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.

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 Module
Value 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.

Many VB.NET programs will require the String List, and using this construct, as well as the List generic with other types, is essential.