Using a Dependency Injection Container

Using a Dependency Injection Container

Problem 

I have resolved my dependency issue, but how do I instantiate the concrete implementation of interfaces without creating

dependencies somewhere else in the application?

As it stands, I still have to have statements somewhere in the application like

these:

...

IEmailSender sender = new MyEmailSender();

helper = new PasswordResetHelper(sender);

Solution 

The answer is to use a dependency injection container, also known as an IoC container. This is a component that acts as a

broker between the dependencies that a class like PasswordResetHelper declares and the classes that can be used to

resolve those dependencies, such as MyEmailSender.