List<T> 构造函数
定义
重载
| List<T>() |
初始化 List<T> 类的新实例,该实例为空并且具有默认初始容量。Initializes a new instance of the List<T> class that is empty and has the default initial capacity. |
| List<T>(IEnumerable<T>) |
初始化 List<T> 类的新实例,该实例包含从指定集合复制的元素并且具有足够的容量来容纳所复制的元素。Initializes a new instance of the List<T> class that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied. |
| List<T>(Int32) |
初始化 List<T> 类的新实例,该实例为空并且具有指定的初始容量。Initializes a new instance of the List<T> class that is empty and has the specified initial capacity. |
List<T>()
public:
List();
public List ();
Public Sub New ()
示例
下面的示例演示了泛型类的无参数构造函数 List<T> 。The following example demonstrates the parameterless constructor of the List<T> generic class. 无参数构造函数将创建一个具有默认容量的列表,如显示属性所示 Capacity 。The parameterless constructor creates a list with the default capacity, as demonstrated by displaying the Capacity property.
该示例添加、插入和删除项,显示了在使用这些方法时容量如何变化。The example adds, inserts, and removes items, showing how the capacity changes as these methods are used.
using namespace System;
using namespace System::Collections::Generic;
void main()
{
List<String^>^ dinosaurs = gcnew List<String^>();
Console::WriteLine("\nCapacity: {0}", dinosaurs->Capacity);
dinosaurs->Add("Tyrannosaurus");
dinosaurs->Add("Amargasaurus");
dinosaurs->Add("Mamenchisaurus");
dinosaurs->Add("Deinonychus");
dinosaurs->Add("Compsognathus");
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\nCapacity: {0}", dinosaurs->Capacity);
Console::WriteLine("Count: {0}", dinosaurs->Count);
Console::WriteLine("\nContains(\"Deinonychus\"): {0}",
dinosaurs->Contains("Deinonychus"));
Console::WriteLine("\nInsert(2, \"Compsognathus\")");
dinosaurs->Insert(2, "Compsognathus");
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\ndinosaurs[3]: {0}", dinosaurs[3]);
Console::WriteLine("\nRemove(\"Compsognathus\")");
dinosaurs->Remove("Compsognathus");
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
dinosaurs->TrimExcess();
Console::WriteLine("\nTrimExcess()");
Console::WriteLine("Capacity: {0}", dinosaurs->Capacity);
Console::WriteLine("Count: {0}", dinosaurs->Count);
dinosaurs->Clear();
Console::WriteLine("\nClear()");
Console::WriteLine("Capacity: {0}", dinosaurs->Capacity);
Console::WriteLine("Count: {0}", dinosaurs->Count);
}
/* This code example produces the following output:
Capacity: 0
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
Capacity: 8
Count: 5
Contains("Deinonychus"): True
Insert(2, "Compsognathus")
Tyrannosaurus
Amargasaurus
Compsognathus
Mamenchisaurus
Deinonychus
Compsognathus
dinosaurs[3]: Mamenchisaurus
Remove("Compsognathus")
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
TrimExcess()
Capacity: 5
Count: 5
Clear()
Capacity: 5
Count: 0
*/
List<string> dinosaurs = new List<string>();
Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);
dinosaurs.Add("Tyrannosaurus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("Mamenchisaurus");
dinosaurs.Add("Deinonychus");
dinosaurs.Add("Compsognathus");
Console.WriteLine();
foreach(string dinosaur in dinosaurs)
{
Console.WriteLine(dinosaur);
}
Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);
Console.WriteLine("Count: {0}", dinosaurs.Count);
Console.WriteLine("\nContains(\"Deinonychus\"): {0}",
dinosaurs.Contains("Deinonychus"));
Console.WriteLine("\nInsert(2, \"Compsognathus\")");
dinosaurs.Insert(2, "Compsognathus");
Console.WriteLine();
foreach(string dinosaur in dinosaurs)
{
Console.WriteLine(dinosaur);
}
// Shows accessing the list using the Item property.
