Spring Boot Dependency Injection u0026 Inversion of Control Essentials Quiz Quiz

Explore key principles of dependency injection and inversion of control in Spring Boot with engaging scenarios and practical concepts. Enhance your understanding of how objects are managed, wired, and maintained, focusing on core terminology and best practices for beginners.

1. Understanding Dependency Injection Basics

   What is the main goal of dependency injection in an application framework like Spring Boot?

   1. To speed up the execution of all Java methods
   2. To completely remove the need for object creation
   3. To increase the number of dependencies in a class automatically
   4. To provide objects with the dependencies they need, rather than objects creating them directly

   Explanation: Dependency injection allows a framework to supply an object's dependencies, making code easier to test and maintain. Increasing the number of dependencies is not a goal. Removing object creation entirely is not feasible since objects must exist. Speeding up execution is not the main focus here.

2. Inversion of Control Concept

   Which statement best defines inversion of control in the context of Spring Boot?

   1. A situation where developers write code without any dependencies
   2. The process where the framework calls application code rather than the code controlling dependencies directly
   3. Enabling the hardware to directly control software services
   4. Allowing users to control all application processes manually

   Explanation: Inversion of control means the framework manages control flow, including dependency management. Writing code with no dependencies is not possible in complex applications. Manual process control contradicts IoC. Hardware controlling software is unrelated to IoC.

3. Identifying Dependency Injection Types

   When a dependency is supplied through a class's constructor method in Spring Boot, what type of dependency injection is this?

   1. Setter injection
   2. Factory injection
   3. Constructor injection
   4. Field injection

   Explanation: Constructor injection passes dependencies by parameters in the constructor. Field injection uses annotations on member variables. Setter injection uses setter methods. Factory injection is not a recognized standard DI type.

4. Field Injection Recognition

   If a private field in a class is annotated to automatically assign its dependency, which type of dependency injection is being used?

   1. Method injection
   2. Aspect injection
   3. Interface injection
   4. Field injection

   Explanation: Field injection assigns dependencies directly to fields using annotations. Interface injection is a different approach requiring specific interfaces. Method injection involves passing dependencies via specific methods, not fields. Aspect injection relates to cross-cutting concerns, not standard DI.

5. Bean Scope Understanding

   In Spring Boot, which scope makes a bean shared and reused across the entire application by default?

   1. Request
   2. Singleton
   3. Session
   4. Prototype

   Explanation: Singleton scope means only one instance of a bean is created and shared across the application. Prototype scope creates a new instance every time it is requested. Request and Session are specific to web contexts and do not apply universally.

6. Annotations and Dependency Injection

   Which annotation is commonly used in Spring Boot to indicate that a class can be injected as a dependency?

   1. @Import
   2. @Component
   3. @Expose
   4. @Implement

   Explanation: @Component marks a class as a candidate for dependency injection. @Implement and @Expose are not standard Spring annotations. @Import is used for configuration, not for marking beans for injection.

7. Automatic Wiring of Dependencies

   Which annotation allows Spring Boot to automatically resolve and inject dependencies into a class?

   1. @Assigned
   2. @Resourceful
   3. @Author
   4. @Autowired

   Explanation: @Autowired tells the framework to inject the required dependency. @Author and @Resourceful are not valid annotations for injection. @Assigned is not a recognized Spring annotation.

8. Benefits of Dependency Injection

   Which is a primary benefit of using dependency injection for managing object dependencies in an application?

   1. Automatic memory management without garbage collection
   2. Improved testability of components by allowing easy substitution of dependencies
   3. Direct hardware interaction from Java code
   4. Faster network speeds in applications

   Explanation: Dependency injection enhances testability by enabling mock or alternative implementations. It does not impact network speed or replace memory management systems. Hardware interaction is unrelated to DI.

9. Circular Dependencies in Dependency Injection

   What issue can occur if two beans depend on each other directly in Spring Boot dependency injection?

   1. Creation of duplicate bean instances
   2. Improved application performance
   3. Beans getting automatically destroyed
   4. A circular dependency, potentially causing initialization errors

   Explanation: Circular dependencies can cause the application context to fail during startup due to an inability to resolve dependencies. Such a situation does not improve performance, nor does it cause automatic destruction or duplication of beans.

10. Loose Coupling Advantage

    How does dependency injection help achieve loose coupling between classes in Spring Boot applications?

    1. By externalizing the creation and binding of dependencies, reducing direct class interconnections
    2. By forcing classes to inherit from each other
    3. By eliminating the use of objects entirely
    4. By embedding logic within every field

    Explanation: Dependency injection decouples classes by managing dependencies externally, making components less reliant on each other. Inheritance and embedding logic increase coupling, and eliminating objects is impractical for application design.