The latest articles on DEV Community by Yassin Alm (@yelmach). https://dev.to/yelmach https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3656979%2F15e8664e-139f-4c9a-8d4f-47a22747d858.jpg https://dev.to/yelmach en Yassin Alm Thu, 11 Dec 2025 10:58:51 +0000 https://dev.to/yelmach/spring-boot-ioc-di-what-actually-happens-under-the-hood-1ja9 https://dev.to/yelmach/spring-boot-ioc-di-what-actually-happens-under-the-hood-1ja9 <p>When I started with Spring, annotations like @Autowired felt like magic spells. But relying on "magic" doesn't work in production. To truly master the framework, we have to look under the hood.</p> <p>Here is a breakdown of how the Inversion of Control (IoC) container actually works:</p> <p>🔹 The Container: Many confuse BeanFactory with ApplicationContext.</p> <p>BeanFactory is lazy (instantiates beans only when asked).</p> <p>ApplicationContext (the Spring Boot default) is eager. It creates all Singletons at startup to catch configuration errors early.</p> <p>🔹 Recipe vs. Meal: Spring doesn't just create objects; it creates BeanDefinitions first. Think of the Definition as the recipe and the actual Bean as the meal.</p> <p>🔹 Dependency Injection: Stop using Field Injection (@Autowired on variables).</p> <p>Constructor Injection is the industry standard. It ensures immutability, prevents NullPointerExceptions, and makes Unit Testing possible without loading the whole context.</p> <p>🔹 The Circular Dependency Trick: How does Spring handle Bean A needing Bean B, which needs Bean A? It uses a clever Three-Level Cache system to expose "raw" bean factories before they are fully initialized.</p> <p>Understanding these internals specifically the lifecycle from BeanDefinition to Singleton Cache is often what distinguishes a Junior developer from a Senior Engineer.</p> designpatterns java backend architecture Yassin Alm Thu, 11 Dec 2025 10:54:53 +0000 https://dev.to/yelmach/how-do-you-cache-user-profiles-with-dynamic-follow-buttons-19ih https://dev.to/yelmach/how-do-you-cache-user-profiles-with-dynamic-follow-buttons-19ih <p>The Scenario I’m building Postly, a blogging platform using Spring Boot 3. To make profile loading fast, I want to cache the UserProfile object in Redis.</p> <p>The Issue The profile page has a "Follow/Unfollow" button.</p> <p>If User A views the profile, it says "Follow".</p> <p>If User B (who already follows them) views the same profile, it says "Following".</p> <p>If I cache the whole Profile DTO in Redis, I risk showing the wrong button state to the wrong user.</p> architecture java performance