ConcurrentDictionary<TKey,TValue> Constructors

Definition

Namespace:

System.Collections.Concurrent

Assembly:

System.Collections.Concurrent.dll

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class.

Overloads

ConcurrentDictionary<TKey,TValue>()	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the default concurrency level, has the default initial capacity, and uses the default comparer for the key type.
ConcurrentDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>)	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that contains elements copied from the specified IEnumerable<T>, has the default concurrency level, has the default initial capacity, and uses the default comparer for the key type.
ConcurrentDictionary<TKey,TValue>(IEqualityComparer<TKey>)	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the default concurrency level and capacity, and uses the specified IEqualityComparer<T>.
ConcurrentDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>)	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that contains elements copied from the specified IEnumerable has the default concurrency level, has the default initial capacity, and uses the specified IEqualityComparer<T>.
ConcurrentDictionary<TKey,TValue>(Int32, Int32)	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the specified concurrency level and capacity, and uses the default comparer for the key type.
ConcurrentDictionary<TKey,TValue>(Int32, IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>)	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that contains elements copied from the specified IEnumerable, and uses the specified IEqualityComparer<T>.
ConcurrentDictionary<TKey,TValue>(Int32, Int32, IEqualityComparer<TKey>)	Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the specified concurrency level, has the specified initial capacity, and uses the specified IEqualityComparer<T>.

ConcurrentDictionary<TKey,TValue>()

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the default concurrency level, has the default initial capacity, and uses the default comparer for the key type.

public:
 ConcurrentDictionary();

public ConcurrentDictionary ();

Public Sub New ()

Remarks

The default concurrency level is equal to the number of CPUs. The higher the concurrency level is, the more concurrent write operations can take place without interference and blocking. Higher concurrency level values also cause operations that require all locks (for example, table resizing, ToArray and Count) to become more expensive. The default capacity (DEFAULT_CAPACITY), which represents the initial number of buckets, is a trade-off between the size of a very small dictionary and the number of resizes when constructing a large dictionary. Also, the capacity should not be divisible by a small prime number. The default capacity is 31.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary

ConcurrentDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>)

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that contains elements copied from the specified IEnumerable<T>, has the default concurrency level, has the default initial capacity, and uses the default comparer for the key type.

public:
 ConcurrentDictionary(System::Collections::Generic::IEnumerable<System::Collections::Generic::KeyValuePair<TKey, TValue>> ^ collection);

public ConcurrentDictionary (System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey,TValue>> collection);

new System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value> : seq<System.Collections.Generic.KeyValuePair<'Key, 'Value>> -> System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value>

Public Sub New (collection As IEnumerable(Of KeyValuePair(Of TKey, TValue)))

Parameters

collection

IEnumerable<KeyValuePair<TKey,TValue>>

The IEnumerable<T> whose elements are copied to the new ConcurrentDictionary<TKey,TValue>.

Exceptions

ArgumentNullException

collection or any of its keys is null.

ArgumentException

collection contains one or more duplicate keys.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary

ConcurrentDictionary<TKey,TValue>(IEqualityComparer<TKey>)

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the default concurrency level and capacity, and uses the specified IEqualityComparer<T>.

public:
 ConcurrentDictionary(System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public ConcurrentDictionary (System.Collections.Generic.IEqualityComparer<TKey>? comparer);

new System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value> : System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value>

Public Sub New (comparer As IEqualityComparer(Of TKey))

Parameters

comparer

IEqualityComparer<TKey>

The equality comparison implementation to use when comparing keys.

Exceptions

ArgumentNullException

comparer is null.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary

ConcurrentDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>)

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that contains elements copied from the specified IEnumerable has the default concurrency level, has the default initial capacity, and uses the specified IEqualityComparer<T>.

public:
 ConcurrentDictionary(System::Collections::Generic::IEnumerable<System::Collections::Generic::KeyValuePair<TKey, TValue>> ^ collection, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public ConcurrentDictionary (System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey,TValue>> collection, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

new System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value> : seq<System.Collections.Generic.KeyValuePair<'Key, 'Value>> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value>

Public Sub New (collection As IEnumerable(Of KeyValuePair(Of TKey, TValue)), comparer As IEqualityComparer(Of TKey))

Parameters

collection

IEnumerable<KeyValuePair<TKey,TValue>>

The IEnumerable<T> whose elements are copied to the new ConcurrentDictionary<TKey,TValue>.

comparer

IEqualityComparer<TKey>

The IEqualityComparer<T> implementation to use when comparing keys.

