HashSet<T> 类

定义

generic <typename T>
public ref class HashSet : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IReadOnlyCollection<T>, System::Collections::Generic::ISet<T>

generic <typename T>
public ref class HashSet : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IReadOnlyCollection<T>, System::Collections::Generic::IReadOnlySet<T>, System::Collections::Generic::ISet<T>, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

generic <typename T>
public ref class HashSet : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IReadOnlyCollection<T>, System::Collections::Generic::ISet<T>, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

generic <typename T>
public ref class HashSet : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

generic <typename T>
public ref class HashSet : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::ISet<T>, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

generic <typename T>
public ref class HashSet : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::ISet<T>

public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.ISet<T>

public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlySet<T>, System.Collections.Generic.ISet<T>, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.ISet<T>, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.ISet<T>, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.ISet<T>, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

public class HashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.ISet<T>

type HashSet<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface IReadOnlyCollection<'T>
    interface ISet<'T>

type HashSet<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface IReadOnlyCollection<'T>
    interface ISet<'T>
    interface IReadOnlySet<'T>
    interface IDeserializationCallback
    interface ISerializable

type HashSet<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface IReadOnlyCollection<'T>
    interface ISet<'T>
    interface IDeserializationCallback
    interface ISerializable

[<System.Serializable>]
type HashSet<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface ISerializable
    interface IDeserializationCallback

[<System.Serializable>]
type HashSet<'T> = class
    interface ISerializable
    interface IDeserializationCallback
    interface ISet<'T>
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable

[<System.Serializable>]
type HashSet<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface ISerializable
    interface IDeserializationCallback
    interface ISet<'T>
    interface IReadOnlyCollection<'T>

type HashSet<'T> = class
    interface ISet<'T>
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable

Public Class HashSet(Of T)
Implements ICollection(Of T), IEnumerable(Of T), IReadOnlyCollection(Of T), ISet(Of T)

Public Class HashSet(Of T)
Implements ICollection(Of T), IDeserializationCallback, IEnumerable(Of T), IReadOnlyCollection(Of T), IReadOnlySet(Of T), ISerializable, ISet(Of T)

Public Class HashSet(Of T)
Implements ICollection(Of T), IDeserializationCallback, IEnumerable(Of T), IReadOnlyCollection(Of T), ISerializable, ISet(Of T)

Public Class HashSet(Of T)
Implements ICollection(Of T), IDeserializationCallback, IEnumerable(Of T), ISerializable

Public Class HashSet(Of T)
Implements ICollection(Of T), IDeserializationCallback, IEnumerable(Of T), ISerializable, ISet(Of T)

Public Class HashSet(Of T)
Implements ICollection(Of T), IEnumerable(Of T), ISet(Of T)

类型参数

继承

Object

HashSet<T>

属性

SerializableAttribute

实现

ICollection<T> IEnumerable<T> IReadOnlyCollection<T> ISet<T> IEnumerable IReadOnlySet<T> IDeserializationCallback ISerializable

示例

以下示例演示如何合并两个不同的集。 此示例创建两个 HashSet<T> 对象，并分别使用偶数和奇数填充它们。 从包含偶数的集创建第三 HashSet<T> 个对象。 然后，该示例调用 UnionWith 该方法，该方法将奇数集添加到第三组。

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 }
*/

let displaySet (collection: HashSet<int>) =
    printf "{"

    for i in collection do
        printf $" {i}"

    printfn " }"

let evenNumbers = HashSet<int>()
let oddNumbers = HashSet<int>()

for i = 0 to 4 do
    // Populate numbers with just even numbers.
    evenNumbers.Add(i * 2) |> ignore

    // Populate oddNumbers with just odd numbers.
    oddNumbers.Add(i * 2 + 1) |> ignore

printf $"evenNumbers contains {evenNumbers.Count} elements: "
displaySet evenNumbers

printf $"oddNumbers contains {oddNumbers.Count} elements: "
displaySet oddNumbers

// Create a new HashSet populated with even numbers.
let numbers = HashSet<int> evenNumbers
printfn "numbers UnionWith oddNumbers..."
numbers.UnionWith oddNumbers

printf $"numbers contains {numbers.Count} elements: "
displaySet numbers
// 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 }

Imports System.Collections.Generic

Class Program

    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


    Private Shared Sub DisplaySet(ByVal collection As HashSet(Of Integer))
        Console.Write("{")
        For Each i As Integer In collection
            Console.Write(" {0}", i)
        Next i
        Console.WriteLine(" }")
    End Sub

End Class
' 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 }

注解

该 HashSet<T> 类提供高性能集合运算。 集是一个集合，其中包含不重复的元素，并且其元素没有特定顺序。

对象的容量 HashSet<T> 是对象可以保存的元素数。 随着 HashSet<T> 元素添加到对象中，对象的容量会自动增加。

该HashSet<T>类基于数学集的模型，并提供类似于访问Dictionary<TKey,TValue>或Hashtable集合键的高性能集合操作。 简单而言， HashSet<T> 类可以视为 Dictionary<TKey,TValue> 没有值的集合。

HashSet<T>集合未排序，并且不能包含重复的元素。 如果顺序或元素重复比应用程序的性能更重要，请考虑将 List<T> 类与 Sort 该方法一起使用。

HashSet<T> 提供许多数学集运算，例如集加法（联合）和集减法。 下表列出了提供的 HashSet<T> 运算及其数学等效项。

HashSet 操作	数学等效项
UnionWith	并集或集合加法
IntersectWith	路口
ExceptWith	集合减法
SymmetricExceptWith	对称差异

除了列出的集作之外， HashSet<T> 该类还提供用于确定集相等性、重叠集以及集是另一组的子集还是超集的方法。

HashSet<T> 类实现 ISet<T> 接口。

HashSet 和 LINQ 集合运算

LINQ 提供对任何实现 Distinct 或 Union 接口的数据源的 Intersect、Except、IEnumerable 和 IQueryable 集合操作的访问。 HashSet<T> 提供更大和更强大的集合操作集。 例如， HashSet<T> 提供比较，例如 IsSubsetOf 和 IsSupersetOf。

LINQ 集作和 HashSet<T> 作之间的主要区别是 LINQ 集作始终返回新 IEnumerable<T> 集合，而 HashSet<T> 等效方法修改当前集合。

通常，如果必须创建新集，或者应用程序只需要访问提供的集作，则对任何集合或数组使用 LINQ 集作 IEnumerable<T> 将足够。 但是，如果应用程序需要访问额外的集合操作，或者不需要创建新集合，请使用HashSet<T> 类。

下表显示了 HashSet<T> 操作及其等价的 LINQ 集合操作。

HashSet 操作	LINQ 等效项
UnionWith	Union
IntersectWith	Intersect
ExceptWith	Except
未提供。	Distinct
SymmetricExceptWith	未提供。
Overlaps	未提供。
IsSubsetOf	未提供。
IsProperSubsetOf	未提供。
IsSupersetOf	未提供。
IsProperSupersetOf	未提供。
SetEquals	未提供。

另请参阅

• SortedSet<T>
• ISet<T>