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VB.Net program to demonstrate the ToLookup() LINQ extension method

By Nidhi Last Updated : November 14, 2024

VB.Net – ToLookup() LINQ Extension Method

In this program, we will use ToLookup() extension method to group data. It is similar to the GroupBy() method but the only difference is GroupBy execution is deferred, whereas ToLookup execution is immediate.

Program/Source Code:

The source code to demonstrate the ToLookup() LINQ extension method is given below. The given program is compiled and executed successfully.

VB.Net code to demonstrate the example of ToLookup() LINQ extension method

'VB.NET program to demonstrate the 
'ToLookup() LINQ extension method.

Imports System
Imports System.IO
Imports System.Linq

Module Module1
    Public Class Employee
        Public id As Integer
        Public name As String
        Public age As Integer
    End Class

    Sub Main()
        Dim empList = New List(Of Employee) From
        {
            New Employee() With {.id = 101, .name = "Amit", .age = 21},
            New Employee() With {.id = 102, .name = "Arun", .age = 22},
            New Employee() With {.id = 103, .name = "Aman", .age = 23},
            New Employee() With {.id = 104, .name = "Amar", .age = 21},
            New Employee() With {.id = 105, .name = "Akki", .age = 22},
            New Employee() With {.id = 105, .name = "Anuj", .age = 23}
        }

        Dim Emps = empList.ToLookup(Function(e) e.age)

        For Each emp In Emps
            Console.WriteLine("Age Group: {0}", emp.Key)

            For Each e In emp.AsEnumerable()
                Console.WriteLine(vbTab & "Employee Name: {0}", e.name)
            Next
        Next
    End Sub
End Module

Output

Age Group: 21
        Employee Name: Amit
        Employee Name: Amar
Age Group: 22
        Employee Name: Arun
        Employee Name: Akki
Age Group: 23
        Employee Name: Aman
        Employee Name: Anuj
Press any key to continue . . .

Explanation

In the above program, we created a module Module1 that contains a class Employee and the Main() function. The Main() function is the entry point for the program.

The Employee class contains data member "id", "name" and "age". In the Main() function, We created the list of employees. Here, we used ToLookup() LINQ extension method to group employee records based on their age and then print those employee records on the console screen.

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