Console.WriteLine("\ndinosaurs[3]: {0}", dinosaurs[3]);
Console.WriteLine("\nRemove(\"Compsognathus\")");
dinosaurs.Remove("Compsognathus");
Console.WriteLine();
foreach(string dinosaur in dinosaurs)
{
Console.WriteLine(dinosaur);
}
dinosaurs.TrimExcess();
Console.WriteLine("\nTrimExcess()");
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);
Console.WriteLine("Count: {0}", dinosaurs.Count);
dinosaurs.Clear();
Console.WriteLine("\nClear()");
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);
Console.WriteLine("Count: {0}", dinosaurs.Count);
/* This code example produces the following output:
Capacity: 0
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
Capacity: 8
Count: 5
Contains("Deinonychus"): True
Insert(2, "Compsognathus")
Tyrannosaurus
Amargasaurus
Compsognathus
Mamenchisaurus
Deinonychus
Compsognathus
dinosaurs[3]: Mamenchisaurus
Remove("Compsognathus")
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
TrimExcess()
Capacity: 5
Count: 5
Clear()
Capacity: 5
Count: 0
*/
Imports System.Collections.Generic
Public Class Example
Public Shared Sub Main()
Dim dinosaurs As New List(Of String)
Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity)
dinosaurs.Add("Tyrannosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("Mamenchisaurus")
dinosaurs.Add("Deinonychus")
dinosaurs.Add("Compsognathus")
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity)
Console.WriteLine("Count: {0}", dinosaurs.Count)
Console.WriteLine(vbLf & "Contains(""Deinonychus""): {0}", _
dinosaurs.Contains("Deinonychus"))
Console.WriteLine(vbLf & "Insert(2, ""Compsognathus"")")
dinosaurs.Insert(2, "Compsognathus")
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
' Shows how to access the list using the Item property.
Console.WriteLine(vbLf & "dinosaurs(3): {0}", dinosaurs(3))
Console.WriteLine(vbLf & "Remove(""Compsognathus"")")
dinosaurs.Remove("Compsognathus")
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
dinosaurs.TrimExcess()
Console.WriteLine(vbLf & "TrimExcess()")
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity)
Console.WriteLine("Count: {0}", dinosaurs.Count)
dinosaurs.Clear()
Console.WriteLine(vbLf & "Clear()")
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity)
Console.WriteLine("Count: {0}", dinosaurs.Count)
End Sub
End Class
' This code example produces the following output:
'
'Capacity: 0
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'Capacity: 8
'Count: 5
'
'Contains("Deinonychus"): True
'
'Insert(2, "Compsognathus")
'
'Tyrannosaurus
'Amargasaurus
'Compsognathus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'dinosaurs(3): Mamenchisaurus
'
'Remove("Compsognathus")
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'TrimExcess()
'Capacity: 5
'Count: 5
'
'Clear()
'Capacity: 5
'Count: 0
[<EntryPoint>]
let main argv =
// We refer to System.Collections.Generic.List<'T> by its type
// abbreviation ResizeArray<'T> to avoid conflict with the List module.
// Note: In F# code, F# linked lists are usually preferred over
// ResizeArray<'T> when an extendable collection is required.
let dinosaurs = ResizeArray<_>()
// Write out the dinosaurs in the ResizeArray.
let printDinosaurs() =
printfn ""
dinosaurs |> Seq.iter (fun p -> printfn "%O" p)
printfn "\nCapacity: %i" dinosaurs.Capacity
dinosaurs.Add("Tyrannosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("Mamenchisaurus")
dinosaurs.Add("Deinonychus")
dinosaurs.Add("Compsognathus")
printDinosaurs()
printfn "\nCapacity: %i" dinosaurs.Capacity
printfn "Count: %i" dinosaurs.Count
printfn "\nContains(\"Deinonychus\"): %b" (dinosaurs.Contains("Deinonychus"))
printfn "\nInsert(2, \"Compsognathus\")"
dinosaurs.Insert(2, "Compsognathus")
printDinosaurs()
// Shows accessing the list using the Item property.
