== Why is this an issue?

`@Autowired` is an annotation in the Spring Framework for automatic dependency injection.
It tells Spring to automatically provide the required dependencies (such as other beans or components) to a class's fields, methods, or constructors, allowing for easier and more flexible management of dependencies in a Spring application.
In other words, it's a way to wire up and inject dependencies into Spring components automatically, reducing the need for manual configuration and enhancing modularity and maintainability.

In any bean class, only one constructor is permitted to declare `@Autowired` with the `required` attribute set to true.
This signifies the constructor to be automatically wired when used as a Spring bean.
Consequently, when the required attribute remains at its default value (true), only a singular constructor can bear the `@Autowired` annotation.
In cases where multiple constructors have this annotation, they must all specify `required=false` to be eligible as candidates for auto-wiring.

== How to fix it

To maintain code clarity and ensure that the Spring context can create beans correctly, have only one constructor annotated with `@Autowired` within a Spring component or set `required = false`.

=== Code examples

==== Noncompliant code example

[source,java,diff-id=1,diff-type=noncompliant]
----
@Component
public class MyComponent {
  private final MyService myService;

  @Autowired
  public MyComponent(MyService myService) {
    this.myService = myService;
    // ...
  }

  @Autowired  // Noncompliant
  public MyComponent(MyService myService, Integer i) {
    this.myService = myService;
    // ...
  }

  @Autowired  // Noncompliant
  public MyComponent(MyService myService, Integer i, String s) {
    this.myService = myService;
    // ...
  }
}
----

==== Compliant solution

[source,java,diff-id=1,diff-type=compliant]
----
@Component
public class MyComponent {
  private final MyService myService;

  @Autowired
  public MyComponent(MyService myService) {
    this.myService = myService;
    // ...
  }

  public MyComponent(MyService myService, Integer i) {
    this.myService = myService;
    // ...
  }

  public MyComponent(MyService myService, Integer i, String s) {
    this.myService = myService;
    // ...
  }
}
----

==== Noncompliant code example

[source,java,diff-id=2,diff-type=noncompliant]
----
@Component
public class MyComponent {
  private final MyService myService;

  @Autowired
  public MyComponent(MyService myService) {
    this.myService = myService;
    // ...
  }

  @Autowired  // Noncompliant
  public MyComponent(MyService myService, Integer i) {
    this.myService = myService;
    // ...
  }

  @Autowired  // Noncompliant
  public MyComponent(MyService myService, Integer i, String s) {
    this.myService = myService;
    // ...
  }
}
----

==== Compliant solution

[source,java,diff-id=2,diff-type=compliant]
----
@Component
public class MyComponent {
  private final MyService myService;

  @Autowired
  public MyComponent(MyService myService) {
    this.myService = myService;
    // ...
  }

  @Autowired(required=false)  // Compliant
  public MyComponent(MyService myService, Integer i) {
    this.myService = myService;
    // ...
  }

  @Autowired(required=false)  // Compliant
  public MyComponent(MyService myService, Integer i, String s) {
    this.myService = myService;
    // ...
  }
}
----

== Resources

=== Documentation

* https://docs.spring.io/spring-framework/reference/core/beans/annotation-config/autowired.html[Spring Framework - Using @Autowired]

=== Articles & blog posts

* https://www.baeldung.com/spring-autowire[Baeldung - Guide to Spring @Autowired]