These are patterns to achieve loose coupling in java programming
DI(Dependency Injection):
Dependency injection is a pattern used to create instances of objects
that other objects rely upon without knowing at compile time
which class will be used to provide that functionality or simply the way of injecting properties to an object is called dependency injection.
We have three types of Dependency injection
- Constructor Injection
- Setter/Getter Injection
- Interface Injection
Spring will support only Constructor Injection and Setter/Getter Injection.
IOC(Inversion Of Control):
Giving control to the container to create and inject instances of objects that your application depend upon, means instead of you are creating an object using the new operator, let the container do that for you.
Inversion of control relies on dependency injection because a mechanism is needed in order to activate the components providing the specific functionality
The two concepts work together in this way to allow for much more flexible, reusable, and encapsulated code to be written. As such, they are important concepts in designing object-oriented solutions.
Example for Dependency injection
Previously we are writing code like this
Public MyClass{
DependentClass dependentObject
/*
At somewhere in our code we need to instantiate
the object with new operator inorder to use it or perform some method.
*/
dependentObject= new DependentClass();
dependentObject.someMethod();
}
With Dependency injection, the dependency injector will take off the instantiation for us
Public MyClass{
/* Dependency injector will instantiate object*/
DependentClass dependentObject
/*
At somewhere in our code we perform some method.
The process of instantiation will be handled by the dependency injector
*/
dependentObject.someMethod();
}
The above process of giving the control to some other (for example the container) for the instantiation and injection can be termed as Inversion of Control
You can read more on dependency injection and IOC in my answer :- You can find advantages and applications of the concepts here.
What is dependency injection?