printfn "\ndinosaurs[3]: %s" dinosaurs.[3]
printfn "\nRemove(\"Compsognathus\")"
dinosaurs.Remove("Compsognathus") |> ignore
printDinosaurs()
dinosaurs.TrimExcess()
printfn "\nTrimExcess()"
printfn "Capacity: %i" dinosaurs.Capacity
printfn "Count: %i" dinosaurs.Count
dinosaurs.Clear()
printfn "\nClear()"
printfn "Capacity: %i" dinosaurs.Capacity
printfn "Count: %i" dinosaurs.Count
0 // return an integer exit code
(* This code example produces the following output:
Capacity: 0
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
Capacity: 8
Count: 5
Contains("Deinonychus"): true
Insert(2, "Compsognathus")
Tyrannosaurus
Amargasaurus
Compsognathus
Mamenchisaurus
Deinonychus
Compsognathus
dinosaurs[3]: Mamenchisaurus
Remove("Compsognathus")
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
TrimExcess()
Capacity: 5
Count: 5
Clear()
Capacity: 5
Count: 0
*)
注解
的容量 List<T> 是可容纳的元素数 List<T> 。The capacity of a List<T> is the number of elements that the List<T> can hold. 当向添加元素时 List<T> ,将根据需要通过重新分配内部数组来自动增加容量。As elements are added to a List<T>, the capacity is automatically increased as required by reallocating the internal array.
如果集合的大小可以估算,使用 List<T>(Int32) 构造函数并指定初始容量,则无需在将元素添加到时执行多个大小调整操作 List<T> 。If the size of the collection can be estimated, using the List<T>(Int32) constructor and specifying the initial capacity eliminates the need to perform a number of resizing operations while adding elements to the List<T>.
可以通过调用 TrimExcess 方法或通过显式设置属性来减少容量 Capacity 。The capacity can be decreased by calling the TrimExcess method or by setting the Capacity property explicitly. 减少容量会重新分配内存,并复制中的所有元素 List<T> 。Decreasing the capacity reallocates memory and copies all the elements in the List<T>.
此构造函数是一个 O (1) 操作。This constructor is an O(1) operation.
适用于
List<T>(IEnumerable<T>)
public:
List(System::Collections::Generic::IEnumerable<T> ^ collection);
public List (System.Collections.Generic.IEnumerable<T> collection);
new System.Collections.Generic.List<'T> : seq<'T> -> System.Collections.Generic.List<'T>
Public Sub New (collection As IEnumerable(Of T))
参数
- collection
- IEnumerable<T>
一个集合,其元素被复制到新列表中。The collection whose elements are copied to the new list.
例外
collection 为 null。collection is null.
示例
下面的示例演示了对 List<T> 范围执行操作的类的构造函数和各种方法 List<T> 。The following example demonstrates the List<T> constructor and various methods of the List<T> class that act on ranges. 创建一个字符串数组,并将其传递给构造函数,并用数组的元素填充该列表。An array of strings is created and passed to the constructor, populating the list with the elements of the array. Capacity然后显示该属性,以显示初始容量完全是保留输入元素所需的容量。The Capacity property is then displayed, to show that the initial capacity is exactly what is required to hold the input elements.
