Using C # Indexer

Indexer is a new addition in C #, some friends may be confused, some of the things that have been done recently
Often use index, conveniently write a simple example for everyone to see if there are any questions to ask!

This example contains three classes: DataRow, DataItem, Dataitemcollection.
The indexer is used in dataitemcollection.

Using System;
Using System.Collections;
public static void Main (string [] args)
{
DataRow MyDataRow = new DataRow ();
DataItem Mydataitem = new DataItem ("Text", "Value");
DATAROW.DATAITEMS.ADD (Mydataitem);
Console.WriteLine (Mydatarow.dataitems[0]. Text);
}
public class DataRow
{
Public Dataitemcollection Dataitems;
Public DataRow ()
{
Dataitems = new Dataitemcollection ();
}
}

public class DataItem
{
private string _text;
private string _value;

Public DataItem (string text, String value)
{
_text=text;
_value=value;
}

public string Text
{
Get
{
return (_text);
}
Set
{
_text=value;
}
}

public string Value
{
Get
{
return (_value);
}
Set
{
_value=value;
}
}

}

public class Dataitemcollection
{
Private ArrayList _array = new ArrayList ();

public virtual int Count
{
Get
{
Return (_array. Count);
}
}

Public DataItem This[int Index]//where indexer is used
{
Get
{
if (index>=0 && Index<_array. Count)
{
Return ((DataItem) _array[index]);
}
Else
{
throw new Exception ("index Overflow");
}
}

Set
{
if (index>=0 && Index<_array. Count)
{
_array[index]=value;
}
Else
{
throw new Exception ("index Overflow");
}
}
}

public void Add (DataItem item)
{
_array. ADD (item);
}


public void Remove (DataItem item)
{
_array. Remove (item);
}

public void Removat (int i)
{
_array. RemoveAt (i);
}
}