StringBuilder instances that never build a string clutter the code and worse are a drag on performance. Either they
should be removed, or the missing ToString() call should be added.
Noncompliant code example
Public Sub DoSomething(ByVal strings As List(Of String))
Dim sb As StringBuilder = New StringBuilder() ' Noncompliant
sb.Append("Got: ")
For Each str As String In strings
sb.Append(str).Append(", ")
Next
End Sub
Compliant solution
Public Sub DoSomething(ByVal strings As List(Of String))
For Each str As String In strings
Next
End Sub
or
Public Sub DoSomething(ByVal strings As List(Of String))
Dim sb As StringBuilder = New StringBuilder()
sb.Append("Got: ")
For Each str As String In strings
sb.Append(str).Append(", ")
Next
My.Application.Log.WriteEntry(sb.ToString())
End Sub
Exceptions
No issue is reported when StringBuilder is:
- Accessed through
sb.CopyTo(), sb.GetChunks(), sb.Length, or sb(index).
- Passed as a method argument, on the grounds that it will likely be accessed through a
ToString() invocation there.
- Passed in as a parameter to the current method, on the grounds that the callee will materialize the string.
- Retrieved by a custom function (
Dim sb As StringBuilder = GetStringBuilder()).
- Returned by the method.