using namespace System;
using namespace System::Collections::Generic;
void main()
{
array<String^>^ input = { "Brachiosaurus",
"Amargasaurus",
"Mamenchisaurus" };
List<String^>^ dinosaurs =
gcnew List<String^>((IEnumerable<String^>^) input);
Console::WriteLine("\nCapacity: {0}", dinosaurs->Capacity);
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\nAddRange(dinosaurs)");
dinosaurs->AddRange(dinosaurs);
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\nRemoveRange(2, 2)");
dinosaurs->RemoveRange(2, 2);
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
input = gcnew array<String^> { "Tyrannosaurus",
"Deinonychus",
"Velociraptor"};
Console::WriteLine("\nInsertRange(3, (IEnumerable<String^>^) input)");
dinosaurs->InsertRange(3, (IEnumerable<String^>^) input);
Console::WriteLine();
for each(String^ dinosaur in dinosaurs )
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\noutput = dinosaurs->GetRange(2, 3)->ToArray()");
array<String^>^ output = dinosaurs->GetRange(2, 3)->ToArray();
Console::WriteLine();
for each(String^ dinosaur in output )
{
Console::WriteLine(dinosaur);
}
}
/* This code example produces the following output:
Capacity: 3
Brachiosaurus
Amargasaurus
Mamenchisaurus
AddRange(dinosaurs)
Brachiosaurus
Amargasaurus
Mamenchisaurus
Brachiosaurus
Amargasaurus
Mamenchisaurus
RemoveRange(2, 2)
Brachiosaurus
Amargasaurus
Amargasaurus
Mamenchisaurus
InsertRange(3, (IEnumerable<String^>^) input)
Brachiosaurus
Amargasaurus
Amargasaurus
Tyrannosaurus
Deinonychus
Velociraptor
Mamenchisaurus
output = dinosaurs->GetRange(2, 3)->ToArray()
Amargasaurus
Tyrannosaurus
Deinonychus
*/
using System;
using System.Collections.Generic;
public class Example
{
public static void Main()
{
string[] input = { "Brachiosaurus",
"Amargasaurus",
"Mamenchisaurus" };
List<string> dinosaurs = new List<string>(input);
Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);
Console.WriteLine();
foreach( string dinosaur in dinosaurs )
{
Console.WriteLine(dinosaur);
}
Console.WriteLine("\nAddRange(dinosaurs)");
dinosaurs.AddRange(dinosaurs);
Console.WriteLine();
foreach( string dinosaur in dinosaurs )
{
Console.WriteLine(dinosaur);
}
Console.WriteLine("\nRemoveRange(2, 2)");
dinosaurs.RemoveRange(2, 2);
Console.WriteLine();
foreach( string dinosaur in dinosaurs )
{
Console.WriteLine(dinosaur);
}
input = new string[] { "Tyrannosaurus",
"Deinonychus",
"Velociraptor"};
Console.WriteLine("\nInsertRange(3, input)");
dinosaurs.InsertRange(3, input);
Console.WriteLine();
foreach( string dinosaur in dinosaurs )
{
Console.WriteLine(dinosaur);
}
Console.WriteLine("\noutput = dinosaurs.GetRange(2, 3).ToArray()");
string[] output = dinosaurs.GetRange(2, 3).ToArray();
Console.WriteLine();
foreach( string dinosaur in output )
{
Console.WriteLine(dinosaur);
}
}
}
/* This code example produces the following output:
Capacity: 3
Brachiosaurus
Amargasaurus
