HashSet<T> 建構函式

參考

定義

命名空間:: System.Collections.Generic

組件:: System.Collections.dll

組件:: System.Core.dll

組件:: netstandard.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

初始化 HashSet<T> 類別的新執行個體。

多載

HashSet<T>()	初始化 HashSet<T> 類別的新執行個體，這個執行個體是空白的，並使用集合類型的預設相等比較子。
HashSet<T>(IEnumerable<T>)	初始化 HashSet<T> 類別的新執行個體，這個執行個體使用集合類型的預設相等比較子、包含從指定之集合複製的項目，並具有足以容納所複製項目數的容量。
HashSet<T>(IEqualityComparer<T>)	初始化 HashSet<T> 類別的新執行個體，這個執行個體是空白的，並使用集合類型的指定相等比較子。
HashSet<T>(Int32)	將 HashSet<T> 類別的新執行個體初始化，該類別為空白，但為 `capacity` 項目保留了空間，並對集合類型使用預設相等比較子。
HashSet<T>(IEnumerable<T>, IEqualityComparer<T>)	初始化 HashSet<T> 類別的新執行個體，這個執行個體使用集合類型的指定相等比較子、包含從指定之集合複製的項目，並具有足以容納所複製項目數的容量。
HashSet<T>(Int32, IEqualityComparer<T>)	將 HashSet<T> 類別的新執行個體初始化，該類別對集合類型使用指定的相等比較子，並擁有足夠容量容納 `capacity` 元素。
HashSet<T>(SerializationInfo, StreamingContext)	已淘汰. 使用序列化資料，初始化 HashSet<T> 類別的新執行個體。

HashSet<T>()

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

初始化 HashSet<T> 類別的新執行個體，這個執行個體是空白的，並使用集合類型的預設相等比較子。

public:
 HashSet();

public HashSet ();

Public Sub New ()

範例

下列範例示範如何建立和填入兩 HashSet<T> 個物件。這個範例是針對方法提供的較大範例的 UnionWith 一部分。

HashSet<int> evenNumbers = new HashSet<int>();
HashSet<int> oddNumbers = new HashSet<int>();

for (int i = 0; i < 5; i++)
{
    // Populate numbers with just even numbers.
    evenNumbers.Add(i * 2);

    // Populate oddNumbers with just odd numbers.
    oddNumbers.Add((i * 2) + 1);
}

Dim evenNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()
Dim oddNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()

For i As Integer = 0 To 4

    ' Populate evenNumbers with only even numbers.
    evenNumbers.Add(i * 2)

    ' Populate oddNumbers with only odd numbers.
    oddNumbers.Add((i * 2) + 1)
Next i

備註

物件的容量 HashSet<T> 是物件可以保存的元素數目。物件 HashSet<T> 容量會自動增加，因為專案會加入物件中。

此建構函式是 O (1) 作業。

適用於

HashSet<T>(IEnumerable<T>)

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

初始化 HashSet<T> 類別的新執行個體，這個執行個體使用集合類型的預設相等比較子、包含從指定之集合複製的項目，並具有足以容納所複製項目數的容量。

public:
 HashSet(System::Collections::Generic::IEnumerable<T> ^ collection);

public HashSet (System.Collections.Generic.IEnumerable<T> collection);

new System.Collections.Generic.HashSet<'T> : seq<'T> -> System.Collections.Generic.HashSet<'T>

Public Sub New (collection As IEnumerable(Of T))

參數

collection: IEnumerable<T>

集合 (Collection)，其項目會複製到新的集合 (Set)。

例外狀況

ArgumentNullException

collection 為 null。

範例

下列範例示範如何從現有的集合建立 HashSet<T> 集合。在此範例中，會分別使用偶數和奇數整數來建立兩個集合。接著會從偶數整數集建立第三 HashSet<T> 個物件。

HashSet<int> evenNumbers = new HashSet<int>();
HashSet<int> oddNumbers = new HashSet<int>();

for (int i = 0; i < 5; i++)
{
    // Populate numbers with just even numbers.
    evenNumbers.Add(i * 2);

    // Populate oddNumbers with just odd numbers.
    oddNumbers.Add((i * 2) + 1);
}

Console.Write("evenNumbers contains {0} elements: ", evenNumbers.Count);
DisplaySet(evenNumbers);

Console.Write("oddNumbers contains {0} elements: ", oddNumbers.Count);
DisplaySet(oddNumbers);

// Create a new HashSet populated with even numbers.
HashSet<int> numbers = new HashSet<int>(evenNumbers);
Console.WriteLine("numbers UnionWith oddNumbers...");
numbers.UnionWith(oddNumbers);

