Question

I have a question regarding Interface. There are 2 interface both contain the same Method Test().
Now I’m inheriting both the interface in Sample class.I want to know which Interface’s method will be called?
My code sample is below:

interface IA 
{
    void Test();
}
interface IB
{
    void Test();
}
class Sample: IA, IB
{
    public void Test()
    {
      Console.WriteLine("Which interface will be implemented IA or IB???!");
    }
}
class Program
{
    public static void Main(string[] args)
    {
        Sample t = new Sample();
        t.Test();//Which Interface's Method will called.
        Console.ReadLine();
    }
}

Thanks
Vijendra Singh

Answer 1

The result will be the same for both. If you want different behaviour per interface, you have to explicitly implement them:

interface IA 
{
    void Test();
}
interface IB
{
    void Test();
}
class Sample: IA, IB
{
    void IA.Test()
    {
      Console.WriteLine("Hi from IA");
    }
    void IB.Test()
    {
      Console.WriteLine("Hi from IB");
    }
    public void Test() //default implementation
    {
      Console.WriteLine("Hi from Sample");
    }
}

class Program
{
    public static void Main(string[] args)
    {
        Sample t = new Sample();
        t.Test(); // "Hi from Sample"
        ((IA)t).Test(); // "Hi from IA"
        ((IB)t).Test(); // "Hi from IB"
        Console.ReadLine();
    }
}

If you want default behaviour, create a method with the same signature (thus an implicit interface implementation) and add code for that case. Usually, you just want the explicit implementation though.