What are the main differences between dependency injection methods in software systems?

Main methods of dependency injection (Dependency Injection, DI) in Java:

1. Constructor Injection

   • Dependencies are passed through constructor parameters.
   • Ensures immutability of the object after creation.

2. Setter Injection

   • Dependencies are set through setter methods after object creation.
   • Allows changing dependencies during the object's lifecycle.

3. Interface Injection

   • The object implements an interface that allows dependencies to be injected.
   • Used less frequently, requires an additional interface.

4. Field Injection

   • Dependencies are injected directly into class fields (e.g., using @Autowired annotations in Spring).
   • Convenient, but complicates testing and breaks encapsulation.

The choice of method depends on requirements for immutability, testing convenience, and architectural preferences. Constructor injection is considered the safest and most preferred.