Exceptions

ArgumentNullException

collection or comparer is null.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary

ConcurrentDictionary<TKey,TValue>(Int32, Int32)

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the specified concurrency level and capacity, and uses the default comparer for the key type.

public:
 ConcurrentDictionary(int concurrencyLevel, int capacity);

public ConcurrentDictionary (int concurrencyLevel, int capacity);

new System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value> : int * int -> System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value>

Public Sub New (concurrencyLevel As Integer, capacity As Integer)

Parameters

concurrencyLevel

Int32

The estimated number of threads that will update the ConcurrentDictionary<TKey,TValue> concurrently, or in .NET 8+ only, -1 to indicate the default concurrency level.

capacity

Int32

The initial number of elements that the ConcurrentDictionary<TKey,TValue> can contain.

Exceptions

ArgumentOutOfRangeException

concurrencyLevel is less than 1.

-or-

capacity is less than 0.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary

ConcurrentDictionary<TKey,TValue>(Int32, IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>)

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that contains elements copied from the specified IEnumerable, and uses the specified IEqualityComparer<T>.

public:
 ConcurrentDictionary(int concurrencyLevel, System::Collections::Generic::IEnumerable<System::Collections::Generic::KeyValuePair<TKey, TValue>> ^ collection, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public ConcurrentDictionary (int concurrencyLevel, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey,TValue>> collection, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

new System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value> : int * seq<System.Collections.Generic.KeyValuePair<'Key, 'Value>> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value>

Public Sub New (concurrencyLevel As Integer, collection As IEnumerable(Of KeyValuePair(Of TKey, TValue)), comparer As IEqualityComparer(Of TKey))

Parameters

concurrencyLevel

Int32

The estimated number of threads that will update the ConcurrentDictionary<TKey,TValue> concurrently, or in .NET 8+ only, -1 to indicate the default concurrency level.

collection

IEnumerable<KeyValuePair<TKey,TValue>>

The IEnumerable<T> whose elements are copied to the new ConcurrentDictionary<TKey,TValue>.

comparer

IEqualityComparer<TKey>

The IEqualityComparer<T> implementation to use when comparing keys.

Exceptions

ArgumentNullException

collection or comparer is null.

ArgumentOutOfRangeException

concurrencyLevel is less than 1.

ArgumentException

collection contains one or more duplicate keys.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary

ConcurrentDictionary<TKey,TValue>(Int32, Int32, IEqualityComparer<TKey>)

Source:

ConcurrentDictionary.cs

Initializes a new instance of the ConcurrentDictionary<TKey,TValue> class that is empty, has the specified concurrency level, has the specified initial capacity, and uses the specified IEqualityComparer<T>.

public:
 ConcurrentDictionary(int concurrencyLevel, int capacity, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public ConcurrentDictionary (int concurrencyLevel, int capacity, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

new System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value> : int * int * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Concurrent.ConcurrentDictionary<'Key, 'Value>

Public Sub New (concurrencyLevel As Integer, capacity As Integer, comparer As IEqualityComparer(Of TKey))

Parameters

concurrencyLevel

Int32

The estimated number of threads that will update the ConcurrentDictionary<TKey,TValue> concurrently, or in .NET 8+ only, -1 to indicate the default concurrency level.

capacity

Int32

The initial number of elements that the ConcurrentDictionary<TKey,TValue> can contain.

comparer

IEqualityComparer<TKey>

The IEqualityComparer<T> implementation to use when comparing keys.

Exceptions

ArgumentNullException

comparer is null.

ArgumentOutOfRangeException

concurrencyLevel or capacity is less than 1.

See also

• Thread-Safe Collections
• How to: Add and Remove Items from a ConcurrentDictionary