Use of depenedency injection

[anish jain]

I am new to Spring. What I understand from dependency injection is that it is the way by which an object can be created by container. We don't need to use 'new' operator.

I am not getting the benefits of Depenedency Injection. I read that it hepls us in testing our code.

Can somebody please explain me how it helps in testing with the help of an example

[Atul Kotwale]

Spring's dependency injection help programmer to follow OOPS concept. According to the OOPS concept the classes should be loosely coupled if they has dependency. For example class A has dependency on class B, then one has to create object of class B in class A using new operator. In future if someone changes the constructor of class B then it has to make changes in class A also because the constructor has been used in class A to make object of class B. In this scenario we can say that class A is tightly coupled with class B. Using dependency injection feature we does wiring of the bean using configuration file. So we only need to change configuration file instead of the code. I hope this would clarify you doubt.