Array.AsReadOnly<T>(T[]) Methode
Definitie
Belangrijk
Bepaalde informatie heeft betrekking op een voorlopige productversie die aanzienlijk kan worden gewijzigd voordat deze wordt uitgebracht. Microsoft biedt geen enkele expliciete of impliciete garanties met betrekking tot de informatie die hier wordt verstrekt.
Retourneert een alleen-lezen wrapper voor de opgegeven matrix.
public:
generic <typename T>
static System::Collections::ObjectModel::ReadOnlyCollection<T> ^ AsReadOnly(cli::array <T> ^ array);public static System.Collections.ObjectModel.ReadOnlyCollection<T> AsReadOnly<T>(T[] array);static member AsReadOnly : 'T[] -> System.Collections.ObjectModel.ReadOnlyCollection<'T>Public Shared Function AsReadOnly(Of T) (array As T()) As ReadOnlyCollection(Of T)Type parameters
- T
Het type van de elementen van de matrix.
Parameters
- array
- T[]
De eendimensionale matrix op basis van nul om te verpakken in een alleen-lezen ReadOnlyCollection<T> wrapper.
Retouren
Een alleen-lezen ReadOnlyCollection<T> wrapper voor de opgegeven matrix.
Uitzonderingen
array is null.
Voorbeelden
In het volgende voorbeeld wordt een matrix verpakt in een alleen-lezen ReadOnlyCollection<T>matrix.
using System;
using System.Collections.Generic;
public class SamplesArray {
public static void Main() {
// Create and initialize a new string array.
String[] myArr = { "The", "quick", "brown", "fox" };
// Display the values of the array.
Console.WriteLine( "The string array initially contains the following values:" );
PrintIndexAndValues( myArr );
// Create a read-only IList wrapper around the array.
IList<string> myList = Array.AsReadOnly( myArr );
// Display the values of the read-only IList.
Console.WriteLine( "The read-only IList contains the following values:" );
PrintIndexAndValues( myList );
// Attempt to change a value through the wrapper.
try {
myList[3] = "CAT";
}
catch ( NotSupportedException e ) {
Console.WriteLine( "{0} - {1}", e.GetType(), e.Message );
Console.WriteLine();
}
// Change a value in the original array.
myArr[2] = "RED";
// Display the values of the array.
Console.WriteLine( "After changing the third element, the string array contains the following values:" );
PrintIndexAndValues( myArr );
// Display the values of the read-only IList.
Console.WriteLine( "After changing the third element, the read-only IList contains the following values:" );
PrintIndexAndValues( myList );
}
public static void PrintIndexAndValues( String[] myArr ) {
for ( int i = 0; i < myArr.Length; i++ ) {
Console.WriteLine( " [{0}] : {1}", i, myArr[i] );
}
Console.WriteLine();
}
public static void PrintIndexAndValues( IList<string> myList ) {
for ( int i = 0; i < myList.Count; i++ ) {
Console.WriteLine( " [{0}] : {1}", i, myList[i] );
}
Console.WriteLine();
}
}
/*
This code produces the following output.
The string array initially contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
The read-only IList contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
System.NotSupportedException - Collection is read-only.
After changing the third element, the string array contains the following values:
[0] : The
[1] : quick
[2] : RED
[3] : fox
After changing the third element, the read-only IList contains the following values:
[0] : The
[1] : quick
[2] : RED
[3] : fox
*/
open System
open System.Collections.Generic
let printIndexAndValues (myList: IList<'a>) =
for i = 0 to myList.Count - 1 do
printfn $" [{i}] : {myList[i]}"
printfn ""
// Create and initialize a new string array.
let myArr = [| "The"; "quick"; "brown"; "fox" |]
// Display the values of the array.
printfn "The string array initially contains the following values:"
printIndexAndValues myArr
// Create a read-only IList wrapper around the array.
let myList: IList<_> = Array.AsReadOnly myArr
// Display the values of the read-only IList.
printfn "The read-only IList contains the following values:"
printIndexAndValues myList
// Attempt to change a value through the wrapper.
try
myList[3] <- "CAT"
with :? NotSupportedException as e ->
printfn $"{e.GetType()} - {e.Message}\n"
// Change a value in the original array.
myArr[2] <- "RED"
// Display the values of the array.
printfn "After changing the third element, the string array contains the following values:"
printIndexAndValues myArr
// Display the values of the read-only IList.
printfn "After changing the third element, the read-only IList contains the following values:"
printIndexAndValues myList
// This code produces the following output.
// The string array initially contains the following values:
// [0] : The
// [1] : quick
// [2] : brown
// [3] : fox
//
// The read-only IList contains the following values:
// [0] : The
// [1] : quick
// [2] : brown
// [3] : fox
//
// System.NotSupportedException - Collection is read-only.
//
// After changing the third element, the string array contains the following values:
// [0] : The
// [1] : quick
// [2] : RED
// [3] : fox
//
// After changing the third element, the read-only IList contains the following values:
// [0] : The
// [1] : quick
// [2] : RED
// [3] : fox
Imports System.Collections.Generic
Public Class SamplesArray
Public Shared Sub Main()
' Create and initialize a new string array.
Dim myArr As String() = {"The", "quick", "brown", "fox"}
' Display the values of the array.
Console.WriteLine("The string array initially contains the following values:")
PrintIndexAndValues(myArr)
' Create a read-only IList wrapper around the array.
Dim myList As IList(Of String) = Array.AsReadOnly(myArr) '
' Display the values of the read-only IList.
Console.WriteLine("The read-only IList contains the following values:")
PrintIndexAndValues(myList)
' Attempt to change a value through the wrapper.
Try
myList(3) = "CAT"
Catch e As NotSupportedException
Console.WriteLine("{0} - {1}", e.GetType(), e.Message)
Console.WriteLine()
End Try
' Change a value in the original array.
myArr(2) = "RED"
' Display the values of the array.
Console.WriteLine("After changing the third element, the string array contains the following values:")
PrintIndexAndValues(myArr)
' Display the values of the read-only IList.
Console.WriteLine("After changing the third element, the read-only IList contains the following values:")
PrintIndexAndValues(myList)
End Sub
Overloads Public Shared Sub PrintIndexAndValues(myArr() As String)
Dim i As Integer
For i = 0 To myArr.Length - 1
Console.WriteLine(" [{0}] : {1}", i, myArr(i))
Next i
Console.WriteLine()
End Sub
Overloads Public Shared Sub PrintIndexAndValues(myList As IList(Of String))
Dim i As Integer
For i = 0 To myList.Count - 1
Console.WriteLine(" [{0}] : {1}", i, myList(i))
Next i
Console.WriteLine()
End Sub
End Class
'This code produces the following output.
'
'The string array initially contains the following values:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
'
'The read-only IList contains the following values:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
'
'System.NotSupportedException - Collection is read-only.
'
'After changing the third element, the string array contains the following values:
' [0] : The
' [1] : quick
' [2] : RED
' [3] : fox
'
'After changing the third element, the read-only IList contains the following values:
' [0] : The
' [1] : quick
' [2] : RED
' [3] : fox
Opmerkingen
Als u wijzigingen in de matrix wilt voorkomen, maakt u de matrix alleen beschikbaar via deze wrapper.
Een verzameling die alleen-lezen is, is gewoon een verzameling met een wrapper die voorkomt dat de verzameling wordt gewijzigd; Als er daarom wijzigingen worden aangebracht in de onderliggende verzameling, weerspiegelt de verzameling alleen-lezen deze wijzigingen.
Deze methode is een O(1)-bewerking.