System.Collections.Generic Namespace

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System.Collections.Generic Namespace

The System.Collections.Generic namespace contains interfaces and classes that define generic collections, which allow users to create strongly typed collections that provide better type safety and performance than non-generic strongly typed collections.

Classes

	Class	Description
	Comparer	Provides a base class for implementations of the IComparer generic interface.
	Dictionary	Represents a collection of keys and values.
	Dictionary.KeyCollection	Represents the collection of keys in a Dictionary. This class cannot be inherited.
	Dictionary.ValueCollection	Represents the collection of values in a Dictionary. This class cannot be inherited.
	EqualityComparer	Provides a base class for implementations of the IEqualityComparer generic interface.
	KeyedByTypeCollection	Provides a collection whose items are types that serve as keys.
	KeyNotFoundException	The exception that is thrown when the key specified for accessing an element in a collection does not match any key in the collection.
	LinkedList	Represents a doubly linked list.
	LinkedListNode	Represents a node in a LinkedList. This class cannot be inherited.
	List	Represents a strongly typed list of objects that can be accessed by index. Provides methods to search, sort, and manipulate lists.
	Queue	Represents a first-in, first-out collection of objects.
	SortedDictionary	Represents a collection of key/value pairs that are sorted on the key.
	SortedDictionary.KeyCollection	Represents the collection of keys in a SortedDictionary. This class cannot be inherited.
	SortedDictionary.ValueCollection	Represents the collection of values in a SortedDictionary. This class cannot be inherited
	SortedList	Represents a collection of key/value pairs that are sorted by key based on the associated IComparer implementation.
	Stack	Represents a variable size last-in-first-out (LIFO) collection of instances of the same arbitrary type.
	SynchronizedCollection	Provides a thread-safe collection that contains objects of a type specified by the generic parameter as elements.
	SynchronizedKeyedCollection	Provides a thread-safe collection that contains objects of a type specified by a generic parameter and that are grouped by keys.
	SynchronizedReadOnlyCollection

Interfaces

	Interface	Description
	ICollection	Defines methods to manipulate generic collections.
	IComparer	Defines a method that a type implements to compare two objects.
	IDictionary	Represents a generic collection of key/value pairs.
	IEnumerable	Exposes the enumerator, which supports a simple iteration over a collection of a specified type.
	IEnumerator	Supports a simple iteration over a generic collection.
	IEqualityComparer	Defines methods to support the comparison of objects for equality.
	IList	Represents a collection of objects that can be individually accessed by index.

Structures

	Structure	Description
	Dictionary.Enumerator	Enumerates the elements of a Dictionary.
	Dictionary.KeyCollection.Enumerator	Enumerates the elements of a Dictionary.KeyCollection.
	Dictionary.ValueCollection.Enumerator	Enumerates the elements of a Dictionary.ValueCollection.
	KeyValuePair	Defines a key/value pair that can be set or retrieved.
	LinkedList.Enumerator	Enumerates the elements of a LinkedList.
	List.Enumerator	Enumerates the elements of a List.
	Queue.Enumerator	Enumerates the elements of a Queue.
	SortedDictionary.Enumerator	Enumerates the elements of a SortedDictionary.
	SortedDictionary.KeyCollection.Enumerator	Enumerates the elements of a SortedDictionary.KeyCollection.
	SortedDictionary.ValueCollection.Enumerator	Enumerates the elements of a SortedDictionary.ValueCollection.
	Stack.Enumerator	Enumerates the elements of a Stack.

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Some general guidance on the generics collections

ricom ... supoch14 | Edit | Show History

I wrote an article on this topic some time ago and I still think it's pretty good. You can find the full article here; I've included the introduction and resources below for your convenience.

Six Questions about Generics and Performance

Here are some comments from a recent discussion on Generics that I thought were generally useful. The comments have been edited so that they fit better with the general format of a Q&A session. The origin of this discussion was some commentary on the cost associated with creating instances of generic types where the type parameter is a value-type -- that case is interesting because the code for those classes cannot be shared like it can for reference types, so there can be considerable cost associated with their use.

As always many of these questions would require whole tomes to answer fully, so I'm giving an answer that's brief but only approximately correct. For additional information on Generics please see these links:

http://blogs.msdn.com/kcwalina/archive/2004/03/15/89860.aspx
http://www.15seconds.com/issue/031024.htm
http://research.microsoft.com/projects/clrgen/generics.pdf