Javalin is a lightweight web framework for Java and Kotlin, built on top of the Jetty HTTP server. It provides a fluent, consumer-based configuration API for defining HTTP routes, WebSocket endpoints, Server-Sent Events (SSE), static file serving, and more. The framework emphasizes simplicity and developer experience by avoiding annotations and reflection, instead using lambda handlers and a plugin system for extensibility. Core features include request/response handling with before/after lifecycle hooks, path parameter parsing, validation, JSON serialization (Jackson 2/3, Gson), compression (gzip, brotli, zstd), CORS, rate limiting, and SSL/TLS support. The architecture is modular, with separate packages for routing, configuration, plugins, and utilities, and optional satellite modules for metrics (Micrometer), template rendering (multiple engines), and testing tools. Javalin is designed as a library to be embedded in applications, not as a standalone server, and is distributed via Maven Central.
This repository is a curated collection of Java interview questions and answers, organized by topics such as Core Java, Collections, Concurrency, Spring, Hibernate, SQL, and more. It also includes several small, self-contained Java projects that demonstrate specific concepts: a custom Stream API implementation (custom-stream), a deadlock example (deadlock), a set of LeetCode algorithm solutions (leetcode-221-maximal-square), and a flawed code review snippet (review). The primary value is the extensive markdown documentation with links to external resources, making it a useful study aid for Java interview preparation. The code examples are educational but not production-grade; the custom-stream project is the most notable for illustrating the internal pipeline pattern of Java Streams. The repository is static and has not been actively updated in some time, though the content remains relevant for many core Java topics.