AboutMyDot.Net

Hashtables are my preferred way to keep informations in memory. I think that they’re powerful and really simple to use.
The Hashtable class resides into the System.Collections namespace and uses an Object as Key and an Object as Value for the items so it’s really versatile and doesn’t give you any constraint about types, you can store all that u want in them.

Imports System.Collections
 
'Create a simple class
Public Class Person
    private _Name;
    private _Surname;

    Public Sub New()
        _Name = ""
        _Surname = ""
    End Sub
 
    Public Property Name() As String
        Get
            Return _Name
        End Get
        Set(ByVal Value As String)
            _Name=Value
        End Set
    End Property

    Public Property Surname() As String
        Get
            Return _Surname
        End Get
        Set(ByVal Value As String)
            _Surname=Value
        End Set
    End Property
End Class
 
'Let's assume we have a chief for each sector of an enterprise
'and we want to keep in memory their names
 
public chiefs as new Hashtable
 
public sub CreateChiefsTable()
    dim p1 as new Person
    p1.Name="John"
    p1.Surname="Smith"
    'add the person into the hashtable and identify him
    'with the sector name as key.
    chiefs.Add("Sector Alpha",p1)
 
    dim p2 as new Person
    p2.Name="Michael"
    p2.Surname="Brown"
    'add a second person.
    chiefs.Add("Sector Beta",p2)
end sub
 
'Accessing the data is really simple.
'Create a sub that shows the name and surname of the chief
'of a specific sector.
 
public sub ShowChiefInfo(ByVal Sector as string)
    if chiefs.ContainsKey(Sector) then
        dim p as person
	p=directCast(chiefs(Sector),Person)
	MessageBox.show(p.Name + " " + p.Surname)
    else
	MessageBox.Show("Wrong sector")
    end if
end sub
 
'Cycling the items is easy too
'Create a sub that shows each sector chief info
 
public sub ShowChiefs()
    'cycle all Hastables keys
    for each Sector as string in chiefs.keys
	dim p as person
	p=directCast(chiefs(Sector),Person)
	MessageBox.show(Sector + ": " + p.Name + " " + p.Surname)
    next
end sub
 

Download this code: Hashtable.vb.txt

That’s all.

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