Many times, I use List. But List has a disadvantage that we cant get item like we get in arrays like: arr[i];
For this to overcome we have a class ArrayList.
ArrayList supports all functionalities of list. Other than this it give the feature of retrieving the items in format: arr[i];
But in both I faced a problem that I was unable to get the Item in my type. I had to typecast it firstly then I can work on it. So to make me work directly on the List items; I have to inherit a CollectionBase. This ensures features of the List. Here I am giving the sample how to create the collection of our own type.
using System;
using System.Collections;
public class Vectors : CollectionBase //CollectionBase is used to add List Functions
//like Add,insert,exist etc.
{
int x,y; //x & y co-ordinates.
public Vectors() //Making new vector to point to origin
{
x=0;
y=0;
}
public int XCoord //Setting & Retrieving X-Co-ordinate
{
get
{
return ( x );
}
set
{
x=value;
}
}
public int YCoord //Setting & Retrieving X-Co-ordinate
{
get
{
return ( y );
}
set
{
y=value;
}
}
public Vectors this[ int index ] //This feature make it work as an arraylist
{
get
{
return( (Vectors) List[index] );
}
set
{
List[index] = value;
}
}
public int Add( Vectors value ) //Add Vector to the list
{
return( List.Add( value ) );
}
public int IndexOf( Vectors value ) //Return Index
{
return( List.IndexOf( value ) );
}
public void Insert( int index, Vectors value )
{
List.Insert( index, value );
}
public void Remove( Vectors value )
{
List.Remove( value );
}
public bool Contains( Vectors value )
{
// If value is not of type Int16, this will return false.
return( List.Contains( value ) );
}
protected override void OnInsert( int index, Object value )
{
// Insert additional code to be run only when inserting values.
}
protected override void OnRemove( int index, Object value )
{
// Insert additional code to be run only when removing values.
}
protected override void OnSet( int index, Object oldValue, Object newValue )
{
// Insert additional code to be run only when setting values.
}
protected override void OnValidate( Object value )
{
if ( value.GetType() != Type.GetType("System.Int16") )
throw new ArgumentException( "value must be of type Int16.", "value" );
}
}
The collection made here can be used easily.
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