Java

This Java programming series goes from first classes to production Spring Boot apps. It has more than seventy posts, so it works as a full course.

Early posts cover the language and collections. Later, JDBC fundamentals and JPA and Hibernate add data access. Finally, testing Spring Boot apps ties it all together.

74 articles

10/05/2025 10 min read

JUnit 5: Writing Your First Tests

Executive Summary: A JUnit 5 test is a method annotated @Test that passes when its assertions hold. I…
27/03/2025 6 min read

Code Optimization in Java: Minimize Latency with Profiling

Java latency playbook: allocation and I/O techniques, pooling, async-profiler and JMH guidance, with before/after discipline.
23/02/2025 11 min read

Profiling and Performance Tuning Basics in Java

Executive Summary: Java performance tuning works best as a loop: reproduce under steady state, set a baseline, profile,…
11/01/2025 13 min read

Garbage Collection in Java: Generations, Collectors, and Tuning

Executive Summary: Java garbage collection reclaims objects no GC root can reach and organizes the heap by age…
21/12/2024 12 min read

JVM Memory Areas and Class Loaders: Heap, Stack, Metaspace, and Execution

Executive Summary: When java Main runs, class loaders load your code, the JVM stores data in distinct memory…
21/11/2024 7 min read

Dependency Injection in Spring Boot

Constructor injection, circular dependencies, and advanced Spring Boot DI scenarios with concrete code patterns.
17/11/2024 12 min read

Practice: Build a Concurrent Downloader in Java

Executive Summary: This practice project builds a concurrent link checker in Java two ways: a fixed thread pool…
26/10/2024 12 min read

Structured Concurrency in Java

Executive Summary: Structured concurrency ties subtasks to the scope that started them, so failures and cancellations do not…
14/09/2024 12 min read

Virtual Threads in Java: The New Concurrency Model

Executive Summary: Virtual threads let blocking Java code scale like async code, because a blocked virtual thread frees…
24/08/2024 13 min read

CompletableFuture and Asynchronous Programming in Java

Executive Summary: CompletableFuture builds async work as a pipeline of stages you can transform, chain, and combine. I…
21/07/2024 13 min read

Concurrent Collections in Java

Executive Summary: HashMap breaks under concurrent use, so Java provides concurrent collections built for it. I explain ConcurrentHashMap…
22/06/2024 13 min read

Synchronization and Locks in Java

Executive Summary: Java offers several locking tools, and each solves a different problem. Here I cover synchronized and…
25/05/2024 12 min read

ExecutorService and Thread Pools in Java

Executive Summary: ExecutorService runs tasks on a managed thread pool instead of raw threads. I cover fixed and…
21/04/2024 13 min read

Threads in Java: Creation, Lifecycle, and Coordination

Executive Summary: A Java thread runs a Runnable once you call start, and it moves through a defined…