In this post, we’ll talk about Interfaces. Interfaces are basically constraints which Implementing class must follow. In one way, it is similar to abstract
class but doesn’t act as base class. C# doesn’t have multiple inheritance. You can inherit from only one class but you can implement as many interfaces as you like. Also, one point to understand is that access modifiers like private
, public
, protected
, etc. are not legal in case of interfaces. Hence, without wasting time, let’s jump into the demos.
Below is the simple interface in its plain form.
namespace InterfaceDemo
{
interface ITransaction
{
void doTransaction();
double getAmount { get; }
}
}
Now, let us go ahead and create one class which implements the same. Below is the default implementation for the same. You may also notice that since I am not having setter in interface, hence in Implementation that came as private setter which means value can be set from constructor.
namespace InterfaceDemo
{
class Transaction :ITransaction
{
public void doTransaction()
{
throw new System.NotImplementedException();
}
public double getAmount { get; private set; }
}
}
Below is the modified code for class implementation.
using System;
namespace InterfaceDemo
{
class Transaction : ITransaction
{
public void startTransaction()
{
Console.WriteLine("Started doing Transaction");
}
public void doTransaction()
{
Console.WriteLine("Doing Cash Transaction");
}
public double getAmount
{
get { return 10000; }
}
}
}
Now, let us go ahead and use the same in main class. While writing the class, you can see available properties and methods to get exposed.
Below is the main class in its finished form.
using System;
namespace InterfaceDemo
{
class Program
{
static void Main(string[] args)
{
Transaction transaction = new Transaction();
transaction.startTransaction();
transaction.doTransaction();
Console.WriteLine(transaction.getAmount);
Console.ReadLine();
}
}
}
Now, when I run the same, it will produce the following output:
However, it is also perfectly legal to have a variable of type Interface
and instantiate a class like shown below. But, while doing so, here I won’t be having method access which is declared and implemented explicitly in class.
using System;
namespace InterfaceDemo
{
class Program
{
static void Main(string[] args)
{
ITransaction transaction = new Transaction();
transaction.doTransaction();
Console.WriteLine(transaction.getAmount);
Console.ReadLine();
}
}
}
With the above change in place, it will print the following output:
Also, we can have main method like shown below:
using System;
namespace InterfaceDemo
{
class Program
{
static void Main(string[] args)
{
var transaction = new Transaction();
transaction.startTransaction();
transaction.doTransaction();
Console.WriteLine(transaction.getAmount);
ITransaction iTransaction = transaction;
Transaction transactionObj = iTransaction as Transaction;
if(transactionObj!=null)
transactionObj.startTransaction();
Console.ReadLine();
}
}
}
Here, I have used cast operator as
to check whether the object is of type class or interface. And, this will produce the following output:
Download link: https://github.com/rahulsahay19/InterfaceDemo
With this, I would like to wrap this session here. Thanks for joining me.
Thanks,
Rahul Sahay
Happy coding!
CodeProject
Hey there, it's Rahul Sahay! I'm thrilled to be a platform specialist at Publicis Sapient, where I get to work on some exciting projects. I've been honing my skills in various aspects of the software development life cycle for more than 15 years, with a primary focus on web stack development. I've been fortunate to have contributed to numerous software development initiatives, ranging from client applications to web services and websites. Additionally, I enjoy crafting application architecture from scratch, and I've spent most of my time writing platform agnostic and cloud agnostic code. As a self-proclaimed code junkie, software development is more than just a job to me; it's a passion! And I consider myself lucky to have worked with an array of cutting-edge technologies, from .NetCore to SpringBoot 3, from Angular to React, and from Azure to AWS and many more cousin technologies...
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