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())输出：
0