Learn how to add HTTP Basic Auth, JWT Bearer tokens, and role-based access control to Jersey JAX-RS REST APIs. Covers ContainerRequestFilter, SecurityContext, annotations, and Spring Boot integration with annotated Java code.
Build a custom Maven archetype from scratch: create the descriptor, add Velocity-templated source files, install locally, generate a new Spring Boot project from it, and deploy to a team-shared repository. Step-by-step with working code.
Learn how to validate credit card numbers in Java using regular expressions and the Luhn algorithm. Covers Visa, Mastercard, Amex, and Discover patterns, annotated source code, sample output, and JUnit tests.
Master formatting ZonedDateTime in Java with DateTimeFormatter: ISO formatters, custom ofPattern() strings, timezone conversion, parsing, and a full pattern reference table — with annotated code and sample output.
A practical deep dive into Java Message Service (JMS): core concepts, queue vs topic messaging, synchronous and asynchronous consumers, publish-subscribe with Apache ActiveMQ, Spring Boot JmsTemplate, and production best practices.
Understand the difference between Java Comparable and Comparator with side-by-side examples, a decision guide, and modern Java 8 Comparator chaining techniques. Covers naturalOrder, reversed(), thenComparing(), nullsFirst(), and common pitfalls.
Learn how to use Java BufferedReader to read files line by line, read console input, stream lines with Java 8, and choose between BufferedReader, Scanner, and Files.readAllLines(). Includes annotated code examples and a methods reference table.
Master Logback RollingFileAppender with time-based, size-and-time, and fixed-window rolling policies. Includes production-ready logback.xml examples, Spring Boot integration, async logging, and a complete FAQ.
Learn how to mask credit card numbers, SSNs, API keys, and other PII in Logback logs using a custom MaskingConverter, PatternLayout, and logback.xml configuration — with annotated Java code and practical best practices.
A complete implementation of a semantic search engine in pure Java — no external libraries. Covers TF-IDF vectorisation, cosine similarity, and document ranking by meaning. Explains the mathematics behind vector embeddings, how they power RAG and AI search systems, and provides a working query engine with annotated code and sample output. The same architecture used by Pinecone, Weaviate, and Elasticsearch — built from scratch.