Mamenchisaurus
AddRange(dinosaurs)
Brachiosaurus
Amargasaurus
Mamenchisaurus
Brachiosaurus
Amargasaurus
Mamenchisaurus
RemoveRange(2, 2)
Brachiosaurus
Amargasaurus
Amargasaurus
Mamenchisaurus
InsertRange(3, input)
Brachiosaurus
Amargasaurus
Amargasaurus
Tyrannosaurus
Deinonychus
Velociraptor
Mamenchisaurus
output = dinosaurs.GetRange(2, 3).ToArray()
Amargasaurus
Tyrannosaurus
Deinonychus
*/
Imports System.Collections.Generic
Public Class Example
Public Shared Sub Main()
Dim input() As String = { "Brachiosaurus", _
"Amargasaurus", _
"Mamenchisaurus" }
Dim dinosaurs As New List(Of String)(input)
Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity)
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & "AddRange(dinosaurs)")
dinosaurs.AddRange(dinosaurs)
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & "RemoveRange(2, 2)")
dinosaurs.RemoveRange(2, 2)
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
input = New String() { "Tyrannosaurus", _
"Deinonychus", _
"Velociraptor" }
Console.WriteLine(vbLf & "InsertRange(3, input)")
dinosaurs.InsertRange(3, input)
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & "output = dinosaurs.GetRange(2, 3).ToArray")
Dim output() As String = dinosaurs.GetRange(2, 3).ToArray()
Console.WriteLine()
For Each dinosaur As String In output
Console.WriteLine(dinosaur)
Next
End Sub
End Class
' This code example produces the following output:
'
'Capacity: 3
'
'Brachiosaurus
'Amargasaurus
'Mamenchisaurus
'
'AddRange(dinosaurs)
'
'Brachiosaurus
'Amargasaurus
'Mamenchisaurus
'Brachiosaurus
'Amargasaurus
'Mamenchisaurus
'
'RemoveRange(2, 2)
'
'Brachiosaurus
'Amargasaurus
'Amargasaurus
'Mamenchisaurus
'
'InsertRange(3, input)
'
'Brachiosaurus
'Amargasaurus
'Amargasaurus
'Tyrannosaurus
'Deinonychus
'Velociraptor
'Mamenchisaurus
'
'output = dinosaurs.GetRange(2, 3).ToArray
'
'Amargasaurus
'Tyrannosaurus
'Deinonychus
注解
按集合的枚举器读取元素的顺序将这些元素复制到 List<T> 中。The elements are copied onto the List<T> in the same order they are read by the enumerator of the collection.
此构造函数是一个 O (n) 操作,其中 n 是中的元素数目 collection 。This constructor is an O(n) operation, where n is the number of elements in collection.
另请参阅
适用于
List<T>(Int32)
public:
List(int capacity);
public List (int capacity);
new System.Collections.Generic.List<'T> : int -> System.Collections.Generic.List<'T>
Public Sub New (capacity As Integer)
参数
- capacity
- Int32
新列表最初可以存储的元素数。The number of elements that the new list can initially store.
例外
capacity 小于 0。capacity is less than 0.
示例
下面的示例演示了 List<T>(Int32) 构造函数。The following example demonstrates the List<T>(Int32) constructor. List<T>创建了容量为4的字符串的,因为已知列表的最终大小为4。A List<T> of strings with a capacity of 4 is created, because the ultimate size of the list is known to be exactly 4. 使用四个字符串填充列表,并使用方法创建只读副本 AsReadOnly 。The list is populated with four strings, and a read-only copy is created by using the AsReadOnly method.
