Setter Injection

Setter Injection is a dependency injection technique where dependencies are provided to a class through setter methods rather than constructors. It allows for optional or mutable dependencies, enabling objects to be configured after instantiation. This approach is commonly used in frameworks like Spring to manage object dependencies and promote loose coupling.

Also known as: Setter-based Injection, Setter DI, Property Injection, Method Injection, Setter Method Injection

Why learn Setter Injection?

Developers should use Setter Injection when dependencies are optional or need to be changed at runtime, such as in configuration-heavy applications or when using frameworks that support it. It is particularly useful in scenarios where object creation and dependency wiring are separated, like in Java EE or Spring-based projects, to enhance testability and flexibility.

Learning Resources

• docs: Spring Framework Documentation - Dependency Injection
• tutorial: Baeldung - Setter Injection in Spring
• docs: Martin Fowler - Inversion of Control Containers and the Dependency Injection Pattern
• video: Java Brains - Spring Dependency Injection Tutorial
• book: Head First Design Patterns Book - Dependency Injection Section