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VB.NET COLLECTIONS

Collections is a type used to store more than one element of different types.
Different Collections are used to store elements and retreive elements in different styles.

VB.NET STACK Collection

Stack is used to store multiple values irrespective of datatypes.
It follows lifo(last in first out).
Push method is used to insert values into stack and pop is used to delete values from stack.

VB.NET stack example program

Module Module1

    Sub Main()
        'Create object for Stack
        Dim sta As New Stack(Of Integer)
        'Push()
        sta.Push(1)
        sta.Push(2)
        sta.Push(3)
        sta.Push(4)
        sta.Push(5)
        'Print
        For Each i As Integer In sta
            Console.WriteLine(i)
        Next
        'Count
        Console.WriteLine("No.of elements in stack " & sta.Count)
        'Pop()
        Console.WriteLine("Pop element is " & sta.Pop())
        'Print
        For Each i As Integer In sta
            Console.WriteLine(i)
        Next
        'Peek
        Console.WriteLine("Peek element is " & sta.Peek())
        'Print
        For Each i As Integer In sta
            Console.WriteLine(i)
        Next
        'Count
        Console.WriteLine("No.of elements in stack " & sta.Count)
        'Clear
        sta.Clear()
        'Count
        Console.WriteLine("No.of elements in stack " & sta.Count)
        Console.ReadLine()
    End Sub

End Module

Output

5
4
3
2
1
No.of elements in stack 5
Pop element is 5
4
3
2

1 Peek element is 4
4
3
2
1
No.of elements in stack 4
No.of elements in stack 0

Explanation

Push method is used to add elements to Stack.
Pop method is used to remove elements from Stack.
Peek method is used to retreive the topmost element in Stack.
Count method is used to retreive the no. of elements present in a Stack.

VB.NET Queue

Queue is used to store multiple values irrespective of datatypes.
It follows fifo(first in first out).
Enqueue method is used to insert values into queue and Dequeue is used to delete values from queue.

Module Module1

    Sub Main()
        Dim que As New Queue(Of Integer)
        'Enqueue
        que.Enqueue(1)
        que.Enqueue(2)
        que.Enqueue(3)
        que.Enqueue(4)
        'Print
        For Each i As Integer In que
            Console.WriteLine(i)
        Next
        'Count
        Console.WriteLine("No.of elements in queue " & que.Count)
        'Dequeue
        que.Dequeue()
        Console.WriteLine("Dequeue element is " & que.Dequeue())
        'Print
        For Each i As Integer In que
            Console.WriteLine(i)
        Next
        'Count
        Console.WriteLine("No.of elements in queue " & que.Count)
        'Peek
        que.Peek()
        Console.WriteLine("Peek element is " & que.Peek())
        'Print
        For Each i As Integer In que
            Console.WriteLine(i)
        Next
        'Count
        Console.WriteLine("No.of elements in queue " & que.Count)
        'Clear
        que.Clear()
        'Count
        Console.WriteLine("No.of elements after clearing are  " & que.Count)
        Console.ReadLine()
    End Sub

End Module

Output

1
2
3
4
No.of elements in queue 4
Dequeue element is 2
3
4
No.of elements in queue 2
Peek element is 3
3
4
No.of elements in queue 2
No.of elements after clearing are  0

VB.NET Dictionary

Dictionary is used to store values with keys.
Values can be retreived using keys.

VB.NET Dictionary example program

Module Module1

    Sub Main()
        Dim dict As New Dictionary(Of Integer, String)
        'add()
        dict.Add(1, "a")
        dict.Add(2, "b")
        dict.Add(3, "c")
        dict.Add(4, "d")
        'Print
        For Each j As Integer In dict.Keys
            Console.WriteLine(j & dict(j))
        Next
        'count
        Console.WriteLine("No.of items  " & dict.Count)
        'remove()
        dict.Remove(2)
        'print
        For Each j As Integer In dict.Keys
            Console.WriteLine(j & dict(j))
        Next
        'count
        Console.WriteLine("No.of items after removing " & dict.Count)
        'clear
        dict.Clear()
        Console.WriteLine("No.of items " & dict.Count)
        Console.ReadLine()
    End Sub

End Module

Output

1a
2b
3c
4d
No.of items  4
1a
3c
4d
No.of items after removing 3
No.of items 0

VB.NET List ( Generic Collection )

List is a generic collection used to store multiple elements of specific datatype dynamically using Add method.

VB.NET List example program

Module Module1

    Sub Main()
        Dim lis As New List(Of String)
        'add()
        lis.Add("A")
        lis.Add("B")
        lis.Add("C")
        'Print
        For Each s As String In lis
            Console.WriteLine(s)
        Next
        'Count
        Console.WriteLine("No.of items in list " & lis.Count)
        'insert()
        lis.Insert(2, "D")
        'Console.WriteLine("inserted location is  " & lis.Insert())
        'print
        For Each s As String In lis
            Console.WriteLine(s)
        Next
        'count
        Console.WriteLine("No.of items after insertion " & lis.Count)
        'remove()
        lis.Remove("B")
        'print
        For Each s As String In lis
            Console.WriteLine(s)
        Next
        'count
        Console.WriteLine("No.of items after removing " & lis.Count)
        'remove at()
        lis.RemoveAt(0)
        'print
        For Each s As String In lis
            Console.WriteLine(s)
        Next
        'count
        Console.WriteLine("No. of items removed " & lis.Count)
        'clear
        lis.Clear()
        'count
        Console.WriteLine("No. of items present after clearing " & lis.Count)
        Console.ReadLine()
    End Sub

End Module

Output

A
B
C
No.of items in list 3
A
B
D
C
No.of items after insertion 4
A
D
C
No.of items after removing 3
D
C
No.of items removed 2
No.of items present after clearing 0.