TextInfo.ReadOnly(TextInfo) 方法

定义

命名空间:

System.Globalization

程序集:

System.Runtime.dll

Source:

TextInfo.cs

返回指定的 TextInfo 对象的只读版本。

public:
 static System::Globalization::TextInfo ^ ReadOnly(System::Globalization::TextInfo ^ textInfo);

public static System.Globalization.TextInfo ReadOnly (System.Globalization.TextInfo textInfo);

static member ReadOnly : System.Globalization.TextInfo -> System.Globalization.TextInfo

Public Shared Function ReadOnly (textInfo As TextInfo) As TextInfo

参数

textInfo

TextInfo

TextInfo 对象。

返回

TextInfo

如果 textInfo 是只读的，则为由 textInfo 参数指定的 TextInfo 对象。

- 或 -

如果 textInfo 不是只读的，则为由 textInfo 指定的 TextInfo 对象的只读成员副本。

例外

ArgumentNullException

textInfo 为 null。

示例

下面的代码示例演示 和 CloneReadOnly 方法。

// This example demonstrates the TextInfo.Clone() and
// TextInfo.ReadOnly() methods.

using System;
using System.Globalization;

class Sample
{
    public static void Main()
    {
// Get the TextInfo of a predefined culture that ships with
// the .NET Framework.
    CultureInfo ci = new CultureInfo("en-US");
    TextInfo ti1 = ci.TextInfo;

// Display whether the TextInfo is read-only or not.
    DisplayReadOnly("1) The original TextInfo object", ti1);
    Console.WriteLine();

// Create a clone of the original TextInfo and cast the clone to a TextInfo type.
    Console.WriteLine("2a) Create a clone of the original TextInfo object...");
    TextInfo ti2 = (TextInfo)ti1.Clone();

// Display whether the clone is read-only.
    DisplayReadOnly("2b) The TextInfo clone", ti2);

// Set the ListSeparator property on the TextInfo clone.
    Console.WriteLine("2c) The original value of the clone's ListSeparator " +
                      "property is \"{0}\".", ti2.ListSeparator);
    ti2.ListSeparator = "/";
    Console.WriteLine("2d) The new value of the clone's ListSeparator " +
                      "property is \"{0}\".\n", ti2.ListSeparator);

// Create a read-only clone of the original TextInfo.
    Console.WriteLine("3a) Create a read-only clone of the original TextInfo object...");
    TextInfo ti3 = TextInfo.ReadOnly(ti1);

// Display whether the read-only clone is actually read-only.
    DisplayReadOnly("3b) The TextInfo clone", ti3);

// Try to set the ListSeparator property of a read-only TextInfo object. Use the
// IsReadOnly property again to determine whether to attempt the set operation. You
// could use a try-catch block instead and catch an InvalidOperationException when
// the set operation fails, but that programming technique is inefficient.
    Console.WriteLine("3c) Try to set the read-only clone's LineSeparator " +
                      "property.");
    if (ti3.IsReadOnly == true)
        {
        Console.WriteLine("3d) The set operation is invalid.");
        }
    else
        {
        // This clause is not executed.
        ti3.ListSeparator = "/";
        Console.WriteLine("3d) The new value of the clone's ListSeparator " +
                          "property is \"{0}\".\n", ti2.ListSeparator);
        }
    }

    private static void DisplayReadOnly(string caption, TextInfo ti)
    {
    Console.WriteLine("{0} is {1}read-only.",
                      caption, ti.IsReadOnly ? "" : "not ");
    }
}

/*
This code example produces the following results:

1) The original TextInfo object is not read-only.

2a) Create a clone of the original TextInfo object...
2b) The TextInfo clone is not read-only.
2c) The original value of the clone's ListSeparator property is ",".
2d) The new value of the clone's ListSeparator property is "/".

3a) Create a read-only clone of the original TextInfo object...
3b) The TextInfo clone is read-only.
3c) Try to set the read-only clone's LineSeparator property.
3d) The set operation is invalid.

*/

' This example demonstrates the TextInfo.Clone() and
' TextInfo.ReadOnly() methods.

Imports System.Globalization

Class Sample
    Public Shared Sub Main() 
        ' Get the TextInfo of a predefined culture that ships with 
        ' the .NET Framework.
        Dim ci As New CultureInfo("en-US")
        Dim ti1 As TextInfo = ci.TextInfo
        
        ' Display whether the TextInfo is read-only or not.
        DisplayReadOnly("1) The original TextInfo object", ti1)
        Console.WriteLine()
        
        ' Create a clone of the original TextInfo and cast the clone to a TextInfo type.
        Console.WriteLine("2a) Create a clone of the original TextInfo object...")
        Dim ti2 As TextInfo = CType(ti1.Clone(), TextInfo)
        
        ' Display whether the clone is read-only.
        DisplayReadOnly("2b) The TextInfo clone", ti2)
        
        ' Set the ListSeparator property on the TextInfo clone.
        Console.WriteLine("2c) The original value of the clone's ListSeparator " & _
                          "property is ""{0}"".", ti2.ListSeparator)
        ti2.ListSeparator = "/"
        Console.WriteLine("2d) The new value of the clone's ListSeparator " & _ 
                          "property is ""{0}""." & vbCrLf, ti2.ListSeparator)
        
        ' Create a read-only clone of the original TextInfo.
        Console.WriteLine("3a) Create a read-only clone of the original TextInfo object...")
        Dim ti3 As TextInfo = TextInfo.ReadOnly(ti1)
        
        ' Display whether the read-only clone is actually read-only.
        DisplayReadOnly("3b) The TextInfo clone", ti3)
        
        ' Try to set the ListSeparator property of a read-only TextInfo object. Use the
        ' IsReadOnly property again to determine whether to attempt the set operation. You 
        ' could use a try-catch block instead and catch an InvalidOperationException when
        ' the set operation fails, but that programming technique is inefficient.
        Console.WriteLine("3c) Try to set the read-only clone's LineSeparator property.")
        If ti3.IsReadOnly = True Then
            Console.WriteLine("3d) The set operation is invalid.")
        Else
            ' This clause is not executed.
            ti3.ListSeparator = "/"
            Console.WriteLine("3d) The new value of the clone's ListSeparator " & _ 
                              "property is ""{0}""." & vbCrLf, ti2.ListSeparator)
        End If
    
    End Sub
    
    Private Shared Sub DisplayReadOnly(ByVal caption As String, ByVal ti As TextInfo)
        Dim middle As String
        If ti.IsReadOnly = True Then
            middle = ""
        Else 
            middle = "not "
        End If        
        Console.WriteLine("{0} is {1}read-only.", caption, middle)
    End Sub
End Class

'
'This code example produces the following results:
'
'1) The original TextInfo object is not read-only.
'
'2a) Create a clone of the original TextInfo object...
'2b) The TextInfo clone is not read-only.
'2c) The original value of the clone's ListSeparator property is ",".
'2d) The new value of the clone's ListSeparator property is "/".
'
'3a) Create a read-only clone of the original TextInfo object...
'3b) The TextInfo clone is read-only.
'3c) Try to set the read-only clone's LineSeparator property.
'3d) The set operation is invalid.
'

另请参阅

• MemberwiseClone()