Java 9 Dependency Injection

Circular dependency in the Spring framework

Let's explore how circular dependency occurs in the Spring framework and how to deal with it. Spring provides an IoC container that loads all the beans and tries to create objects in a specific order so that they work properly. For example, say we have three beans with the following dependency hierarchy:

• Employee bean
• HRService bean
• CommonUtilService bean

The Employee bean depends on the HRService bean, which depends on the CommonUtilService bean.

In this case, CommonUtilService is considered a low-level bean, while the Employee bean is considered a high-level bean. Spring will first create an object for all low-level beans so that it creates the CommonUtilService bean, then it will create the ...