VB.NET Enumerable.DefaultIfEmpty方法代码示例

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本文整理汇总了VB.NET中System.Linq.Enumerable.DefaultIfEmpty方法的典型用法代码示例。如果您正苦于以下问题：VB.NET Enumerable.DefaultIfEmpty方法的具体用法？VB.NET Enumerable.DefaultIfEmpty怎么用？VB.NET Enumerable.DefaultIfEmpty使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。

在下文中一共展示了Enumerable.DefaultIfEmpty方法的3个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于我们的系统推荐出更棒的VB.NET代码示例。

示例1: DefaultIfEmptyEx2

Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Sub DefaultIfEmptyEx2()
    ' Create a Pet object to use as the default value.
    Dim defaultPet As New Pet With {.Name = "Default Pet", .Age = 0}

    ' Create a List of Pet objects.
    Dim pets1 As New List(Of Pet)(New Pet() _
                          {New Pet With {.Name = "Barley", .Age = 8},
                           New Pet With {.Name = "Boots", .Age = 4},
                           New Pet With {.Name = "Whiskers", .Age = 1}})

    Dim output1 As New System.Text.StringBuilder
    ' Enumerate the items in the list, calling DefaultIfEmpty() 
    ' with a default value.
    For Each pet As Pet In pets1.DefaultIfEmpty(defaultPet)
        output1.AppendLine("Name: " & pet.Name)
    Next

    ' Display the output.
    Console.WriteLine(output1.ToString())

    ' Create an empty List.
    Dim pets2 As New List(Of Pet)

    Dim output2 As New System.Text.StringBuilder
    ' Enumerate the items in the list, calling DefaultIfEmpty() 
    ' with a default value.
    For Each pet As Pet In pets2.DefaultIfEmpty(defaultPet)
        output2.AppendLine("Name: " & pet.Name)
    Next

    ' Display the output.
    Console.WriteLine(output2.ToString())
End Sub

开发者ID:VB.NET开发者，项目名称:System.Linq，代码行数:38，代码来源:Enumerable.DefaultIfEmpty

输出：

Name: Barley
Name: Boots
Name: Whiskers

Name: Default Pet

示例2: DefaultIfEmptyEx1

Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Sub DefaultIfEmptyEx1()
    ' Create a List of Pet objects.
    Dim pets As New List(Of Pet)(New Pet() _
                         {New Pet With {.Name = "Barley", .Age = 8},
                          New Pet With {.Name = "Boots", .Age = 4},
                          New Pet With {.Name = "Whiskers", .Age = 1}})

    Dim output As New System.Text.StringBuilder
    ' Iterate through the items in the List, calling DefaultIfEmpty().
    For Each pet As Pet In pets.DefaultIfEmpty()
        output.AppendLine(pet.Name)
    Next

    ' Display the output.
    Console.WriteLine(output.ToString())
End Sub

开发者ID:VB.NET开发者，项目名称:System.Linq，代码行数:21，代码来源:Enumerable.DefaultIfEmpty

输出：

Barley
Boots
Whiskers

示例3: List

' Create an empty List.
Dim numbers As New List(Of Integer)()

Dim output As New System.Text.StringBuilder
' Iterate through the items in the List, calling DefaultIfEmpty().
For Each number As Integer In numbers.DefaultIfEmpty()
    output.AppendLine(number)
Next

' Display the output.
Console.WriteLine(output.ToString())

开发者ID:VB.NET开发者，项目名称:System.Linq，代码行数:11，代码来源:Enumerable.DefaultIfEmpty

输出：

注：本文中的System.Linq.Enumerable.DefaultIfEmpty方法示例整理自Github/MSDocs等源码及文档管理平台，相关代码片段筛选自各路编程大神贡献的开源项目，源码版权归原作者所有，传播和使用请参考对应项目的License；未经允许，请勿转载。