VB.Net/Data Structure/Dictionary

Check if a directory does not exist, create a directory

Imports System.IO
Module Module1

    Sub Main()
        Try
            If (Directory.Exists("D:\test01")) Then
                Console.WriteLine("D:\test01 already exists")
            Else
                Directory.CreateDirectory("C:\test01")
            End If
            Console.WriteLine("Directories created")
        Catch E As Exception
            Console.WriteLine("Error creating directory")
            Console.WriteLine("Error: {0}", E.Message)
        End Try
    End Sub
End Module

Create directory with drive letter and without drive letter

Imports System.IO
Module Module1
    Sub Main()
        Console.WriteLine("Creating directories...")
        Directory.CreateDirectory("D:\test01")
        Directory.CreateDirectory("D:\Temp\Sample02")
        Directory.CreateDirectory("Sample03")
        Console.WriteLine("Directories created")
    End Sub
End Module

Delete a Directory

Imports System.IO
Module Module1

    Sub Main()
        Try
            Directory.Delete("C:\Sample01", True)
        Catch E As Exception
            Console.WriteLine("Error deleting directory C:\Sample01")
            Console.WriteLine("Error {0}", E.Message)
        End Try
    End Sub
End Module

Get and set current working directory

Imports System.IO
Module Module1
    Sub Main()
        Console.WriteLine("Current directory is {0}", Directory.GetCurrentDirectory())
        Directory.SetCurrentDirectory("C:\")
        Console.WriteLine("Current directory is {0}", Directory.GetCurrentDirectory())
    End Sub
End Module

Get parent directory

Imports System.IO
Module Module1
    Sub Main()
        Dim Current As String
        Dim Parent As DirectoryInfo
        Try
            Current = Directory.GetCurrentDirectory()
            Parent = Directory.GetParent(Current)
            Console.WriteLine("Current directory {0}", Current)
            Console.WriteLine("Parent directory {0}", Parent.FullName)
        Catch E As Exception
            Console.WriteLine("Error determining parent directory")
            Console.WriteLine(E.Message)
        End Try
    End Sub
End Module

List all Directories under a directory

Imports System.IO
Module Module1
    Sub Main()
        Dim Root As New DirectoryInfo("C:\")
        Dim Files As FileInfo() = Root.GetFiles("*.*")
        Dim Dirs As DirectoryInfo() = Root.GetDirectories("*.*")
        Console.WriteLine("Root Directories")
        Dim DirectoryName As DirectoryInfo
        For Each DirectoryName In Dirs
            Try
                Console.Write(DirectoryName.FullName)
                Console.Write(" contains {0} files ", DirectoryName.GetFiles().Length)
                Console.WriteLine(" and {0} subdirectories ", DirectoryName.GetDirectories().Length)
            Catch E As Exception
                Console.WriteLine("Error accessing")
            End Try
        Next
    End Sub
End Module

List all files under a directory

Imports System.IO
Module Module1
    Sub Main()
        Dim Root As New DirectoryInfo("C:\")
        Dim Files As FileInfo() = Root.GetFiles("*.*")
        Dim Dirs As DirectoryInfo() = Root.GetDirectories("*.*")
        Console.WriteLine("Root Files")
        Dim Filename As FileInfo
        For Each Filename In Files
            Try
                Console.Write(Filename.FullName)
                Console.Write(" Size: {0} bytes", Filename.Length)
                Console.WriteLine(" Last use: {0}", Filename.LastAccessTime)
            Catch E As Exception
                Console.WriteLine("Error accessing File")
            End Try
        Next
    End Sub
End Module

Make Dictionary based on your own Object

Imports System
Imports System.Collections
Imports System.Collections.Generic
Public Class MainClass
    
    Shared Sub Main(ByVal args As String())
        Dim dict As New StudentDictionary
        dict.Add("113-11-1111", New Student("A", "a"))
        dict.Add("222-22-2222", New Student("B", "b"))
        dict.Add("333-33-3333", New Student("C", "c"))
        dict.Add("444-44-4444", New Student("D", "d"))
        Dim student As Student = dict.Item("365-76-5476")
        Console.WriteLine(student.ToString)
    End Sub
End Class
  
Public Class Student
    Private m_FirstName As String
    Private m_LastName As String
    Public Sub New(ByVal first_name As String, ByVal last_name As String)
        m_FirstName = first_name
        m_LastName = last_name
    End Sub
    Public Overrides Function ToString() As String
        Return m_FirstName & " " & m_LastName
    End Function
End Class
Public Class StudentDictionary
    Inherits System.Collections.DictionaryBase
    " Add a Dictionary entry.
    Public Sub Add(ByVal new_key As String, ByVal new_student As Student)
        Dictionary.Add(new_key, new_student)
    End Sub
    " Return an object with the given key.
    Default Public Property Item(ByVal key As String) As Student
        Get
            Return DirectCast(Dictionary.Item(key), Student)
        End Get
        Set(ByVal Value As Student)
            Dictionary.Item(key) = Value
        End Set
    End Property
    " Return a collection containing the Dictionary"s keys.
    Public ReadOnly Property Keys() As ICollection
        Get
            Return Dictionary.Keys
        End Get
    End Property
    " Return a collection containing the Dictionary"s values.
    Public ReadOnly Property Values() As ICollection
        Get
            Return Dictionary.Values
        End Get
    End Property
    " Return True if the Dictionary contains this Student.
    Public Function Contains(ByVal key As String) As Boolean
        Return Dictionary.Contains(key)
    End Function
    " Remove this entry.
    Public Sub Remove(ByVal key As String)
        Dictionary.Remove(key)
    End Sub
End Class

Your own Generic List Dictionary

Imports System
Imports System.Collections
Imports System.Collections.Generic
Imports System.Collections.Specialized

Public Class MainClass
    
    Shared Sub Main(ByVal args As String())
        Dim dict As New StudentListDictionary
        dict.Add("111-11-1111", New Student("A", "A"))
        dict.Add("333-22-3333", New Student("B", "B"))
        dict.Add("444-44-4444", New Student("C", "C"))
        dict.Add("555-55-5555", New Student("D", "D"))
        Dim student As Student = dict.Item("111-11-1111")
        Console.WriteLine(student.ToString)
    End Sub
End Class
  
Public Class Student
    Private m_FirstName As String
    Private m_LastName As String
    Public Sub New(ByVal first_name As String, ByVal last_name As String)
        m_FirstName = first_name
        m_LastName = last_name
    End Sub
    Public Overrides Function ToString() As String
        Return m_FirstName & " " & m_LastName
    End Function
End Class
Public Class StudentListDictionary
    Inherits ListDictionary
    " Add a Dictionary entry.
    Public Shadows Sub Add(ByVal new_key As String, ByVal new_student As Student)
        MyBase.Add(new_key, new_student)
    End Sub
    " Return an object with the given key.
    Default Public Shadows Property Item(ByVal key As String) As Student
        Get
            Return DirectCast(MyBase.Item(key), Student)
        End Get
        Set(ByVal Value As Student)
            MyBase.Item(key) = Value
        End Set
    End Property
    " Return True if the Dictionary contains this Student.
    Public Shadows Function Contains(ByVal key As String) As Boolean
        Return MyBase.Contains(key)
    End Function
    " Remove this entry.
    Public Shadows Sub Remove(ByVal key As String)
        MyBase.Remove(key)
    End Sub
End Class