Abstract Class implements the methods of Interface

DICS Purnea

Any one help me to answer the below issue. We have one interface ICollection and one abstract class CollectionBase that inherit the ICollection. That already define in System.Collections library.

[ComVisible(true)]
public interface ICollection : IEnumerable
{
int Count { get; }
object SyncRoot { get; }
bool IsSynchronized { get; }
void CopyTo(Array array, int index);
}
//Abstract Class
public abstract class CollectionBase : IList, ICollection, IEnumerable
{
protected CollectionBase();
protected CollectionBase(int capacity);
[ComVisible(false)]
public int Capacity { get; set; }
public int Count { get; }
protected ArrayList InnerList { get; }
protected IList List { get; }
public void Clear();
public IEnumerator GetEnumerator();
public void RemoveAt(int index);
protected virtual void OnClear();
protected virtual void OnClearComplete();
protected virtual void OnInsert(int index, object value);
protected virtual void OnInsertComplete(int index, object value);
protected virtual void OnRemove(int index, object value);
protected virtual void OnRemoveComplete(int index, object value);
protected virtual void OnSet(int index, object oldValue, object newValue);
protected virtual void OnSetComplete(int index, object oldValue, object newValue);
protected virtual void OnValidate(object value);
}

As we know that the class which inherits interface that we must have to implements all methods of the interface. How it is possible that CollectionBase class that didn't implements all the methods of ICollection Interface.

5 Replies

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Mageshwaran R6y ago
Hi,
Please refer the below link, it might helps you
https://stackoverflow.com/questions/2705163/c-abstract-classes-need-to-implement-interfaces
0
DICS Purnea7y ago
I do not want to create anything from my side, I just want to understand the first question where ICollection interface is containing CopyTo method and CollectionBase clase inherited ICollection interface and it did not implement the CopyTo method. These are inbuild class and interface. How they did it?
0
Farhan Ahmed7y ago
why do you want to create abstract class? Create non abstract class and impliment interface method and along with create new method if you wish to. I did not get your requirment.
0
DICS Purnea7y ago
Thanks for your reply, but still there is one confusion.

Why I am getting the compilation error for below code

public interface IA

{

void Add(int a, int b);

void Sub(int a, int b);

}

//Abstract class

abstract class AbstractInterface : IA

{

public void Add(int x, int y)

{

Console.WriteLine("Sum = {0}", x + y);

}

}

but we need to mention the 2nd method in abstract class as

public abstract void Sub(int a, int b);

If you go through the ICollection interface there is CopyTo method which is not mention in the abstract class CollectionBase so that the class derived from CollectionBase would be override the CopyTo method
0
Farhan Ahmed7y ago
If a class inherits an interface, what are the 2 options available for that class?

Option 1: Provide Implementation for all the members inherited from the interface.
Option 2: If the class does not wish to provide Implementation for all the members inherited from the interface, then the class has to be marked as abstract.
0