循环遍历 vb.net 中的通用列表
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Loop through Generic List in vb.net
提问by acadia
In my VB.net application I am populating my customer object and looping through it as shown below.
在我的 VB.net 应用程序中，我正在填充我的客户对象并循环遍历它，如下所示。
As there are thousands of customers, I want to do it 500 customers at a time.
由于有成千上万的客户，我想一次做 500 个客户。
Is there anyway I can have one more For loop to process 500 customers at one shot in vB.net
无论如何，我是否可以再使用一个 For 循环来在 vB.net 中一次性处理 500 个客户
I am not using LinQ as the database is Oracle.
我没有使用 LinQ，因为数据库是 Oracle。
is there anything like
有什么像
Thanks
谢谢
Dim customerList as new List(of customer)
Dim Customer as new Customer
Try
CustomerList=dataAccess.GetAllCustomers()
if not CustomerList is nothing then
For each Customer in CustomerList
BuildXML(custmer.Name,Customer.age,Customer.city)
next
ProcessXMLWS(strxml)
end if
Catch ex as exception
LogError(ex.message)
End try
回答by SLaks
You can loop through blocks of 500 Customerobjects like this:
您可以Customer像这样循环遍历 500 个对象的块：
For i As Integer = 0 To CustomerList.Count Step 500
'Do things
Next
However, it won't do you any good.
Your code is using each Customerobject individually, so there is nothing you can do with 500 at a time.
然而，这对你没有任何好处。您的代码Customer单独使用每个对象，因此一次使用 500 个对象无能为力。
EDIT:
编辑：
If you mean that you only want to process the first 500 Customerobjects, try this:
如果您的意思是只想处理前 500 个Customer对象，请尝试以下操作：
For i As Integer = 0 To Math.Min(500, CustomerList.Count)
Set Customer = CustomerList(i)
BuildXML(custmer.Name, Customer.age, Customer.city)
Next
As an aside, you shouldn't write Dim Customer As New Customer- by adding the Newkeyword, you create an extra Customerinstance that you never use. Instead, write Dim Customer As Customerto declare the variable without creating a new Customerinstance.
顺便说一句，您不应该编写Dim Customer As New Customer- 通过添加New关键字，您会创建一个Customer您从未使用过的额外实例。相反，写入Dim Customer As Customer声明变量而不创建新Customer实例。
Also, you can use VB's IsNotkeyword in the If statement, like this:
此外，您可以IsNot在 If 语句中使用 VB 的关键字，如下所示：
If CustomerList IsNot Nothing Then
回答by adatapost
Use counter variable.
使用计数器变量。
Dim counter as Integer = 1
For each Customer in CustomerList
If counter = 500 Then
ProcessXMLWS(strxml)
strxml="" '//Empty if any.'
counter = 1
Next
BuildXML(custmer.Name, Customer.age, Customer.city)
counter += 1
next
