System.Collections.IList Interface

Summary

Represents a collection of objects that can be individually accessed by index.

C# Syntax:

public interface IList : ICollection, IEnumerable

IList is a descendant of the ICollection interface and is the base interface of all lists. IList implementations fall into three categories: read-only, fixed-size, variable-size. A read-only IList cannot be modified. A fixed-size IList does not allow the addition or removal of elements, but it allows the modification of existing elements. A variable-size IList allows the addition, removal and modification of elements.

System.Collections Namespace | ICollection

System.Collections.IList Member List:

Public Properties

IsFixedSize	Read-only When implemented by a class, gets a value indicating whether the IList has a fixed size.
IsReadOnly	Read-only When implemented by a class, gets a value indicating whether the IList is read-only.
Item	Read-write When implemented by a class, gets or sets the element at the specified index.

Public Methods

Add	When implemented by a class, adds an item to the IList.
Clear	When implemented by a class, removes all items from the IList.
Contains	When implemented by a class, determines whether the IList contains a specific value.
IndexOf	When implemented by a class, determines the index of a specific item in the IList.
Insert	When implemented by a class, inserts an item to the IList at the specified position.
Remove	When implemented by a class, removes the first occurrence of a specific object from the IList.
RemoveAt	When implemented by a class, removes the IList item at the specified index.

Hierarchy:

• System.Collections.ICollection
• System.Collections.IEnumerable
• System.Collections.IList

System.Collections.IList Member Details

Summary

When implemented by a class, gets a value indicating whether the IList has a fixed size.

C# Syntax:

bool IsFixedSize {get;}

A collection with a fixed size does not allow the addition or removal of elements after the collection is created, but it allows the modification of existing elements.

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Summary

When implemented by a class, gets a value indicating whether the IList is read-only.

C# Syntax:

bool IsReadOnly {get;}

A collection that is read-only does not allow the addition, removal, or modification of elements after the collection is created.

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Summary

When implemented by a class, gets or sets the element at the specified index.

C# Syntax:

object this[int index] {get; set;}

index

The zero-based index of the element to get or set.

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	index is not a valid index in the IList.
NotSupportedException	The property is set and the IList is read-only.

This property provides the ability to access a specific element in the collection by using the following syntax: myCollection[index] .

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Summary

When implemented by a class, adds an item to the IList.

C# Syntax:

int Add(    object value );

value

The Object to add to the IList.

Return Value:

The position into which the new element was inserted.

Exceptions

Exception Type	Condition
NotSupportedException	The IList is read-only. -or- The IList has a fixed size.

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Summary

When implemented by a class, removes all items from the IList.

C# Syntax:

void Clear();

Exceptions

Exception Type	Condition
NotSupportedException	The IList is read-only.

Implementations of this method can vary in how they handle the ICollection.Count and the capacity of a collection. Typically, the count is set to zero. The capacity can be set to zero or a default value, or it can remain unchanged.

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Summary

When implemented by a class, determines whether the IList contains a specific value.

C# Syntax:

bool Contains(    object value );

value

The Object to locate in the IList.

Return Value:

true if the Object is found in the IList; otherwise, false.

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Summary

When implemented by a class, determines the index of a specific item in the IList.

C# Syntax:

int IndexOf(    object value );

value

The Object to locate in the IList.

Return Value:

The index of value if found in the list; otherwise, -1.

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Summary

When implemented by a class, inserts an item to the IList at the specified position.

C# Syntax:

void Insert(    int index,    object value );

index

The zero-based index at which value should be inserted.

value

The Object to insert into the IList.

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	index is not a valid index in the IList.
NotSupportedException	The IList is read-only. -or- The IList has a fixed size.

If index equals the number of items in the IList, then value is appended to the end.

In collections of contiguous elements, such as lists, the elements that follow the insertion point move down to accomodate the new element. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hashtable.

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Summary

When implemented by a class, removes the first occurrence of a specific object from the IList.

C# Syntax:

void Remove(    object value );

value

The Object to remove from the IList.

Exceptions

Exception Type	Condition
NotSupportedException	The IList is read-only. -or- The IList has a fixed size.

In collections of contiguous elements, such as lists, the elements that follow the removed element move up to occupy the vacated spot. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hashtable.

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Summary

When implemented by a class, removes the IList item at the specified index.

C# Syntax:

void RemoveAt(    int index );

index

The zero-based index of the item to remove.

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	index is not a valid index in the IList.
NotSupportedException	The IList is read-only. -or- The IList has a fixed size.

In collections of contiguous elements, such as lists, the elements that follow the removed element move up to occupy the vacated spot. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hashtable.

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