# SynchronizedList\<T>

Namespace: **Wisej.Core**

Assembly: **Wisej.Framework** (4.0.0.0)

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

{% tabs %}
{% tab title="C#" %}

```csharp
public class SynchronizedList<T> : IList<T>, ICollection<T>, IEnumerable<T>, IEnumerable, IList, ICollection
```

{% endtab %}

{% tab title="VB.NET" %}

```visual-basic
Public Class SynchronizedList(Of T)
    Inherits IList(Of T)
    Implements ICollection(Of T), IEnumerable(Of T), IEnumerable, IList, ICollection
```

{% endtab %}
{% endtabs %}

## Parameters

| Name  | Description                                                          |
| ----- | -------------------------------------------------------------------- |
| **T** | The type of object contained as items in the thread-safe collection. |

## Constructors

### ![](/files/hsR4ok3152WyAf8J2C1u) SynchronizedList(capacity, collection, syncLock)

Initializes a new instance of the [SynchronizedList](https://github.com/iceteagroup/wisej-docs-api/blob/v4.0/api?q=wisej.core.synchronizedlist%601) class that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied and uses the specified *syncLock* object to synchronize its internal operations.

| Name           | Type                                                                                              | Description                                                        |
| -------------- | ------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------ |
| **capacity**   | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)                                       | The optional number of element that the list can initially store.  |
| **collection** | [IEnumerable\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.ienumerable-1) | The optional collection whose elements are copied to the new list. |
| **syncLock**   | [Object](https://docs.microsoft.com/dotnet/api/system.object)                                     | The optional lock reference.                                       |

## Properties

### ![](/files/hsR4ok3152WyAf8J2C1u) Count

[Int32](https://docs.microsoft.com/dotnet/api/system.int32): Gets the number of elements contained in the thread-safe collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) Item(index)

[T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md): Gets an element from the thread-safe collection with a specified index.

**Throws:**

* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) The *index* specified is less than zero or greater than the number of items in the collection.

### ![](/files/lzopMboA31bVq8UIcbT3) Items

[IList\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.ilist-1): Gets the list of elements contained in the thread-safe collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) SyncRoot

[Object](https://docs.microsoft.com/dotnet/api/system.object): Gets the object used to synchronize access to the thread-safe collection.

## Methods

### ![](/files/hsR4ok3152WyAf8J2C1u) Add(item)

Adds an item to the thread-safe collection.

| Parameter | Type                                                                                 | Description                                |
| --------- | ------------------------------------------------------------------------------------ | ------------------------------------------ |
| **item**  | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | The element to be added to the collection. |

### ![](/files/hsR4ok3152WyAf8J2C1u) AddRange(collection)

Adds the elements of the specified collection to the end of the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter      | Type                                                                                              | Description                                                                                                                                                                                                                                            |
| -------------- | ------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **collection** | [IEnumerable\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.ienumerable-1) | The collection whose elements should be added to the end of the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1). The collection itself cannot be null, but it can contain elements that are null, for reference types. |

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *collection* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) BinarySearch(item)

Searches the entire sorted [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) for an element using the default comparer and returns the zero-based index of the element.

| Parameter | Type                                                                                 | Description                                                      |
| --------- | ------------------------------------------------------------------------------------ | ---------------------------------------------------------------- |
| **item**  | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | The object to locate. The value can be null for reference types. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of *item* in the sorted [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1), if *item* is found; otherwise, a negative number that is the bitwise complement of the index of the next element that is larger than *item* or, if there is no larger element, the bitwise complement of [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

**Throws:**

* [InvalidOperationException](https://docs.microsoft.com/dotnet/api/system.invalidoperationexception) The default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1) cannot find an implementation of the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) generic interface or the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) interface for the type of the collection elements.

### ![](/files/hsR4ok3152WyAf8J2C1u) BinarySearch(item, comparer)

Searches the entire sorted [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) for an element using the specified comparer and returns the zero-based index of the element.

| Parameter    | Type                                                                                          | Description                                                                                                                                                                                                                                                               |
| ------------ | --------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **item**     | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md)          | The object to locate. The value can be null for reference types.                                                                                                                                                                                                          |
| **comparer** | [IComparer\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.icomparer-1) | The [IComparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.icomparer-1) implementation to use when comparing elements; or null to use the default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1). |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of *item* in the sorted [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1), if *item* is found; otherwise, a negative number that is the bitwise complement of the index of the next element that is larger than *item* or, if there is no larger element, the bitwise complement of [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

**Throws:**

* [InvalidOperationException](https://docs.microsoft.com/dotnet/api/system.invalidoperationexception) *comparer* is null, and the default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1) cannot find an implementation of the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) generic interface or the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) interface for the type of the collection elements.

