functional Interfaces

Java Serialization: writeObject and readObject

[Effective Java 3rd Edition] Chapter 7. Lambdas and Streams

[Effective Java 3rd Edition] Item 39. Prefer Annotations to Naming Patterns

[Effective Java 3rd Edition] Chapter 6. Enums and Annotations

[Effective Java 3rd Edition] Chapter 5. Generics

[Effective Java 3rd Edition] Chapter 4. Classes and Interfaces

Sorting a MySQL VARCHAR Column as a Number

Handling JSONP in Spring Boot and Solving CORS Issues

[Effective Java 3rd Edition] Chapter 3. Methods Common to All Objects

The Difference Between map and flatMap in Java

Squash Commits with git rebase

Java Serialization: What to Consider and Why It Is Discouraged

Building an IntelliJ Plugin: 3. Build & Publish

Building an IntelliJ Plugin: 2. Define an Action

Building an IntelliJ Plugin: 1. Environment Setup

Why Do We Need Vuex?

Manage Multiple Java Versions with jEnv

Fixing IntelliJ Error: source release 8 requires target release 1.8

Detect JAXB Parsing Errors with ValidationEventHandler

JAXB Marshalling and Unmarshalling

FTP Active vs Passive Mode

Java Exceptions: Checked vs Unchecked

Java Licensing? OpenJDK vs Oracle JDK

February 24, 2019

[Effective Java 3rd Edition] Chapter 2. Creating and Destroying Objects

February 19, 2019

Java Streams: 5. Common Mistakes

February 11, 2019

Java Streams: 4. Examples

February 09, 2019

Setting Up a Spring MVC + Maven Project in IntelliJ

February 08, 2019

Java Streams: 3. Terminal Operations

February 06, 2019

Java Streams: 2. Intermediate Operations

February 05, 2019

Java Streams: 1. API Overview and Stream Creation

February 04, 2019

[Effective Java 3rd Edition] Item 17. Minimize Mutability

February 02, 2019

The final Keyword in Java

January 28, 2019

[Effective Java 3rd Edition] Item 82. Document Thread Safety

January 28, 2019

[Effective Java 3rd Edition] Item 74. Document All Exceptions Thrown by Each Method

January 25, 2019

Numeric Literals and Underscores in Java

January 23, 2019

[Effective Java 3rd Edition] Item 66. Use Native Methods Judiciously

January 21, 2019

How to Autowire a Static Field

January 19, 2019

[Effective Java 3rd Edition] Item 58. Prefer for-each Loops to Traditional for Loops

January 15, 2019

[Effective Java 3rd Edition] Item 8. Avoid Finalizers and Cleaners

January 11, 2019

Multiple Tomcat Instances

January 10, 2019

[Effective Java 3rd Edition] Item 31. Use Bounded Wildcards to Increase API Flexibility

January 07, 2019

[Effective Java 3rd Edition] Item 50. Make Defensive Copies When Needed

January 04, 2019

Installing Node.js on macOS and Running an Example

January 02, 2019

2018 (97)

Getting Started with Node.js

December 30, 2018

Java Serialization: What Is SerialVersionUID?

December 28, 2018

Java Serialization: What Is Serialization?

December 26, 2018

[Effective Java 3rd Edition] Item 42. Prefer Lambdas to Anonymous Classes

December 19, 2018

Benefits of Java Generics and Pitfalls to Avoid

December 19, 2018

[Effective Java 3rd Edition] Item 4. Enforce Noninstantiability with a Private Constructor

December 15, 2018

December 13, 2018

Java 8 Date and Time

December 11, 2018

Why Java Date and Calendar Are a Bad Fit

December 09, 2018

[Effective Java 3rd Edition] Item 28. Prefer Lists to Arrays

December 07, 2018

Differences Between var, let, and const

December 05, 2018

[Effective Java 3rd Edition] Item 34. Use Enums Instead of Int Constants

December 02, 2018

Server-Side Rendering vs Client-Side Rendering

November 26, 2018

Python switch Statements

November 18, 2018

[Effective Java 3rd Edition] Item 18. Favor Composition over Inheritance

November 15, 2018

[Effective Java 3rd Edition] Item 26. Don't Use Raw Types

November 14, 2018

[Effective Java 3rd Edition] Item 10. Obey the general contract when overriding equals

