ejjung.hashnode.devKey Features of Java Versions (LTS Focus)1. What is LTS (Long-Term Support)? Java LTS (Long-Term Support) refers to specific versions released approximately every three years that receive extended security updates and bug fixes. Unlike non3d ago·5 min read
ejjung.hashnode.devDesign a URL Shortener Like Bit.ly: Notes on the UnknownsThis article is not a step-by-step solution. It’s a record of the assumptions I had, the gaps I discovered, and the details I didn’t fully understand until I tried to design a URL shortener myself. 1. Solved: 2026-01-15 2. Reference Solution https...Jan 17·6 min read
ejjung.hashnode.devAbstract Class vs. Interface0. Introduction Since Java 8 introduced default methods in interfaces, many developers wondered: Do we still need abstract classes? While interfaces have become more powerful, abstract classes continue to play an important role in Java’s type system....Jan 6·3 min read
ejjung.hashnode.devStatic Fields in Inner Classes? Yes, You Can (Since Java 16)1. What Are Nested Classes? A nested class is a class declared within another class. They are categorized into two types based on where they are declared. A nested class declared as a member of another class is called a member class, and a nested cla...Aug 26, 2025·7 min read
ejjung.hashnode.devA Beginner's Guide to Trees1. Introduction to Trees A Tree is a widely used data structure in computer science that simulates a hierarchical tree structure with a set of connected nodes. Unlike linear data structures such as arrays or linked lists, trees allow efficient repres...Aug 22, 2025·3 min read