### ![](/files/hsR4ok3152WyAf8J2C1u) Clear()

Removes all items from the collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) Contains(item)

Determines whether the collection contains an element with a specific value.

| Parameter | Type                                                                                 | Description                             |
| --------- | ------------------------------------------------------------------------------------ | --------------------------------------- |
| **item**  | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | The object to locate in the collection. |

**Returns:** [Boolean](https://docs.microsoft.com/dotnet/api/system.boolean). true if the element value is found in the collection; otherwise false.

### ![](/files/hsR4ok3152WyAf8J2C1u) CopyTo(array, index)

Copies the elements of the collection to a specified array, starting at a particular index.

| Parameter | Type                                                                                     | Description                                                                                                              |
| --------- | ---------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ |
| **array** | [T\[\]](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | The destination [Array](https://docs.microsoft.com/dotnet/api/system.array) for the elements copied from the collection. |
| **index** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)                              | The zero-based index in the array at which copying begins.                                                               |

### ![](/files/hsR4ok3152WyAf8J2C1u) Find(match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter | Type                                                                      | Description                                                                                                                                  |
| --------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **match** | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md). The first element that matches the conditions defined by the specified predicate, if found; otherwise, the default value.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) Find(startIndex, match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter      | Type                                                                      | Description                                                                                                                                  |
| -------------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **startIndex** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)               | The zero-based starting index of the search.                                                                                                 |
| **match**      | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md). The first element that matches the conditions defined by the specified predicate, if found; otherwise, the default value.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.
* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) *startIndex* is outside the range of valid indexes for the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) FindAll(match)

Retrieves all the elements that match the conditions defined by the specified predicate.

| Parameter | Type                                                                      | Description                                                                                                                                   |
| --------- | ------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| **match** | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the elements to search for. |

**Returns:** [List\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1). A [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) containing all the elements that match the conditions defined by the specified predicate, if found; otherwise, an empty [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) FindIndex(match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter | Type                                                                      | Description                                                                                                                                  |
| --------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **match** | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of the first occurrence of an element that matches the conditions defined by *match* , if found; otherwise, –1.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) FindIndex(startIndex, match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) that extends from the specified index to the last element.

| Parameter      | Type                                                                      | Description                                                                                                                                  |
| -------------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **startIndex** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)               | The zero-based starting index of the search.                                                                                                 |
| **match**      | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of the first occurrence of an element that matches the conditions defined by *match* , if found; otherwise, –1.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.
* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) *startIndex* is outside the range of valid indexes for the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) FindIndex(startIndex, count, match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) that starts at the specified index and contains the specified number of elements.

| Parameter      | Type                                                                      | Description                                                                                                                                  |
| -------------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **startIndex** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)               | The zero-based starting index of the search.                                                                                                 |
| **count**      | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)               | The number of elements in the section to search.                                                                                             |
| **match**      | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of the first occurrence of an element that matches the conditions defined by *match* , if found; otherwise, –1.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.
* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) *startIndex* is outside the range of valid indexes for the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1); or *count* is less than 0; or *startIndex* and *count* do not specify a valid section in the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) FindLast(match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the last occurrence within the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter | Type                                                                      | Description                                                                                                                                  |
| --------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **match** | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md). The last element that matches the conditions defined by the specified predicate, if found; otherwise, the default value.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) FindLast(startIndex, match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the last occurrence within the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter      | Type                                                                      | Description                                                                                                                                  |
| -------------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **startIndex** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)               | The zero-based starting index of the search.                                                                                                 |
| **match**      | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md). The last element that matches the conditions defined by the specified predicate, if found; otherwise, the default value.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.
* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) *startIndex* is outside the range of valid indexes for the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) FindLastIndex(match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter | Type                                                                      | Description                                                                                                                                  |
| --------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **match** | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of the last occurrence of an element that matches the conditions defined by *match* , if found; otherwise, –1.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) FindLastIndex(startIndex, match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) that extends from the specified index to the last element.

| Parameter      | Type                                                                      | Description                                                                                                                                  |
| -------------- | ------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **startIndex** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)               | The zero-based starting index of the search.                                                                                                 |
| **match**      | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the element to search for. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of the last occurrence of an element that matches the conditions defined by *match* , if found; otherwise, –1.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.
* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) *startIndex* is outside the range of valid indexes for the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) ForEach(action)

Performs the specified action on each element of the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

| Parameter  | Type                                                                | Description                                                                                                                                                                                   |
| ---------- | ------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **action** | [Action\<T>](https://docs.microsoft.com/dotnet/api/system.action-1) | The [Action](https://docs.microsoft.com/dotnet/api/system.action) delegate to perform on each element of the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1). |

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *action* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) GetEnumerator()

Returns an enumerator that iterates through the synchronized collection.