November 10, 2018

Python URL Parsing and Calling (urllib)

November 09, 2018

Entering Korean Comments in Python (SyntaxError: Non-ASCII character)

November 04, 2018

[Effective Java 3rd Edition] Item 2. Consider a builder when faced with many constructor parameters

November 02, 2018

Python if __name__ == "__main__" Meaning

October 28, 2018

Argument and Parameter

October 23, 2018

Docker: Following Docker Installation and Commands

September 28, 2018

log4j, logback, and log4j2

September 21, 2018

Java Kafka Producer and Consumer configs Settings

September 13, 2018

Java Kafka Producer and Consumer Example Implementation

September 10, 2018

Installing Jekyll on Windows 10 and Creating GitHub Blog

September 04, 2018

Cron Expressions

August 26, 2018

Gradle Project Structure and Gradle Wrapper

August 19, 2018

What is Gradle?

August 12, 2018

Java Upcasting and Downcasting

August 04, 2018

Setting Up Log4j2 in Spring Boot

Setting Up Spring Boot Project in IntelliJ

grep Examples and Options

Java and Behavior Parameterization

Change Git Commit Author (Changing Commit Author)

Difference Between Process and Thread

Naver Interview Review (SW Development, Phone Interview, Technical Interview)

NHN Technology Services Written Test Review (SW Development, NTS pretest)

Software Maestro Interview Review (Group Discussion Evaluation, Coding Test)

Spring Bean Lifecycle Methods and Execution Order

Com2us Interview Review (Platform Development)

Korea Electric Power Corporation Interview Review (IT Information & Communication)

Java Method Overriding and Overloading

LINE Plus Interview Review (SW Development, Technical Interview)

LeetCode 344. Reverse String

Lotte Data Communication Company Spectacle Audition Review

Java String Objects and String Literals

Binary Search Tree: Implementation in Java

Binary Search Tree: Theory and Introduction

Observer Pattern

Java Collection Synchronization

LeetCode 2. Add Two Numbers

LeetCode 3. Longest Substring Without Repeating Characters

Java References and Garbage Collection

Spring Framework Summary: Testing

Java Garbage Collection

Functional Programming and Object-Oriented Programming

Spring Framework Summary: Inversion of Control

Why Are Computers Based on Binary System?

Spring Framework Summary: Design Patterns

Java String replaceAll Method $(Dollar Sign) Issue

Strategy Pattern

Finding Prime Numbers Quickly Using Sieve of Eratosthenes

Singleton Pattern

Java Reflection and Dynamic Loading

February 25, 2018

Resolving Jekyll Execution Error on MacOS High Sierra

February 21, 2018

Resolving MySQL Root Password Change Error on Mac OS

February 19, 2018

Levenshtein Distance Algorithm (Edit Distance Algorithm)

February 19, 2018

February 17, 2018

Time Complexity and Space Complexity

February 12, 2018

The this Keyword in Java

February 08, 2018

TCP vs UDP Differences and TCP/IP

February 04, 2018

Java File Compression and Decompression (ZipInputStream, ZipOutputStream)

February 03, 2018

Creating Java Executable Files

February 01, 2018

Abstract Classes and Methods in Java

January 29, 2018

Java Access Modifiers

January 24, 2018

Java Inheritance

January 23, 2018

Why Does Java Main Method Use public static?

January 20, 2018

NTFS, FAT32, and exFAT Formats

January 17, 2018

LeetCode 412. Fizz Buzz

January 17, 2018

LeetCode 292. Nim Game

January 16, 2018

Big Endian and Little Endian

January 15, 2018

scp and rsync (Secure Copy & Remote Synchronization)

January 12, 2018

LeetCode 1. Two Sum

January 09, 2018

Resolving Maven Tomcat 404 Error

January 08, 2018

January 07, 2018

January 06, 2018

January 06, 2018

Connecting Apache and Tomcat (apache, tomcat, mod_jk)

January 05, 2018

jQuery Sortable (Implementing Sorting with Drag and Drop)

January 04, 2018

Java Finalize Method

January 03, 2018

Java Swing LookAndFeel

January 02, 2018

Java Data Types

January 01, 2018

Java Language Characteristics

January 01, 2018

Bracket Matching with a Stack (Java)

January 01, 2018

Migrated to GitHub Blog

January 1, 2018

Started Blog

June 18, 2014