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

CollectionExtensions
Comparer<T>

Provides a base class for implementations of the IComparer<T> generic interface.

Dictionary<TKey,TValue>.KeyCollection

Represents the collection of keys in a Dictionary<TKey,TValue>. This class cannot be inherited.

Dictionary<TKey,TValue>.ValueCollection

Represents the collection of values in a Dictionary<TKey,TValue>. This class cannot be inherited.

Dictionary<TKey,TValue>

Represents a collection of keys and values.

EqualityComparer<T>

Provides a base class for implementations of the IEqualityComparer<T> generic interface.

HashSet<T>

Represents a set of values.

KeyedByTypeCollection<TItem>

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.

KeyValuePair
LinkedList<T>

Represents a doubly linked list.

LinkedListNode<T>

Represents a node in a LinkedList<T>. This class cannot be inherited.

List<T>

Represents a strongly typed list of objects that can be accessed by index. Provides methods to search, sort, and manipulate lists.

Queue<T>

Represents a first-in, first-out collection of objects.

SortedDictionary<TKey,TValue>.KeyCollection

Represents the collection of keys in a SortedDictionary<TKey,TValue>. This class cannot be inherited.

SortedDictionary<TKey,TValue>.ValueCollection

Represents the collection of values in a SortedDictionary<TKey,TValue>. This class cannot be inherited

SortedDictionary<TKey,TValue>

Represents a collection of key/value pairs that are sorted on the key.

SortedList<TKey,TValue>

Represents a collection of key/value pairs that are sorted by key based on the associated IComparer<T> implementation.

SortedSet<T>

Represents a collection of objects that is maintained in sorted order.

Stack<T>

Represents a variable size last-in-first-out (LIFO) collection of instances of the same specified type.

SynchronizedCollection<T>

Provides a thread-safe collection that contains objects of a type specified by the generic parameter as elements.

SynchronizedKeyedCollection<K,T>

Provides a thread-safe collection that contains objects of a type specified by a generic parameter and that are grouped by keys.

SynchronizedReadOnlyCollection<T>

Provides a thread-safe, read-only collection that contains objects of a type specified by the generic parameter as elements.

Structs

Dictionary<TKey,TValue>.Enumerator

Enumerates the elements of a Dictionary<TKey,TValue>.

Dictionary<TKey,TValue>.KeyCollection.Enumerator

Enumerates the elements of a Dictionary<TKey,TValue>.KeyCollection.

Dictionary<TKey,TValue>.ValueCollection.Enumerator

Enumerates the elements of a Dictionary<TKey,TValue>.ValueCollection.

HashSet<T>.Enumerator

Enumerates the elements of a HashSet<T> object.

KeyValuePair<TKey,TValue>

Defines a key/value pair that can be set or retrieved.

LinkedList<T>.Enumerator

Enumerates the elements of a LinkedList<T>.

List<T>.Enumerator

Enumerates the elements of a List<T>.

Queue<T>.Enumerator

Enumerates the elements of a Queue<T>.

SortedDictionary<TKey,TValue>.Enumerator

Enumerates the elements of a SortedDictionary<TKey,TValue>.

SortedDictionary<TKey,TValue>.KeyCollection.Enumerator

Enumerates the elements of a SortedDictionary<TKey,TValue>.KeyCollection.

SortedDictionary<TKey,TValue>.ValueCollection.Enumerator

Enumerates the elements of a SortedDictionary<TKey,TValue>.ValueCollection.

SortedSet<T>.Enumerator

Enumerates the elements of a SortedSet<T> object.

Stack<T>.Enumerator

Enumerates the elements of a Stack<T>.

Interfaces

ICollection<T>

Defines methods to manipulate generic collections.

IComparer<T>

Defines a method that a type implements to compare two objects.

IDictionary<TKey,TValue>

Represents a generic collection of key/value pairs.

IEnumerable<T>

Exposes the enumerator, which supports a simple iteration over a collection of a specified type.

IEnumerator<T>

Supports a simple iteration over a generic collection.

IEqualityComparer<T>

Defines methods to support the comparison of objects for equality.

IList<T>

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

IReadOnlyCollection<T>

Represents a strongly-typed, read-only collection of elements.

IReadOnlyDictionary<TKey,TValue>

Represents a generic read-only collection of key/value pairs.

IReadOnlyList<T>

Represents a read-only collection of elements that can be accessed by index.

ISet<T>

Provides the base interface for the abstraction of sets.

Remarks

Many of the generic collection types are direct analogs of nongeneric types. Dictionary<TKey,TValue> is a generic version of Hashtable; it uses the generic structure KeyValuePair<TKey,TValue> for enumeration instead of DictionaryEntry. List<T> is a generic version of ArrayList. There are generic Queue<T> and Stack<T> classes that correspond to the nongeneric versions. There are generic and nongeneric versions of SortedList<TKey,TValue>. Both versions are hybrids of a dictionary and a list. The SortedDictionary<TKey,TValue> generic class is a pure dictionary and has no nongeneric counterpart. The LinkedList<T> generic class is a true linked list and has no nongeneric counterpart.