**Returns:** [IEnumerator\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.ienumerator-1). An [IEnumerator](https://docs.microsoft.com/dotnet/api/system.collections.generic.ienumerator-1) for objects of the type stored in the collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) IndexOf(item)

Returns the index of the first occurrence of a value in the collection.

| Parameter | Type                                                                                 | Description                            |
| --------- | ------------------------------------------------------------------------------------ | -------------------------------------- |
| **item**  | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | Removes all items from the collection. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The zero-based index of the first occurrence of the value in the collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) Insert(index, item)

Inserts an item into the collection at a specified index.

| Parameter | Type                                                                                 | Description                                                              |
| --------- | ------------------------------------------------------------------------------------ | ------------------------------------------------------------------------ |
| **index** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)                          | The zero-based index of the element to be retrieved from the collection. |
| **item**  | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | The object to be inserted into the collection as an element.             |

**Throws:**

* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) The *index* specified is less than zero or greater than the number of items in the collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) InsertRange(index, collection)

Inserts the elements of a collection into the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) at the specified index.

| Parameter      | Type                                                                                              | Description                                                                                                                                                                                                                                      |
| -------------- | ------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **index**      | [Int32](https://docs.microsoft.com/dotnet/api/system.int32)                                       | The zero-based index at which the new elements should be inserted.                                                                                                                                                                               |
| **collection** | [IEnumerable\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.ienumerable-1) | The collection whose elements should be inserted into the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1). The collection itself cannot be null, but it can contain elements that are null, for reference types. |

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *collection* is null.
* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) *index* is less than 0; or *index* is greater than [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) Remove(item)

Removes the first occurrence of a specified item from the collection.

| Parameter | Type                                                                                 | Description                               |
| --------- | ------------------------------------------------------------------------------------ | ----------------------------------------- |
| **item**  | [T](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md) | The object to remove from the collection. |

**Returns:** [Boolean](https://docs.microsoft.com/dotnet/api/system.boolean). true if item was successfully removed from the collection; otherwise, false.

### ![](/files/hsR4ok3152WyAf8J2C1u) RemoveAll(match)

Removes all the elements that match the conditions defined by the specified predicate.

| Parameter | Type                                                                      | Description                                                                                                                               |
| --------- | ------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| **match** | [Predicate\<T>](https://docs.microsoft.com/dotnet/api/system.predicate-1) | The [Predicate](https://docs.microsoft.com/dotnet/api/system.predicate-1) delegate that defines the conditions of the elements to remove. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The number of elements removed from the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) .

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *match* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) RemoveAt(index)

Removes an item at a specified index from the collection.

| Parameter | Type                                                        | Description                                                              |
| --------- | ----------------------------------------------------------- | ------------------------------------------------------------------------ |
| **index** | [Int32](https://docs.microsoft.com/dotnet/api/system.int32) | The zero-based index of the element to be retrieved from the collection. |

**Throws:**

* [ArgumentOutOfRangeException](https://docs.microsoft.com/dotnet/api/system.argumentoutofrangeexception) The *index* specified is less than zero or greater than the number of items in the collection.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sort()

Sorts the elements in the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) using the default comparer.

**Throws:**

* [InvalidOperationException](https://docs.microsoft.com/dotnet/api/system.invalidoperationexception) The default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1) cannot find an implementation of the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) generic interface or the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) interface for the type of the collection elements.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sort(comparer)

Sorts the elements in the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) using the specified comparer.

| Parameter    | Type                                                                                          | Description                                                                                                                                                                                                                                                               |
| ------------ | --------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **comparer** | [IComparer\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.icomparer-1) | The [IComparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.icomparer-1) implementation to use when comparing elements, or null to use the default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1). |

**Throws:**

* [InvalidOperationException](https://docs.microsoft.com/dotnet/api/system.invalidoperationexception) *comparer* is null, and the default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1) cannot find implementation of the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) generic interface or the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) interface for the type of the collection elements.
* [ArgumentException](https://docs.microsoft.com/dotnet/api/system.argumentexception) The implementation of *comparer* caused an error during the sort. For example, *comparer* might not return 0 when comparing an item with itself.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sort(comparison)

Sorts the elements in the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) using the specified [Comparison](https://docs.microsoft.com/dotnet/api/system.comparison-1).

| Parameter      | Type                                                                        | Description                                                                                                 |
| -------------- | --------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------- |
| **comparison** | [Comparison\<T>](https://docs.microsoft.com/dotnet/api/system.comparison-1) | The [Comparison](https://docs.microsoft.com/dotnet/api/system.comparison-1) to use when comparing elements. |

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *comparison* is null.
* [ArgumentException](https://docs.microsoft.com/dotnet/api/system.argumentexception) The implementation of *comparison* caused an error during the sort. For example, *comparison* might not return 0 when comparing an item with itself.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sort(comparer, swapCallback)

