About interface repeat inheritance question in c#?

Question

Hello friend,

     

 My Codes:

 

public interface IEnumerable2{

// Some members ...

void MethodOfIEnumerable2();

}

public interface ICollection2 : IEnumerable2{

// Some members ...

void MethodOfICollection2();

}

public interface IList2 : ICollection2, IEnumerable2{

// Some members ...

void MethodOfIIList2();

}

/// <summary>

/// Implement class.

/// </summary>

public class ArrayList2:IList2,ICollection2,IEnumerable2{

 

     // Some members ...

 

public void MethodOfIEnumerable2(){

Console.WriteLine("IEnumerable2 In ArrayList2");

}

public void MethodOfICollection2(){

Console.WriteLine("ICollection2 In ArrayList2");

}

public void MethodOfIIList2() {

Console.WriteLine("IList2 In ArrayList2");

}

}

/// <summary>

/// Implement class.

/// </summary>

public class ArrayList3 : IList2{   // Also correct.

   

     // Some members ... 

 

public void MethodOfIEnumerable2(){

Console.WriteLine("IEnumerable2 In ArrayList3");

}

public void MethodOfICollection2() {

Console.WriteLine("ICollection2 In ArrayList3");

}

public void MethodOfIIList2(){

Console.WriteLine("IList2 In ArrayList3");

}

}

 

class Program{

static void Main(string[] args) {

ArrayList2 al2 = new ArrayList2();

ArrayList3 al3 = new ArrayList3();

al2.MethodOfIEnumerable2();

al2.MethodOfICollection2();

al2.MethodOfIIList2();

Console.WriteLine();

al3.MethodOfIEnumerable2();

al3.MethodOfICollection2();

al3.MethodOfIIList2();

Console.ReadKey(true);

}

}

 

Now, My question is:

Because ICollection 2 inherited IEnumerable 2, so IList2 indirectly inherited IEnumerable 2, but in a statement IList2, we repeat inherited IEnumerable2. Seem to repeat inherited? The c# compiler team members do so for what purpose?

 

Thank in advance. :)