35 Must-Know Dependency Injection Interview Questions and Answers 2025

DI Fundamentals

1.
What is Dependency Injection and why is it used in modern software development?
2.
Explain the concept of Inversion of Control (IoC) and how it relates to Dependency Injection.
3.
What are the main advantages of using Dependency Injection in a software project?
4.
Describe the impact of Dependency Injection on the maintainability of code.
5.
Can you explain the Dependency Inversion Principle and how it differs from Dependency Injection?

Types of Dependency Injection

6.
Compare and contrast constructor injection versus setter injection.
7.
When would you use method injection instead of constructor injection?
8.
Can mixing different types of injection in the same class lead to issues? If so, what kind?
9.
Is there a preferred type of dependency injection when working with immutable objects? Please explain.
10.
How does each type of dependency injection affect the ease of unit testing?

DI Containers and Frameworks

11.
What is a Dependency Injection container and what are its responsibilities?
12.
Can you list some popular Dependency Injection frameworks and their distinctive features?
13.
What is the difference between a Dependency Injection container and a service locator?
14.
How do you configure dependencies within a DI container typically?
15.
Describe a situation where you should opt for a lightweight DI container over a full-fledged framework.

DI in Design Patterns

16.
How does Dependency Injection complement the Factory Design Pattern?
17.
What design pattern may be violated by improper use of Dependency Injection and why?
18.
Can you show how Dependency Injection can be used to implement a Singleton pattern properly?

DI and Unit Testing

19.
How does Dependency Injection improve the testability of a class?
20.
Explain how Dependency Injection facilitates the use of Mock objects in unit tests.
21.
Can you describe a scenario where Dependency Injection made unit testing more challenging?

Best Practices in DI

22.
What is constructor injection overuse, and why should it be avoided?
23.
Describe an anti-pattern in Dependency Injection and how to resolve it.
24.
What could be some potential pitfalls when using automatic wire-up features in DI frameworks?
25.
How should developers manage the lifetime of dependencies provided by DI containers?

Advanced Concepts in DI

26.
Explain the concept of Scoped Dependencies in Dependency Injection.
27.
How does a Dependency Injection framework typically resolve circular dependencies?
28.
What is meant by lazy loading of services in Dependency Injection and when is it useful?

Dependency Injection in Microservices

29.
How does Dependency Injection support the scalability of microservices?
30.
What role does a DI container play in orchestrating microservice dependencies?
31.
How do you manage cross-service dependencies in microservices architecture with DI?

DI in Specific Languages

32.
How is Dependency Injection implemented differently in statically-typed versus dynamically-typed languages?
33.
Explain the concept of property injection in C# and where is it most suitable to use?
34.
How do you perform dependency injection in a JavaScript application without a DI framework?

Real-world Scenarios and Use Cases

35.
Can you describe a real-world problem that you solved using Dependency Injection and how it benefited the project?

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35 Dependency Injection interview questions

What is Dependency Injection and why is it used in modern software development?

Explain the concept of Inversion of Control (IoC) and how it relates to Dependency Injection.

What are the main advantages of using Dependency Injection in a software project?

Describe the impact of Dependency Injection on the maintainability of code.

Can you explain the Dependency Inversion Principle and how it differs from Dependency Injection?

Compare and contrast constructor injection versus setter injection.

When would you use method injection instead of constructor injection?

Can mixing different types of injection in the same class lead to issues? If so, what kind?

Is there a preferred type of dependency injection when working with immutable objects? Please explain.

How does each type of dependency injection affect the ease of unit testing?

What is a Dependency Injection container and what are its responsibilities?

Can you list some popular Dependency Injection frameworks and their distinctive features?

What is the difference between a Dependency Injection container and a service locator?

How do you configure dependencies within a DI container typically?

Describe a situation where you should opt for a lightweight DI container over a full-fledged framework.

How does Dependency Injection complement the Factory Design Pattern?

What design pattern may be violated by improper use of Dependency Injection and why?

Can you show how Dependency Injection can be used to implement a Singleton pattern properly?

How does Dependency Injection improve the testability of a class?

Explain how Dependency Injection facilitates the use of Mock objects in unit tests.

Can you describe a scenario where Dependency Injection made unit testing more challenging?

What is constructor injection overuse, and why should it be avoided?

Describe an anti-pattern in Dependency Injection and how to resolve it.

What could be some potential pitfalls when using automatic wire-up features in DI frameworks?

How should developers manage the lifetime of dependencies provided by DI containers?

Explain the concept of Scoped Dependencies in Dependency Injection.

How does a Dependency Injection framework typically resolve circular dependencies?

What is meant by lazy loading of services in Dependency Injection and when is it useful?

How does Dependency Injection support the scalability of microservices?

What role does a DI container play in orchestrating microservice dependencies?

How do you manage cross-service dependencies in microservices architecture with DI?

How is Dependency Injection implemented differently in statically-typed versus dynamically-typed languages?

Explain the concept of property injection in C# and where is it most suitable to use?

How do you perform dependency injection in a JavaScript application without a DI framework?

Can you describe a real-world problem that you solved using Dependency Injection and how it benefited the project?

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