using namespace System;
using namespace System::Collections::Generic;
void main()
{
List<String^>^ dinosaurs = gcnew List<String^>(4);
Console::WriteLine("\nCapacity: {0}", dinosaurs->Capacity);
dinosaurs->Add("Tyrannosaurus");
dinosaurs->Add("Amargasaurus");
dinosaurs->Add("Mamenchisaurus");
dinosaurs->Add("Deinonychus");
Console::WriteLine();
for each(String^ dinosaur in dinosaurs)
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\nIList<String^>^ roDinosaurs = dinosaurs->AsReadOnly()");
IList<String^>^ roDinosaurs = dinosaurs->AsReadOnly();
Console::WriteLine("\nElements in the read-only IList:");
for each(String^ dinosaur in roDinosaurs)
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\ndinosaurs[2] = \"Coelophysis\"");
dinosaurs[2] = "Coelophysis";
Console::WriteLine("\nElements in the read-only IList:");
for each(String^ dinosaur in roDinosaurs)
{
Console::WriteLine(dinosaur);
}
}
/* This code example produces the following output:
Capacity: 4
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
IList<String^>^ roDinosaurs = dinosaurs->AsReadOnly()
Elements in the read-only IList:
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
dinosaurs[2] = "Coelophysis"
Elements in the read-only IList:
Tyrannosaurus
Amargasaurus
Coelophysis
Deinonychus
*/
using System;
using System.Collections.Generic;
public class Example
{
public static void Main()
{
List<string> dinosaurs = new List<string>(4);
Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);
dinosaurs.Add("Tyrannosaurus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("Mamenchisaurus");
dinosaurs.Add("Deinonychus");
Console.WriteLine();
foreach(string s in dinosaurs)
{
Console.WriteLine(s);
}
Console.WriteLine("\nIList<string> roDinosaurs = dinosaurs.AsReadOnly()");
IList<string> roDinosaurs = dinosaurs.AsReadOnly();
Console.WriteLine("\nElements in the read-only IList:");
foreach(string dinosaur in roDinosaurs)
{
Console.WriteLine(dinosaur);
}
Console.WriteLine("\ndinosaurs[2] = \"Coelophysis\"");
dinosaurs[2] = "Coelophysis";
Console.WriteLine("\nElements in the read-only IList:");
foreach(string dinosaur in roDinosaurs)
{
Console.WriteLine(dinosaur);
}
}
}
/* This code example produces the following output:
Capacity: 4
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
IList<string> roDinosaurs = dinosaurs.AsReadOnly()
Elements in the read-only IList:
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
dinosaurs[2] = "Coelophysis"
Elements in the read-only IList:
Tyrannosaurus
Amargasaurus
Coelophysis
Deinonychus
*/
Imports System.Collections.Generic
Public Class Example
Public Shared Sub Main()
Dim dinosaurs As New List(Of String)(4)
Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity)
dinosaurs.Add("Tyrannosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("Mamenchisaurus")
dinosaurs.Add("Deinonychus")
Console.WriteLine()
For Each dinosaur As String In dinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & _
"Dim roDinosaurs As IList(Of String) = dinosaurs.AsReadOnly")
Dim roDinosaurs As IList(Of String) = dinosaurs.AsReadOnly
Console.WriteLine(vbLf & "Elements in the read-only IList:")
For Each dinosaur As String In roDinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & "dinosaurs(2) = ""Coelophysis""")
dinosaurs(2) = "Coelophysis"
Console.WriteLine(vbLf & "Elements in the read-only IList:")
For Each dinosaur As String In roDinosaurs
Console.WriteLine(dinosaur)
Next
End Sub
End Class
' This code example produces the following output:
'
'Capacity: 4
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'
'Dim roDinosaurs As IList(Of String) = dinosaurs.AsReadOnly
'
'Elements in the read-only IList:
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'
'dinosaurs(2) = "Coelophysis"
'
'Elements in the read-only IList:
'Tyrannosaurus
'Amargasaurus
'Coelophysis
'Deinonychus
注解
的容量 List<T> 是可容纳的元素数 List<T> 。The capacity of a List<T> is the number of elements that the List<T> can hold. 当向添加元素时 List<T> ,将根据需要通过重新分配内部数组来自动增加容量。As elements are added to a List<T>, the capacity is automatically increased as required by reallocating the internal array.
如果集合的大小可为估算值,则指定初始容量后,无需在将元素添加到时执行多个大小调整操作 List<T> 。If the size of the collection can be estimated, specifying the initial capacity eliminates the need to perform a number of resizing operations while adding elements to the List<T>.
可以通过调用 TrimExcess 方法或通过显式设置属性来减少容量 Capacity 。The capacity can be decreased by calling the TrimExcess method or by setting the Capacity property explicitly. 减少容量会重新分配内存,并复制中的所有元素 List<T> 。Decreasing the capacity reallocates memory and copies all the elements in the List<T>.
此构造函数是一个 O (1) 操作。This constructor is an O(1) operation.