`Enum.Parse`

Sometimes a String must be converted into an Enum. This requires a special Function call. In VB.NET we use the Enum.Parse, or TryParse, Functions.

We handle exceptions and errors for each method. Often TryParse is a better choice if our data is not already validated.

First example

This example introduces an Enum of name PetType. In the Main Sub, we have a String literal with value "Dog". We call [Enum].Parse to get its same-named Enum.

Info The GetType Function is used with the argument VehicleType. This is the Type argument to the Enum.Parse Function.

Important The Enum type uses a special syntax where it is surrounded by square brackets. This indicates a Type, not the Enum keyword.

Module Module1

    ''' <summary>
    ''' Types of pets.
    ''' </summary>
    Enum PetType
        None
        Cat
        Dog
    End Enum

    Sub Main()

        ' Convert String to Enum.
        Dim value As String = "Dog"
        Dim type As PetType = [Enum].Parse(GetType(PetType), value)

        ' Test Enum.
        If type = PetType.Dog Then
            Console.WriteLine("Equals dog")
        End If

    End Sub

End Module
Equals dog

Example 2

Next, we learn that Enum.Parse will throw an Exception on an invalid String. One way to handle this problem is to use a Try-Catch block to capture possible errors.

Module Module1

    Enum VehicleType
        None
        Truck
        Sedan
        Coupe
    End Enum

    Sub Main()

        ' An invalid String.
        Dim value As String = "Spaceship"

        Try
            ' Parse the invalid String.
            Dim type As VehicleType = [Enum].Parse(GetType(VehicleType), value)
        Catch ex As Exception
            ' Write the Exception.
            Console.WriteLine(ex)
        End Try

    End Sub

End ModuleSystem.ArgumentException: Requested value 'Spaceship' was not found.
   at System.Enum.EnumResult.SetFailure...

`TryParse`

Next, the TryParse Function is available. It handles errors in a safer, faster way. It does not throw an Exception on an invalid String that cannot be converted.

Return Enum.TryParse returns False if the string cannot be converted. The Enum is set to the default value.

Module Module1

    Enum VehicleType
        None
        Truck
        Sedan
    End Enum

    Sub Main()

        ' An invalid String.
        Dim value As String = "Starship"

        ' Parse the invalid String.
        Dim result As VehicleType
        [Enum].TryParse(value, result)

        ' It is the default.
        Console.WriteLine(result.ToString())
    End Sub

End Module
None

We require no custom conversion methods to parse Enums in VB.NET programs. Instead, the Enum.Parse and TryParse Functions fill this need.

Final notes

If an invalid String may be encountered, the TryParse Function is often superior. Avoiding exceptions is faster in most programs.