Implement two interface with same method in C Sharp

Implement two interface with same method in C# – Learn how to implement two interface with same method in C# and how to call them with a c# code example.

Here is the exact interview question asked : If you implement two interface with same method name in a program then doesn’t method call conflict? In another word, how to call same method from two interfaces in c#? Show them by C# code example.

If we have two interface with same method name then a class need to implement interface explicitly in a program.

We implement the interface explicitly in a class, using interface name e.g. “interfacename.method()”

void ILoanCustomer.GetCostomerInfo()
{

}

Also note that when we use explicit interface implementations, the functions are not public in the class.

In below C# program example, we have two interfaces ILoanCustomer and IBankCustomer. Both have same method name i.e. GetCostomerInfo();

Customer class will implement both interfaces explicitly.

//Interfaces ILoanCustomer & IBankCustomer
//have same method name. That will be implemented
//Explicitely in Customer class
interface ILoanCustomer
{
    void GetCostomerInfo();
}
interface IBankCustomer
{
   void GetCostomerInfo();    
}
 
 
class Customer : ILoanCustomer, IBankCustomer
{
    //Explicit implementation of ILoanCustomer interface
    void ILoanCustomer.GetCostomerInfo()
    {
        Console.WriteLine("Loan Customer ...");
        
    }
    //Explicit IBankCustomer of ILoanCustomer interface
    void IBankCustomer.GetCostomerInfo()
    {
        Console.WriteLine("Bank Customer ...");
       
    }
}
 
//Test
class Program
{
    static void Main(string[] args)
    {
        IBankCustomer bc = new Customer();
        bc.GetCostomerInfo();
 
        ILoanCustomer lc = new Customer();
        lc.GetCostomerInfo();       
       
    }
}
 

Output:

Bank Customer …
Loan Customer …

NOTE:

When a method is explicitly implemented in a class in C#, it cannot be accessed through a class instance, but only through an interface instance. For example

Using interface instance, class method is accessible.

IBankCustomer bc = new Customer();

bc.GetCostomerInfo();

Using class instance can’t access the method e.g.

Customer c = new Customer();

c.GetCostomerInfo();