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Constructor.md

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Constructor Injection in Bring

In Bring, constructor injection remains a mechanism through which a class's dependencies are provided through its constructor during object initialization.

When Bring creates an instance of a class, it automatically supplies the required dependencies as arguments to the constructor. This ensures that the necessary dependencies are available as soon as the object is instantiated.

In Bring, you typically don't need to use an @Autowired annotation on a single constructor. The framework automatically identifies and utilizes the single available constructor for dependency injection.

Example:

@Component
public class MyClass {
    private final MyDependency dependency;

    public MyClass(MyDependency dependency) {
        this.dependency = dependency;
    }

    // Other class methods...
}

In this example:

  • MyClass features a single constructor that takes MyDependency as a parameter.
  • Bring automatically identifies this constructor for injection without the need for explicit annotations.
  • Upon object creation, Bring detects the available constructor and supplies the necessary MyDependency instance to it.

Constructor injection in Bring simplifies dependency management, especially in scenarios where there's a single constructor, eliminating the need for additional annotations and promoting straightforward dependency wiring. It is particularly useful when defining classes and their dependencies within the Bring framework.

However, in cases where a class contains multiple constructors, @Autowired becomes necessary to guide Bring in selecting the appropriate constructor for injection.

Example with Multiple Constructors:

@Component
public class AnotherClass {
    private final SomeDependency dependency;

    private String someOtherProperty;

    // Constructor 1
    public AnotherClass() {
        // Default constructor
    }

    // Constructor 2
    @Autowired
    public AnotherClass(SomeDependency dependency) {
        this.dependency = dependency;
    }

    // Other class methods...
}

In this case:

  • AnotherClass has multiple constructors.
  • @Autowired annotations are added to the constructors to guide Bring in determining which constructor to use for injection.
  • By specifying @Autowired on the constructors, Bring knows to utilize these constructors for dependency resolution when multiple constructors are available.

Using @Autowired in Bring helps resolve ambiguity when there are multiple constructors, allowing the framework to identify and use the correct constructor for dependency injection.

Note

If you're interested in exploring examples of constructor injection in Bring, you can refer to the test case BringConstructorInjectionTest. This tests case typically demonstrates how Bring instantiates classes and injects dependencies through constructors.