// Java · Spring · Hibernate · JUnit · Assembly · CS Core
Deep, tested guides for Java & the JVM — and the computer-science fundamentals underneath.
From Spring Boot and Hibernate migration playbooks to JUnit testing, 8086 assembly, and AI in Java, ankurm.com is a reference-grade library of tutorials written from real debugging experience — not rephrased docs.
“Every great developer was once a beginner who didn’t quit.”
Java & the JVM
The core of the site — production-tested guides across the Spring and Hibernate ecosystem.
Java118Language features, collections, concurrency & modern Java.
Spring21Spring Boot, configuration, web & data essentials.
Spring Cloud18Gateway, Eureka, Resilience4j & microservice migrations.
Hibernate / JPA51Mappings, fetching, performance & version migrations.
JUnit67JUnit 5 & 6 testing patterns, basics to advanced.
Jackson10JSON serialization, custom (de)serializers & tuning.
AI, Prompts & Patterns
Modern tooling and timeless design sense applied to Java work.
Assembly, Web & More
The breadth that makes this a one-stop study and reference hub.
8086 Assembly48TASM/MASM programs & the complete instruction set.
Operating Systems14Scheduling, synchronization & OS algorithm programs.
TypeScript11Types, generics & practical front-end typing.
Angular7Components, services & app-building walkthroughs.
Code Snippets196Quick, copy-ready solutions to everyday problems.
All Posts→The full chronological archive of everything published.
Computer-Science Fundamentals
Curated program collections for core CS & engineering courses.
Featured Migration Playbooks
The site’s most in-depth, frequently-referenced upgrade guides.
HibernateHibernate 5 → 6 → 7: the breaking changes and the silent ones
Spring SecuritySpring Security 5 → 6 → 7: SecurityFilterChain & silent authorization changes
SpringRestTemplate → RestClient: method mapping, error handling & the exchange() trap
Spring CloudZuul → Spring Cloud Gateway: routes, filters & blocking-call traps
Latest From the Blog
The 10 most recent posts, updated automatically as new content goes live.
- Undertow to Tomcat 11 Migration Guide: Jakarta EE 11, Servlet 6.1, and What Actually BreaksA beginner-to-advanced guide to migrating off Undertow on Spring Boot 4: why it was dropped (Jakarta EE 11 / Servlet 6.1), the real Maven error and runtime NoSuchMethodError you get if you fight it, Tomcat 11 tuning, and a verified working Jetty 12.1 alternative — all tested on a real Spring Boot 4.1 app.
- Spring Framework 7 API Versioning: The Complete Guide (Beginner to Advanced)A beginner-to-advanced guide to Spring Framework 7’s built-in API versioning: the version attribute, baseline versions, the supported-versions gotcha, RFC-compliant deprecation headers, client-side ApiVersionInserter, and testing — verified against a real running Spring Boot 4.1 app.
- Micrometer to OpenTelemetry: The Spring Boot 4 Observability Guide (Beginner to Advanced)A beginner-to-advanced guide to Micrometer and Spring Boot 4’s new spring-boot-starter-opentelemetry: what actually changed (it isn’t “Micrometer 2”), the Observation API, context propagation gotchas, a runnable cardinality-explosion demo, and a full migration checklist.
- The Foreign Function & Memory API Beyond “Hello, Panama”: Upcalls, errno, and the Coming JNI LockdownBeyond the standard strlen/struct tutorials: real, runnable FFM API examples for upcalls (C calling back into Java), capturing errno with Linker.Option.captureCallState, measured downcall overhead, and a practical guide to JEP 472’s JNI/FFM lockdown — including live jnativescan output. JDK 22-26.
- Surviving the AI Vulnerability Wave: How to Automate Spring Boot Dependency PatchesAI scanners are flooding the Spring ecosystem with patch PRs faster than any team can review. Build an automated remediation pipeline instead: Dependabot or Renovate tuned for Spring Boot parent POMs and BOMs, a Testcontainers regression gate that decides which bumps are safe, and canary deployments for minor framework upgrades.
- double, BigDecimal, or Fixed-Point: Getting Number Precision Right in JavaWhy 0.1 + 0.2 isn’t 0.3, when double is fine, when BigDecimal is mandatory, and when fixed-point long is fastest. A beginner-to-advanced guide to number precision in Java — with runnable code, real output, a benchmark, rounding modes, MathContext, and a decision table.
- Spring Framework 6 to 7 Migration Guide: Breaking Changes, Deprecated APIs, and Upgrade ChecklistA practical Spring Framework 6 to 7 migration guide covering the Jakarta EE 11 baseline, removed and deprecated APIs, AOT and GraalVM changes, BeanRegistrar and proxy lifecycle changes, JSpecify null safety, testing and security implications, an upgrade checklist, and an AI prompt to scan your project.
- Structured Concurrency in Java: From Your First StructuredTaskScope to Production Patterns (JDK 25/26)A beginner-to-advanced guide to structured concurrency in Java (JDK 25/26). Learn StructuredTaskScope, Joiners (allSuccessfulOrThrow, anySuccessfulOrThrow, race), timeouts, custom joiners, failure handling, thread-dump observability, and how it compares to CompletableFuture — with runnable code, real output, and a diagram.
- Interpreter Design Pattern in Java: Building an Expression EvaluatorLearn the Interpreter design pattern in Java by building a working math expression evaluator. Understand abstract syntax trees, terminal vs. non-terminal expressions, and where this pattern appears in SQL engines, regex, and Spring SpEL.
- GoF Design Patterns in Java: The Complete Guide (All 23 Patterns)Complete reference for all 23 Gang of Four design patterns implemented in Java 17. Each pattern has a dedicated post with beginner-to-advanced coverage, full runnable code, UML diagram, and console output. Creational, Structural, and Behavioral patterns with real-world examples and JDK cross-references.