Why is this an issue?

Spring @Component, @Controller, @RestController,@Service, and @Repository classes are singletons by default, meaning only one instance of the class is ever instantiated in the application. Typically such a class might have a few static members, such as a logger, but all non-static members should be managed by Spring.

This rule raises an issue when a singleton @Component, @Controller, @RestController, @Service, or @Repository, not annotated with @ConfigurationProperties, has non-static members that are not annotated with one of:

• org.springframework.beans.factory.annotation.Autowired
• org.springframework.beans.factory.annotation.Value
• javax.annotation.Inject
• javax.annotation.Resource
• javax.persistence.PersistenceContext
• jakarta.annotation.Resource
• jakarta.inject.Inject
• jakarta.persistence.PersistenceContext

How to fix it

Add one of these annotations to all non-static members: @Resource, @Inject, @Autowired or @Value.

Code examples

Noncompliant code example

@Controller
public class HelloWorld {

  private String name = null;

  @RequestMapping("/greet", method = GET)
  public String greet(String greetee) {

    if (greetee != null) {
      this.name = greetee;
    }

    return "Hello " + this.name;  // if greetee is null, you see the previous user's data
  }
}