Description
Collections means a Group of Elements or Items which are stored in the memory. We can control the elements in the collections by using the index. The Collection is a type of class. All the types of collections are implemented from the namespace System.Collections.Following are the types of classes available in collections.
| Classes | Description |
|---|---|
| ArrayList | Used to add and remove items from a list using an Index |
| SortedList | Used as Key and Index to access the items in a list. |
| BitArray | Used to represents an array of the Binary representation. |
| Queue | Used to represent elements in a First In First Out format. |
| Hashtable | Used to access elements by using Key and Value. |
| Stack | Used to represent elements in a Last In First Out Format. |
Conceptual
figure
The following figure shows you the different types of collections.
Description
ArrayList is utilized to add and remove items from a list using an Index.Following is an example to describe the ArrayList example.
[vbnet]Module Module1
Sub Main()
Dim al As ArrayList = New ArrayList()
Dim i As Integer
Console.WriteLine("Inserting some numbers:")
al.Add(45)
al.Add(78)
al.Add(33)
al.Add(56)
al.Add(12)
al.Add(23)
al.Add(9)
Console.WriteLine("Capacity: {0} ", al.Capacity)
Console.WriteLine("Count: {0}", al.Count)
Console.Write("Content: ")
For Each i In al
Console.Write("{0} ", i)
Next i
Console.WriteLine()
Console.Write("Sorted Content: ")
al.Sort()
For Each i In al
Console.Write("{0} ", i)
Next i
Console.WriteLine()
Console.ReadKey()
End Sub
End Module
[/vbnet]
Output:
Description
SortedList is utilized as Key and Index to access the items in a list.Following is an example which describes more concept regarding SortedList.
[vbnet]Module Module1
Sub Main()
Dim sl As SortedList = New SortedList()
sl.Add("001", "Zara Ali")
sl.Add("002", "Abida Rehman")
sl.Add("003", "Joe Holzner")
sl.Add("004", "Mausam Benazir Nur")
sl.Add("005", "M. Amlan")
sl.Add("006", "M. Arif")
sl.Add("007", "Ritesh Saikia")
If (sl.ContainsValue("Nuha Ali")) Then
Console.WriteLine("This student name is already in the list")
Else
sl.Add("008", "Nuha Ali")
End If
' Get a collection of the keys.
Dim key As ICollection = sl.Keys
Dim k As String
For Each k In key
Console.WriteLine(" {0} : {1}", k, sl(k))
Next k
Console.ReadKey()
End Sub
End Module[/vbnet]
Output:
Description
BitArray is utilized to represents an array of the Binary representation.Following is an example which describes more about BitArray.
[vbnet]Module Module1
Sub Main()
'creating two bit arrays of size 8
Dim ba1 As BitArray = New BitArray(8)
Dim ba2 As BitArray = New BitArray(8)
Dim a() As Byte = {60}
Dim b() As Byte = {13}
'storing the values 60, and 13 into the bit arrays
ba1 = New BitArray(a)
ba2 = New BitArray(b)
'content of ba1
Console.WriteLine("Bit array ba1: 60")
Dim i As Integer
For i = 0 To ba1.Count
Console.Write("{0 } ", ba1(i))
Next i
Console.WriteLine()
'content of ba2
Console.WriteLine("Bit array ba2: 13")
For i = 0 To ba2.Count
Console.Write("{0 } ", ba2(i))
Next i
Console.WriteLine()
Dim ba3 As BitArray = New BitArray(8)
ba3 = ba1.And(ba2)
'content of ba3
Console.WriteLine("Bit array ba3 after AND operation: 12")
For i = 0 To ba3.Count
Console.Write("{0 } ", ba3(i))
Next i
Console.WriteLine()
ba3 = ba1.Or(ba2)
'content of ba3
Console.WriteLine("Bit array ba3 after OR operation: 61")
For i = 0 To ba3.Count
Console.Write("{0 } ", ba3(i))
Next i
Console.WriteLine()
Console.ReadKey()
End Sub
End Module[/vbnet]
Output:
Description
Queue is utilized to represent elements in a First In First Out format.Following is example which describes more.
[vbnet]Module Module1
Sub Main()
Dim q As Queue = New Queue()
q.Enqueue("A")
q.Enqueue("M")
q.Enqueue("G")
q.Enqueue("W")
Console.WriteLine("Current queue: ")
Dim c As Char
For Each c In q
Console.Write(c + " ")
Next c
Console.WriteLine()
q.Enqueue("V")
q.Enqueue("H")
Console.WriteLine("Current queue: ")
For Each c In q
Console.Write(c + " ")
Next c
Console.WriteLine()
Console.WriteLine("Removing some values ")
Dim ch As Char
ch = q.Dequeue()
Console.WriteLine("The removed value: {0}", ch)
ch = q.Dequeue()
Console.WriteLine("The removed value: {0}", ch)
Console.ReadKey()
End Sub
End Module[/vbnet]
Output:
Description
Hashtable is utilized to access elements by using Key and Value.Following is an example to describe more.
[vbnet]Module Module1
Sub Main()
Dim ht As Hashtable = New Hashtable()
Dim k As String
ht.Add("001", "Zara Ali")
ht.Add("002", "Abida Rehman")
ht.Add("003", "Joe Holzner")
ht.Add("004", "Mausam Benazir Nur")
ht.Add("005", "M. Amlan")
ht.Add("006", "M. Arif")
ht.Add("007", "Ritesh Saikia")
If (ht.ContainsValue("Nuha Ali")) Then
Console.WriteLine("This student name is already in the list")
Else
ht.Add("008", "Nuha Ali")
End If
' Get a collection of the keys.
Dim key As ICollection = ht.Keys
For Each k In key
Console.WriteLine(" {0} : {1}", k, ht(k))
Next k
Console.ReadKey()
End Sub
End Module
[/vbnet]
Output:
Description
Stack is utilized to represent elements in a Last In First Out Format.Following is an example which describes more.
[vbnet]Module Module1
Sub Main()
Dim st As Stack = New Stack()
st.Push("A")
st.Push("M")
st.Push("G")
st.Push("W")
Console.WriteLine("Current stack: ")
Dim c As Char
For Each c In st
Console.Write(c + " ")
Next c
Console.WriteLine()
st.Push("V")
st.Push("H")
Console.WriteLine("The next poppable value in stack: {0}", st.Peek())
Console.WriteLine("Current stack: ")
For Each c In st
Console.Write(c + " ")
Next c
Console.WriteLine()
Console.WriteLine("Removing values ")
st.Pop()
st.Pop()
st.Pop()
Console.WriteLine("Current stack: ")
For Each c In st
Console.Write(c + " ")
Next c
Console.ReadKey()
End Sub
End Module[/vbnet]
Output:
Points
- Count is the property of Stack that utilized to track number of elements from the stack.
- Stack represents last in first out mechanism.
- Queue represents first in first out mechanism.
- To implement an associative array hash table will be utilized.