vb.net 如何检查字符串数组是否为空？
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How to check if a string array is null?
提问by Maxim Petrov
I modified a workflow in TFS template, in the head of this workflow I initialized an array of string named NextChainBuildDefinition. After a few steps, I tried to check if this array is null or not.
我修改了 TFS 模板中的一个工作流，在这个工作流的头部，我初始化了一个名为NextChainBuildDefinition. 几步之后，我尝试检查这个数组是否为空。
I did this way:
我是这样做的：
String.IsNullOrEmpty(CStr(NextChainBuildDefinition.Count))
After this I see error: Exception Message: Value cannot be null.Therefore NextChainBuildDefinitionis null, and in that step it throws an exception.
在此之后，我看到错误：Exception Message: Value cannot be null.因此NextChainBuildDefinition为空，并在该步骤中引发异常。
How do I check if this string array is null?
如何检查此字符串数组是否为空？
回答by James Thorpe
You need to check if the array itself is null or empty - your current code is checking if the string conversion of the number of elements in the array is empty - this isn't going to work at all.
您需要检查数组本身是 null 还是空 - 您当前的代码正在检查数组中元素数量的字符串转换是否为空 - 这根本不起作用。
Instead, you need to do a two step check - both for if the array itself is null, and if not, if it's empty:
相反，您需要进行两步检查——检查数组本身是否为空，如果不是，则检查是否为空：
If (NextChainBuildDefinition IsNot Nothing AndAlso NextChainBuildDefinition.Count > 0) Then
'Array has contents
Else
'Array is null or empty
End if
回答by Isaac
Why not just test ubound() of the array? old question, i know.
为什么不只测试数组的 ubound() 呢？老问题，我知道。
