Dependency injection configurations

In any application, objects collaborate with other objects to perform some useful task. This relationship between one object and another in any application creates a dependency, and such dependencies between objects create tight-coupled programming in the application. Spring provides us with a mechanism to convert tight-coupled programming to loosely-coupled programming. This mechanism is called dependency injection (DI). DI is a concept or design pattern that describes how to create loosely-coupled classes where objects are designed in a manner where they receive instances of the objects from other pieces of code, instead of constructing them internally. This means that objects are given their dependencies at runtime, rather than compile time. So, with DI, we can get a decoupled structure that offers us simplified testing, greater reusability...