Console.Write("numbers contains {0} elements: ", numbers.Count);
DisplaySet(numbers);

void DisplaySet(HashSet<int> collection)
{
    Console.Write("{");
    foreach (int i in collection)
    {
        Console.Write(" {0}", i);
    }
    Console.WriteLine(" }");
}

/* This example produces output similar to the following:
* evenNumbers contains 5 elements: { 0 2 4 6 8 }
* oddNumbers contains 5 elements: { 1 3 5 7 9 }
* numbers UnionWith oddNumbers...
* numbers contains 10 elements: { 0 2 4 6 8 1 3 5 7 9 }
*/

Shared Sub Main()

    Dim evenNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()
    Dim oddNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()

    For i As Integer = 0 To 4

        ' Populate evenNumbers with only even numbers.
        evenNumbers.Add(i * 2)

        ' Populate oddNumbers with only odd numbers.
        oddNumbers.Add((i * 2) + 1)
    Next i

    Console.Write("evenNumbers contains {0} elements: ", evenNumbers.Count)
    DisplaySet(evenNumbers)

    Console.Write("oddNumbers contains {0} elements: ", oddNumbers.Count)
    DisplaySet(oddNumbers)

    ' Create a new HashSet populated with even numbers.
    Dim numbers As HashSet(Of Integer) = New HashSet(Of Integer)(evenNumbers)
    Console.WriteLine("numbers UnionWith oddNumbers...")
    numbers.UnionWith(oddNumbers)

    Console.Write("numbers contains {0} elements: ", numbers.Count)
    DisplaySet(numbers)
End Sub

備註

物件的容量 HashSet<T> 是物件可以保存的元素數目。物件 HashSet<T> 容量會自動增加，因為專案會加入物件中。

如果 collection 包含重複專案，則集合將包含每個唯一元素之一。不會擲回例外狀況。因此，產生的集大小與的大小 collection 不相同。

這個建構函式是 O (n) 作業，其中 n 是參數中的 collection 元素數目。

適用於

HashSet<T>(IEqualityComparer<T>)

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

初始化 HashSet<T> 類別的新執行個體，這個執行個體是空白的，並使用集合類型的指定相等比較子。

public:
 HashSet(System::Collections::Generic::IEqualityComparer<T> ^ comparer);

public HashSet (System.Collections.Generic.IEqualityComparer<T> comparer);

public HashSet (System.Collections.Generic.IEqualityComparer<T>? comparer);

new System.Collections.Generic.HashSet<'T> : System.Collections.Generic.IEqualityComparer<'T> -> System.Collections.Generic.HashSet<'T>

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

參數

comparer: IEqualityComparer<T>

在集合中比較各個值時所要使用的 IEqualityComparer<T> 實作；若要針對集合類型使用預設 EqualityComparer<T> 實作，則為 null。

備註

物件的容量 HashSet<T> 是物件可以保存的元素數目。物件 HashSet<T> 容量會自動增加，因為專案會加入物件中。

此建構函式是 O (1) 作業。

適用於

HashSet<T>(Int32)

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

將 HashSet<T> 類別的新執行個體初始化，該類別為空白，但為 capacity 項目保留了空間，並對集合類型使用預設相等比較子。

public:
 HashSet(int capacity);

public HashSet (int capacity);

new System.Collections.Generic.HashSet<'T> : int -> System.Collections.Generic.HashSet<'T>

Public Sub New (capacity As Integer)

參數

capacity: Int32

的初始大小 HashSet<T> 。

備註

由於調整大小的成本相對昂貴， (需要重新套用) ，因此這會嘗試根據的值 capacity 設定初始容量來最小化調整大小的需求。

適用於

HashSet<T>(IEnumerable<T>, IEqualityComparer<T>)

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

初始化 HashSet<T> 類別的新執行個體，這個執行個體使用集合類型的指定相等比較子、包含從指定之集合複製的項目，並具有足以容納所複製項目數的容量。

public:
 HashSet(System::Collections::Generic::IEnumerable<T> ^ collection, System::Collections::Generic::IEqualityComparer<T> ^ comparer);

public HashSet (System.Collections.Generic.IEnumerable<T> collection, System.Collections.Generic.IEqualityComparer<T> comparer);

public HashSet (System.Collections.Generic.IEnumerable<T> collection, System.Collections.Generic.IEqualityComparer<T>? comparer);

new System.Collections.Generic.HashSet<'T> : seq<'T> * System.Collections.Generic.IEqualityComparer<'T> -> System.Collections.Generic.HashSet<'T>

