Merge multiple list of string to list of object using VB.NET - vb.net

Question

I have 3 list of strings.
List1 - Student Name List2 - Student School List3 - Student Location
Student 1 Student 1 School Student 1 Location
Student 2 Student 2 School Student 2 Location
Student 3 Student 3 School Student 3 Location
Student 4 Student 4 School Student 4 Location
Student 5 Student 5 School Student 5 Location
And a structure StudentDetails
Public Structure StudentDetails()
Public StudentName As String
Public StudentSchool As String
Public StudentLocation As String
End Structure
I want to make the first 3 list to List of StudentDetails
I have used the following code to do this
Dim StudentDetailsList As New List(Of StudentDetails)
For i = 0 to List1.Count - 1
Dim StudentDetail As New StudentDetail
With StudentDetail
.StudentName = List1(i)
.StudentSchool = List2(i)
.StudentLocation = List3(i)
End With
StudentDetailsList.Add(StudentDetail)
Next
Is there a better way to do this using Linq or some other method?

Answer 1

There are many ways to do that, some easier to read than others.
First, I would make StudentDetails a class instead of a structure (see, e.g., When should I use a struct instead of a class?.
Now that you have a class, you can give it a New constructor with parameters, as used in the third example here:
Option Infer On
Option Strict On
Module Module1
Public Class StudentDetails
Public Name As String
Public School As String
Public Location As String
Public Sub New()
' empty constuctor
End Sub
Public Sub New(name As String, school As String, location As String)
Me.Name = name
Me.School = school
Me.Location = location
End Sub
' make it easy to represent StudentDetails as a string...
Public Overrides Function ToString() As String
Return $"{Me.Name} {Me.School} {Me.Location}"
End Function
End Class
Sub Main()
Dim list1 As New List(Of String) From {"Adam", "Betty", "Charles", "Wilma"}
Dim list2 As New List(Of String) From {"Ace", "Best", "Classy", "Wacky"}
Dim list3 As New List(Of String) From {"Attic", "Basement", "Cellar", "Windowledge"}
' a not-very tidy example using Zip:
Dim StudentDetailsList = list1.Zip(list2, Function(a, b) New With {.name = a, .school = b}).Zip(list3, Function(c, d) New StudentDetails With {.Name = c.name, .School = c.school, .Location = d}).ToList()
' one way of writing out the StudentDetailsList...
For Each s In StudentDetailsList
Console.WriteLine(s.ToString())
Next
StudentDetailsList.Clear()
' a bit cleaner using a loop:
For i = 0 To list1.Count() - 1
StudentDetailsList.Add(New StudentDetails With {
.Name = list1(i),
.School = list2(i),
.Location = list3(i)})
Next
' another way of writing out the StudentDetailsList...
Console.WriteLine(String.Join(vbCrLf, StudentDetailsList))
StudentDetailsList.Clear()
' easy to write with a New constructor, but not necessarily as easy to read as the previous example:
For i = 0 To list1.Count() - 1
StudentDetailsList.Add(New StudentDetails(list1(i), list2(i), list3(i)))
Next
Console.WriteLine(String.Join(vbCrLf, StudentDetailsList))
Console.ReadLine()
End Sub
End Module
I used the $ string formatter in the .ToString() method: it was introduced with VS2015, so if you are using an earlier version you can use String.Format("{0} {1} {2}", Me.Name, Me.School, Me.Location) instead.
As a note on naming the properties of StudentDetails, the "Student" in StudentName, StudentSchool and StudentLocation is redundant.

Answer 2

Well, you can use an overload of Select extension method to projects each element of one of the list into a new StudentDetail by incorporating the element's index. Assuming the three lists have the same amount of elements, you can do the following:
// using C#
var result=List1.Select((e,i))=>new StudentDetail
{
StudentName =e,
StudentSchool = List2[i],
StudentLocation = List3[i]
}).ToList();
I think in Vb would be (sorry, I'm a c# programmer):
Dim StudentDetailsList=List1.Select(Function(e, i) _
New StudentDetail
With StudentDetail
.StudentName = e
.StudentSchool = List2(i)
.StudentLocation = List3(i)
End With).ToList();
But using a for is not a bad solution, in many cases is more readable.