How to use Interface

Interface

In OO world , interface is a very important role whichis responsible for connected classes or architect layers .in another word ,it’s the classes or the architecture’s bridge .

With Interface , Classes can“talk”

How does class talk ?

Without interface , as we know ,if class1 want to callclass2 method or use class2 something , it will new a instance of class2 like :

var c2 = new class2();

what’s wrong , class1 know class2 too much .in anotherword , class1 should tell class2 what he need ,but not ask class2 to dosomething for him .

so need interface .

Class1 “tell” what he want to class2 , then class2 doit .

Then How does class1 get what he need ?

Dependency injection . How?

1.Constructor

2.Method

3.Setter

Usually , We use constructor :

As We can see, interface perfectly be the bridge between two classes who need to “talk”

AnotherInterface usage is to connect two architect layers .

A sampleASP.NET project structure .

Conclusion :

when you need to call some method , do not new the class , but list what you want (we call itinterface ), then let other class implement it.Then by dependency injection get the interface do whatever you need .