Public Sub New (collection As IEnumerable(Of T), comparer As IEqualityComparer(Of T))

參數

collection: IEnumerable<T>

集合 (Collection)，其項目會複製到新的集合 (Set)。

comparer: IEqualityComparer<T>

在集合中比較各個值時所要使用的 IEqualityComparer<T> 實作；若要針對集合類型使用預設 EqualityComparer<T> 實作，則為 null。

例外狀況

ArgumentNullException

collection 為 null。

範例

下列範例會使用提供的 IEqualityComparer<T> 來允許不區分大小寫的車輛類型集合專案 HashSet<T> 比較。

#using <System.Core.dll>

using namespace System;
using namespace System::Collections::Generic;

ref class Program
{
public:
    static void Main()
    {
        HashSet<String^> ^allVehicles = gcnew HashSet<String^>(StringComparer::OrdinalIgnoreCase);
        List<String^>^ someVehicles = gcnew List<String^>();

        someVehicles->Add("Planes");
        someVehicles->Add("Trains");
        someVehicles->Add("Automobiles");

        // Add in the vehicles contained in the someVehicles list.
        allVehicles->UnionWith(someVehicles);

        Console::WriteLine("The current HashSet contains:\n");
        for each (String^ vehicle in allVehicles)
        {
            Console::WriteLine(vehicle);
        }

        allVehicles->Add("Ships");
        allVehicles->Add("Motorcycles");
        allVehicles->Add("Rockets");
        allVehicles->Add("Helicopters");
        allVehicles->Add("Submarines");

        Console::WriteLine("\nThe updated HashSet contains:\n");
        for each (String^ vehicle in allVehicles)
        {
            Console::WriteLine(vehicle);
        }

        // Verify that the 'All Vehicles' set contains at least the vehicles in
        // the 'Some Vehicles' list.
        if (allVehicles->IsSupersetOf(someVehicles))
        {
            Console::Write("\nThe 'All' vehicles set contains everything in ");
            Console::WriteLine("'Some' vechicles list.");
        }

        // Check for Rockets. Here the OrdinalIgnoreCase comparer will compare
        // true for the mixed-case vehicle type.
        if (allVehicles->Contains("roCKeTs"))
        {
            Console::WriteLine("\nThe 'All' vehicles set contains 'roCKeTs'");
        }

        allVehicles->ExceptWith(someVehicles);
        Console::WriteLine("\nThe excepted HashSet contains:\n");
        for each (String^ vehicle in allVehicles)
        {
            Console::WriteLine(vehicle);
        }

        // Remove all the vehicles that are not 'super cool'.
        allVehicles->RemoveWhere(gcnew Predicate<String^>(&isNotSuperCool));

        Console::WriteLine("\nThe super cool vehicles are:\n");
        for each (String^ vehicle in allVehicles)
        {
            Console::WriteLine(vehicle);
        }
    }

private:
    // Predicate to determine vehicle 'coolness'.
    static bool isNotSuperCool(String^ vehicle)
    {
        bool superCool = (vehicle == "Helicopters") || (vehicle == "Motorcycles");

        return !superCool;
    }
};

int main()
{
    Program::Main();
}

// The program writes the following output to the console::
//
// The current HashSet contains:
//
// Planes
// Trains
// Automobiles
//
// The updated HashSet contains:
//
// Planes
// Trains
// Automobiles
// Ships
// Motorcycles
// Rockets
// Helicopters
// Submarines
//
// The 'All' vehicles set contains everything in 'Some' vechicles list.
//
// The 'All' vehicles set contains 'roCKeTs'
//
// The excepted HashSet contains:
//
// Ships
// Motorcycles
// Rockets
// Helicopters
// Submarines
//
// The super cool vehicles are:
//
// Motorcycles
// Helicopters

HashSet<string> allVehicles = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
List<string> someVehicles = new List<string>();

someVehicles.Add("Planes");
someVehicles.Add("Trains");
someVehicles.Add("Automobiles");

// Add in the vehicles contained in the someVehicles list.
allVehicles.UnionWith(someVehicles);

Console.WriteLine("The current HashSet contains:\n");
foreach (string vehicle in allVehicles)
{
    Console.WriteLine(vehicle);
}

allVehicles.Add("Ships");
allVehicles.Add("Motorcycles");
allVehicles.Add("Rockets");
allVehicles.Add("Helicopters");
allVehicles.Add("Submarines");

Console.WriteLine("\nThe updated HashSet contains:\n");
foreach (string vehicle in allVehicles)
{
    Console.WriteLine(vehicle);
}

