Injecting dependencies between POJOs

The term dependency injection is not new-it is used by PicoContainer. Dependency injection is a design pattern that promotes loose coupling between the Spring components--that is, between the different collaborating POJOs. So by applying DI to your complex programming, your code will become simpler, easier to understand, and easier to test.

In your application, many objects are working together for a particular functionality as per your requirement. This collaboration between the objects is actually known as dependency injection. Injecting dependency between the working components helps you to unit test every component in your application without tight coupling.

In a working application, what the end user wants is to see the output. To create the output, a few objects in the application work together and are sometimes coupled. So when you are writing these complex application classes, consider the reusability of these classes and make these classes as independent as possible. This is a best practice of coding that will help you in unit testing these classes independently.