我想在VB.NET控制台应用程序中创建指定数量的字符串。我尝试过这段代码,但它抛出异常:
NullReferenceException:Object Reference未设置为Object的实例。
这是代码:
Module RandStrConsole
Dim r As New Random
Dim s As String
Dim result As System.Text.StringBuilder
Dim sb As System.Text.StringBuilder
Dim MaxChar As Integer
Sub Main()
Console.Write("Enter String: ") : s = Console.ReadLine
Console.Write("Maxchar: ") : MaxChar = Console.ReadLine
For i As Integer = 1 To MaxChar
Dim idx As Integer = r.Next(0, s.Count - 1)
result = sb.Append(s.Substring(idx, 1)) 'NullReferenceException: Object Reference not set into an instance of an Object.
result.ToString()
Next
Console.WriteLine(result)
Console.ReadKey()
End Sub
End Module
评论部分指出发生异常的位置。
答案 0 :(得分:-1)
您忘记初始化StringBuilders
。您必须使用New
keyword。
Dim result As New System.Text.StringBuilder
Dim sb As New System.Text.StringBuilder