// Verify that the 'All Vehicles' set contains at least the vehicles in
// the 'Some Vehicles' list.
if (allVehicles.IsSupersetOf(someVehicles))
{
    Console.Write("\nThe 'All' vehicles set contains everything in ");
    Console.WriteLine("'Some' vechicles list.");
}

// Check for Rockets. Here the OrdinalIgnoreCase comparer will compare
// true for the mixed-case vehicle type.
if (allVehicles.Contains("roCKeTs"))
{
    Console.WriteLine("\nThe 'All' vehicles set contains 'roCKeTs'");
}

allVehicles.ExceptWith(someVehicles);
Console.WriteLine("\nThe excepted HashSet contains:\n");
foreach (string vehicle in allVehicles)
{
    Console.WriteLine(vehicle);
}

// Remove all the vehicles that are not 'super cool'.
allVehicles.RemoveWhere(isNotSuperCool);

Console.WriteLine("\nThe super cool vehicles are:\n");
foreach (string vehicle in allVehicles)
{
    Console.WriteLine(vehicle);
}

// Predicate to determine vehicle 'coolness'.
bool isNotSuperCool(string vehicle)
{
    bool superCool = (vehicle == "Helicopters") || (vehicle == "Motorcycles");

    return !superCool;
}

// The program writes the following output to the console.
//
// The current HashSet contains:
//
// Planes
// Trains
// Automobiles
//
// The updated HashSet contains:
//
// Planes
// Trains
// Automobiles
// Ships
// Motorcycles
// Rockets
// Helicopters
// Submarines
//
// The 'All' vehicles set contains everything in 'Some' vechicles list.
//
// The 'All' vehicles set contains 'roCKeTs'
//
// The excepted HashSet contains:
//
// Ships
// Motorcycles
// Rockets
// Helicopters
// Submarines
//
// The super cool vehicles are:
//
// Motorcycles
// Helicopters

Imports System.Collections.Generic

Class Program
    Public Shared Sub Main()
        Dim allVehicles As New HashSet(Of String)(StringComparer.OrdinalIgnoreCase)
        Dim someVehicles As New List(Of String)()

        someVehicles.Add("Planes")
        someVehicles.Add("Trains")
        someVehicles.Add("Automobiles")

        ' Add in the vehicles contained in the someVehicles list.
        allVehicles.UnionWith(someVehicles)

        Console.WriteLine("The current HashSet contains:" + Environment.NewLine)
        For Each vehicle As String In allVehicles
            Console.WriteLine(vehicle)
        Next vehicle

        allVehicles.Add("Ships")
        allVehicles.Add("Motorcycles")
        allVehicles.Add("Rockets")
        allVehicles.Add("Helicopters")
        allVehicles.Add("Submarines")

        Console.WriteLine(Environment.NewLine + "The updated HashSet contains:" + Environment.NewLine)
        For Each vehicle As String In allVehicles
            Console.WriteLine(vehicle)
        Next vehicle

        ' Verify that the 'All Vehicles' set contains at least the vehicles in
        ' the 'Some Vehicles' list.
        If allVehicles.IsSupersetOf(someVehicles) Then
            Console.Write(Environment.NewLine + "The 'All' vehicles set contains everything in ")
            Console.WriteLine("'Some' vechicles list.")
        End If

        ' Check for Rockets. Here the OrdinalIgnoreCase comparer will compare
        ' True for the mixed-case vehicle type.
        If allVehicles.Contains("roCKeTs") Then
            Console.WriteLine(Environment.NewLine + "The 'All' vehicles set contains 'roCKeTs'")
        End If

        allVehicles.ExceptWith(someVehicles)
        Console.WriteLine(Environment.NewLine + "The excepted HashSet contains:" + Environment.NewLine)
        For Each vehicle As String In allVehicles
            Console.WriteLine(vehicle)
        Next vehicle

        ' Remove all the vehicles that are not 'super cool'.
        allVehicles.RemoveWhere(AddressOf isNotSuperCool)

        Console.WriteLine(Environment.NewLine + "The super cool vehicles are:" + Environment.NewLine)
        For Each vehicle As String In allVehicles
            Console.WriteLine(vehicle)
        Next vehicle
    End Sub

    ' Predicate to determine vehicle 'coolness'.
    Private Shared Function isNotSuperCool(vehicle As String) As Boolean
        Dim notSuperCool As Boolean = _
            (vehicle <> "Helicopters") And (vehicle <> "Motorcycles")