Sorts the elements in the entire [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) using the specified comparer and a related [IList](https://docs.microsoft.com/dotnet/api/system.collections.ilist) to sort in sync with this collection.

| Parameter                                         | Type                                                                                          | Description                                                                                                                                                                                                                                                               |
| ------------------------------------------------- | --------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **comparer**                                      | [IComparer\<T>](https://docs.microsoft.com/dotnet/api/system.collections.generic.icomparer-1) | The [IComparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.icomparer-1) implementation to use when comparing elements, or null to use the default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1). |
| **swapCallback** ![](/files/1vGqtbG2j637vQ4ROWOf) | [Func\<Int32, Int32, Boolean>](https://docs.microsoft.com/dotnet/api/system.func-3)           | An optional callback method, invoked on every swap. If the callback returns true to indicate that it handled the swap, the default swap is not performed.                                                                                                                 |

**Throws:**

* [InvalidOperationException](https://docs.microsoft.com/dotnet/api/system.invalidoperationexception) *comparer* is null, and the default comparer [Comparer](https://docs.microsoft.com/dotnet/api/system.collections.generic.comparer-1) cannot find implementation of the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) generic interface or the [IComparable](https://docs.microsoft.com/dotnet/api/system.icomparable) interface for the type of the collection elements.
* [ArgumentException](https://docs.microsoft.com/dotnet/api/system.argumentexception) The implementation of *comparer* caused an error during the sort. For example, *comparer* might not return 0 when comparing an item with itself.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sum(selector)

Computes the sum of the sequence of System.Int32 values that are obtained by invoking a transform function on each element of the list.

| Parameter    | Type                                                                   | Description                                    |
| ------------ | ---------------------------------------------------------------------- | ---------------------------------------------- |
| **selector** | [Func\<T, Int32>](https://docs.microsoft.com/dotnet/api/system.func-2) | A transform function to apply to each element. |

**Returns:** [Int32](https://docs.microsoft.com/dotnet/api/system.int32). The sum of the returned values.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *selector* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sum(selector)

Computes the sum of the sequence of System.Int64 values that are obtained by invoking a transform function on each element of the list.

| Parameter    | Type                                                                   | Description                                    |
| ------------ | ---------------------------------------------------------------------- | ---------------------------------------------- |
| **selector** | [Func\<T, Int64>](https://docs.microsoft.com/dotnet/api/system.func-2) | A transform function to apply to each element. |

**Returns:** [Int64](https://docs.microsoft.com/dotnet/api/system.int64). The sum of the returned values.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *selector* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sum(selector)

Computes the sum of the sequence of System.Single values that are obtained by invoking a transform function on each element of the list.

| Parameter    | Type                                                                    | Description                                    |
| ------------ | ----------------------------------------------------------------------- | ---------------------------------------------- |
| **selector** | [Func\<T, Single>](https://docs.microsoft.com/dotnet/api/system.func-2) | A transform function to apply to each element. |

**Returns:** [Single](https://docs.microsoft.com/dotnet/api/system.single). The sum of the returned values.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *selector* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sum(selector)

Computes the sum of the sequence of System.Double values that are obtained by invoking a transform function on each element of the list.

| Parameter    | Type                                                                    | Description                                    |
| ------------ | ----------------------------------------------------------------------- | ---------------------------------------------- |
| **selector** | [Func\<T, Double>](https://docs.microsoft.com/dotnet/api/system.func-2) | A transform function to apply to each element. |

**Returns:** [Double](https://docs.microsoft.com/dotnet/api/system.double). The sum of the returned values.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *selector* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) Sum(selector)

Computes the sum of the sequence of System.Decimal values that are obtained by invoking a transform function on each element of the list.

| Parameter    | Type                                                                     | Description                                    |
| ------------ | ------------------------------------------------------------------------ | ---------------------------------------------- |
| **selector** | [Func\<T, Decimal>](https://docs.microsoft.com/dotnet/api/system.func-2) | A transform function to apply to each element. |

**Returns:** [Decimal](https://docs.microsoft.com/dotnet/api/system.decimal). The sum of the returned values.

**Throws:**

* [ArgumentNullException](https://docs.microsoft.com/dotnet/api/system.argumentnullexception) *selector* is null.

### ![](/files/hsR4ok3152WyAf8J2C1u) ToArray()

Copies the elements of the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1) to a new array.

**Returns:** [T\[\]](/api/wisej.core/general/wisej.core.synchronizedlist-less-than-t-greater-than.md). An array containing copies of the elements of the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1).

### ![](/files/hsR4ok3152WyAf8J2C1u) TrimExcess()

Sets the capacity to the actual number of elements in the [List](https://docs.microsoft.com/dotnet/api/system.collections.generic.list-1), if that number is less than a threshold value.


---

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