Spring Boot Course Structure and Prerequisites
📌 The course is structured in two parts: the first covers fundamental concepts and the second focuses on building web applications and APIs.
📚 Prerequisites include a solid understanding of Java (OOP concepts) and familiarity with relational databases and SQL (tables, primary/foreign keys, basic queries).
🧑‍💻 The instructor, M. Hamadani, has over 20 years of experience and encourages completing all hands-on exercises before viewing the solutions for better retention.

Project Setup and Maven Integration
🛠️ The recommended IDE is IntelliJ IDEA Ultimate Edition due to its built-in Spring Boot generator and smart editor features.
⚙️ The course uses Maven as the build automation tool, which is integrated into IntelliJ, simplifying setup compared to standalone installations.
📂 Project source code is maintained on GitHub, with each commit representing a lesson, and tags provided for starting at specific section points.

Spring Framework vs. Spring Boot
🌟 The Spring Framework is a modular toolbox with layers for dependency injection, web handling, and data access.
🚀 Spring Boot sits atop Spring to simplify development by providing sensible defaults and handling tedious setup, allowing developers to go from idea to application faster.
🧩 Spring ecosystem projects like Spring Data, Security, and Batch extend the framework's capabilities for specific needs.

First Spring Boot Project and Structure
💻 New projects can be generated via `start.spring.io` or directly within IntelliJ IDEA Ultimate.
🧩 The project structure includes the `mvnw` (Maven Wrapper) for consistent builds, `pom.xml` (the heart of the Maven project), and the source folders (`java` for code, `resources` for configuration/assets).
⚙️ Configuration is managed in `application.properties`, which holds key-value pairs like `spring.application.name` and server settings.

Dependency Management with Starters
📦 Starter dependencies (e.g., `spring-boot-starter-web`) provide curated, compatible collections of libraries, simplifying dependency addition.
🔗 Best practice dictates removing the version from project dependencies and letting Spring Boot manage versioning via the `spring-boot-starter-parent` POM file for automatic, compatible updates.
🔄 Dependencies are downloaded locally to the Maven local repository (`.m2/repository`) upon reloading the project in the IDE.

Web Request Handling with Spring MVC and DevTools
🌐 Spring MVC (Model-View-Controller) handles web requests, separating data (Model), presentation (View, e.g., HTML files in `static`), and request handling (Controller).
🖱️ The `@Controller` annotation marks a class, and `@RequestMapping("/")` maps the root URL to a method returning a view name (e.g., "index").
🔁 Spring Boot DevTools enables automatic application restart upon code changes when the "Build project automatically" and "Allow automake to start even if developed application is currently running" compiler settings are enabled in IntelliJ.

Debugging Techniques
🖨️ Simple debugging can be done using `System.out.println` statements to check variable values in the console.
🛑 For advanced debugging, use breakpoints (red dots in the IDE margin) and execute code line-by-line using Step Over (F8) to observe variable states.
➡️ Step Into (F7) allows drilling down into method calls to find the source of errors within implementation logic.

Configuration and Dependency Injection (DI) Basics
🔑 Application settings are configured using key-value pairs in `application.properties` (e.g., `server.port`).
💡 Custom properties (e.g., `app.page-size`) can be injected into fields using the `@Value("${key}")` annotation.
🧩 Dependency Injection (DI) decouples classes by swapping specific implementations (like a payment service) with general interfaces (like `PaymentService`), adhering to the Open/Closed Principle (open for extension, closed for modification).

Implementing Dependency Injection
✍️ DI can be achieved via Constructor Injection (recommended for required dependencies) or Setter Injection (suitable for optional dependencies).
🛠️ When using Constructor Injection, a `@Autowired` annotation is required if there are multiple constructors, instructing Spring which one to use.
🏷️ Spring manages objects, known as Beans, using the IoC (Inversion of Control) Container (`ApplicationContext`).

Managing Beans with Annotations
✅ To tell Spring to manage a class, use stereotyping annotations like `@Component` (general), `@Service` (business logic), or `@Controller` (web handling).
🔄 Spring needs a concrete implementation to satisfy an interface dependency; annotating implementing classes (e.g., `PaypalPaymentService` with `@Service`) resolves the "No qualifying bean" error.
💡 In modern Spring, if a class has a single constructor, the `@Autowired` annotation is optional for injecting dependencies managed by the IoC container.

Key Points & Insights
➡️ Watch lessons sequentially as concepts build upon previous ones; skipping lessons may lead to missing crucial details.
➡️ Complete exercises before viewing solutions to maximize learning retention by struggling with the problems first.
➡️ Use IntelliJ IDEA Ultimate for enhanced productivity via the built-in Spring Boot project generator and smart coding assistance.
➡️ For required dependencies, Constructor Injection is the preferred and safest method to avoid `NullPointerException` errors common with Setter Injection.

📸 Video summarized with SummaryTube.com on Oct 02, 2025, 16:49 UTC