        Return notSuperCool
    End Function
End Class

'
' The program writes the following output to the console.
'
' The current HashSet contains:
'
' Planes
' Trains
' Automobiles
'
' The updated HashSet contains:
'
' Planes
' Trains
' Automobiles
' Ships
' Motorcycles
' Rockets
' Helicopters
' Submarines
'
' The 'All' vehicles set contains everything in 'Some' vechicles list.
'
' The 'All' vehicles set contains 'roCKeTs'
'
' The excepted HashSet contains:
'
' Ships
' Motorcycles
' Rockets
' Helicopters
' Submarines
'
' The super cool vehicles are:
'
' Motorcycles
' Helicopters

備註

物件的容量 HashSet<T> 是物件可以保存的元素數目。物件 HashSet<T> 容量會自動增加，因為專案會加入物件中。

如果 collection 包含重複專案，則集合將包含每個唯一元素之一。不會擲回例外狀況。因此，產生的集大小與的大小 collection 不相同。

這個建構函式是 O (n) 作業，其中 n 是參數中的 collection 元素數目。

適用於

HashSet<T>(Int32, IEqualityComparer<T>)

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

將 HashSet<T> 類別的新執行個體初始化，該類別對集合類型使用指定的相等比較子，並擁有足夠容量容納 capacity 元素。

public:
 HashSet(int capacity, System::Collections::Generic::IEqualityComparer<T> ^ comparer);

public HashSet (int capacity, System.Collections.Generic.IEqualityComparer<T>? comparer);

public HashSet (int capacity, System.Collections.Generic.IEqualityComparer<T> comparer);

new System.Collections.Generic.HashSet<'T> : int * System.Collections.Generic.IEqualityComparer<'T> -> System.Collections.Generic.HashSet<'T>

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

參數

capacity: Int32

的初始大小 HashSet<T> 。

comparer: IEqualityComparer<T>

在集合中比較各個值時所要使用的 IEqualityComparer<T> 實作；或針對集合類型使用預設 IEqualityComparer<T> 實作，則為 Null (Visual Basic 為 Nothing)。

備註

由於調整大小的成本相對昂貴， (需要重新套用) ，因此這會嘗試根據的值 capacity 設定初始容量來最小化調整大小的需求。

適用於

HashSet<T>(SerializationInfo, StreamingContext)

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

警告

This API supports obsolete formatter-based serialization. It should not be called or extended by application code.

使用序列化資料，初始化 HashSet<T> 類別的新執行個體。

protected:
 HashSet(System::Runtime::Serialization::SerializationInfo ^ info, System::Runtime::Serialization::StreamingContext context);

protected HashSet (System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context);

[System.Obsolete("This API supports obsolete formatter-based serialization. It should not be called or extended by application code.", DiagnosticId="SYSLIB0051", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
protected HashSet (System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context);

new System.Collections.Generic.HashSet<'T> : System.Runtime.Serialization.SerializationInfo * System.Runtime.Serialization.StreamingContext -> System.Collections.Generic.HashSet<'T>

[<System.Obsolete("This API supports obsolete formatter-based serialization. It should not be called or extended by application code.", DiagnosticId="SYSLIB0051", UrlFormat="https://aka.ms/dotnet-warnings/{0}")>]
new System.Collections.Generic.HashSet<'T> : System.Runtime.Serialization.SerializationInfo * System.Runtime.Serialization.StreamingContext -> System.Collections.Generic.HashSet<'T>

Protected Sub New (info As SerializationInfo, context As StreamingContext)

參數

info: SerializationInfo

SerializationInfo 物件，包含序列化 HashSet<T> 物件所需的資訊。

context: StreamingContext

StreamingContext 結構，包含與 HashSet<T> 物件相關聯之已序列化資料流的來源和目的地。

屬性: ObsoleteAttribute

備註

還原序列化期間會呼叫這個建構函式，以重新建構透過資料流程傳輸的物件。如需詳細資訊，請參閱 < XML 和 SOAP 序列化。

適用於

HashSet<T> 建構函式

定義

多載

HashSet<T>()

範例

備註

適用於

HashSet<T>(IEnumerable<T>)

參數

例外狀況

範例

備註

適用於

HashSet<T>(IEqualityComparer<T>)

參數

備註

適用於

HashSet<T>(Int32)

參數

備註

適用於

HashSet<T>(IEnumerable<T>, IEqualityComparer<T>)

參數

例外狀況

範例

備註

適用於

HashSet<T>(Int32, IEqualityComparer<T>)

參數

備註

適用於

HashSet<T>(SerializationInfo, StreamingContext)

參數

備註

適用於

意見反應

其他資源