String List. Often in VB.NET programs we want to store multiple Strings together. These can be string literals, or dynamically-created strings. We can do this with a String List.
By creating a special kind of List, we can store and access just Strings. The List is a generic type, so we specify its type with the keywords "Of String."
Example. In VB.NET programs we usually need to place Strings onto a List with the Add() function. We can do this at any point in the program.
Step 1 We create our String List with the "Of String" keywords on the type. We call Add() 3 times.
Step 2 We create a string dynamically by calling ToString() on an Integer. This string can also be placed into the String List.
Step 3 We use For to iterate over the indexes in the String List. Note we must subtract 1 from the Count to stay in range.
Step 4 It is usually better to use For Each loops if we just want to access each element in a List.
Module Module1
Sub Main()
' Step 1: create new List and Add 3 strings to it.
Dim values = New List(Of String)
values.Add("one")
values.Add("two")
values.Add("THREE")
' Step 2: we can add strings that are not literals.
Dim test = 100.ToString()
values.Add(test)
' Step 3: use For to iterate over indexes of string list.
For i = 0 to values.Count - 1
' Get element.
Dim value = values(i)
' Display with string interpolation syntax.
Console.WriteLine($"Value {i}: {value}")
Next
' Step 4: use For Each to access elements in string list more safely.
For Each value in values
If char.IsUpper(value(0))
Console.WriteLine($"Uppercase: {value}")
End If
Next
End Sub
End ModuleValue 0: one
Value 1: two
Value 2: THREE
Value 3: 100
Uppercase: THREE
String List optimizations. In older VB.NET programs, we needed to cast values from an ArrayList, but the List type does not require casting. Each String is returned ready-to-use.
And This leads to both clearer code, and faster code, as no overhead from handling Objects is needed.
Summary. Many VB.NET programs will require the String List, and using this construct, as well as the List generic with other types, is essential.
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