в 16:40, 26 мая 2010

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2010-05-26T12:53:44Z

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==Add different data types to ArrayList==

<source lang="vbnet">Imports System.Collections
public class AddElementsToArrayLista
public Shared Sub Main
Dim alist1 As New ArrayList()
alist1.Add("Hello") "Add a System.String
alist1.Add(714) "Add a System.Int32
alist1.Add(New DateTime(2003, 1, 1)) "Add a System.DateTime
alist1.Add(#1/1/2003#) "Add a System.DateTime
alist1.Add(4.5) "Add a System.Double
alist1.Add(4.5F) "Add a System.Single
Dim o As Object
For Each o In alist1
Console.WriteLine(o & ": " & o.GetType().ToString())
Next
End Sub
End class</source>
<pre class=codeResult>Hello: System.String
714: System.Int32
01/01/2003: System.DateTime
01/01/2003: System.DateTime
4.5: System.Double
4.5: System.Single</pre>

==Add user defined object to ArrayList==

<source lang="vbnet">Imports System.Collections
Structure Person
Dim strLastName As String
Dim strFirstName As String
Dim strPhone As String
Dim strEMail As String
End Structure

public class Test
public Shared Sub Main
Dim alPersons As New ArrayList
Dim udtPerson As New Person
"Add the first person.
With udtPerson
.strLastName = "S"
.strFirstName = "J"
.strPhone = "5"
.strEMail = "j@s.ru"
End With
alPersons.Add(udtPerson)
"Add the second person.
With udtPerson
.strLastName = "J"
.strFirstName = "S"
.strPhone = "5"
.strEMail = "s@s.ru"
End With
alPersons.Add(udtPerson)
"Create the third person.
With udtPerson
.strLastName = "J"
.strFirstName = "K"
.strPhone = "5"
.strEMail = "k@s.ru"
End With
"Insert the third person, but first check if they already exists.
If Not alPersons.Contains(udtPerson) Then
alPersons.Insert(1, udtPerson)
End If
"Remove the first person.
alPersons.RemoveAt(0)
"Display the array list values.
Console.WriteLine("The array list contains " & alPersons.Count & " elements.")
For Each udtPerson In alPersons
Console.WriteLine("NAME: " & udtPerson.strFirstName & " " & udtPerson.strLastName)
Next udtPerson

End Sub
End class</source>
<pre class=codeResult>The array list contains 2 elements.
NAME: K J
NAME: S J</pre>

==Convert ArrayList to array==

<source lang="vbnet">Imports System.Collections
public class Test

public Shared Sub Main
Dim array_list As New ArrayList
array_list.Add("A")
array_list.Add("B")
array_list.Add("C")
" Array object of objects.
Dim astring_array As Array
astring_array = array_list.ToArray()

End Sub

End class</source>

==Remove element in an ArrayList by index==

<source lang="vbnet">Imports System.Collections
Structure Person
Dim strLastName As String
Dim strFirstName As String
Dim strPhone As String
Dim strEMail As String
End Structure

public class Test
public Shared Sub Main
Dim alPersons As New ArrayList
Dim udtPerson As New Person
"Add the first person.
With udtPerson
.strLastName = "S"
.strFirstName = "J"
.strPhone = "5"
.strEMail = "j@s.ru"
End With
alPersons.Add(udtPerson)
"Add the second person.
With udtPerson
.strLastName = "J"
.strFirstName = "S"
.strPhone = "5"
.strEMail = "s@s.ru"
End With
alPersons.Add(udtPerson)
"Create the third person.
With udtPerson
.strLastName = "J"
.strFirstName = "K"
.strPhone = "5"
.strEMail = "k@s.ru"
End With
"Insert the third person, but first check if they already exists.
If Not alPersons.Contains(udtPerson) Then
alPersons.Insert(1, udtPerson)
End If
"Remove the first person.
alPersons.RemoveAt(0)
"Display the array list values.
Console.WriteLine("The array list contains " & alPersons.Count & " elements.")
For Each udtPerson In alPersons
Console.WriteLine("NAME: " & udtPerson.strFirstName & " " & udtPerson.strLastName)
Next udtPerson

End Sub
End class</source>
<pre class=codeResult>The array list contains 2 elements.
NAME: K J
NAME: S J</pre>

==Use ArrayList.Contains to check if a object already exists==

<source lang="vbnet">Imports System.Collections
Structure Person
Dim strLastName As String
Dim strFirstName As String
Dim strPhone As String
Dim strEMail As String
End Structure

public class Test
public Shared Sub Main
Dim alPersons As New ArrayList
Dim udtPerson As New Person
"Add the first person.
With udtPerson
.strLastName = "S"
.strFirstName = "J"
.strPhone = "5"
.strEMail = "j@s.ru"
End With
alPersons.Add(udtPerson)
"Add the second person.
With udtPerson
.strLastName = "J"
.strFirstName = "S"
.strPhone = "5"
.strEMail = "s@s.ru"
End With
alPersons.Add(udtPerson)
"Create the third person.
With udtPerson
.strLastName = "J"
.strFirstName = "K"
.strPhone = "5"
.strEMail = "k@s.ru"
End With
"Insert the third person, but first check if they already exists.
If Not alPersons.Contains(udtPerson) Then
alPersons.Insert(1, udtPerson)
End If
"Remove the first person.
alPersons.RemoveAt(0)
"Display the array list values.
Console.WriteLine("The array list contains " & alPersons.Count & " elements.")
For Each udtPerson In alPersons
Console.WriteLine("NAME: " & udtPerson.strFirstName & " " & udtPerson.strLastName)
Next udtPerson

End Sub
End class</source>
<pre class=codeResult>The array list contains 2 elements.
NAME: K J
NAME: S J</pre>

==Use ArrayList to store objects==

<source lang="vbnet">Option Strict On
Imports System
Imports System.Collections

Public Class Employee
Private myEmpID As Integer
Public Sub New(ByVal empID As Integer)
Me.myEmpID = empID
End Sub "New
Public Overrides Function ToString( ) As String
Return myEmpID.ToString( )
End Function "ToString
Public Property EmpID( ) As Integer
Get
Return myEmpID
End Get
Set(ByVal Value As Integer)
myEmpID = Value
End Set
End Property
End Class "Employee
Class Tester
Shared Sub Main( )
Dim empArray As New ArrayList( )
Dim intArray As New ArrayList( )
Dim i As Integer
For i = 0 To 4
empArray.Add(New Employee(i + 100))
intArray.Add((i * 5))
Next i
For Each i In intArray
Console.Write("{0} ", i.ToString( ))
Next i
Console.WriteLine(ControlChars.Lf)
Dim e As Employee
For Each e In empArray
Console.Write("{0} ", e.ToString( ))
Next e
Console.WriteLine(ControlChars.Lf)
Console.WriteLine("empArray.Capacity: {0}", empArray.Capacity)
End Sub
End Class</source>
<pre class=codeResult>0 5 10 15 20
100 101 102 103 104
empArray.Capacity: 8</pre>

==Use DirectCast to convert ArrayList to array==

<source lang="vbnet">Imports System.Collections
public class Test

public Shared Sub Main
Dim array_list As New ArrayList
array_list.Add("A")
array_list.Add("B")
array_list.Add("C")
" Array of strings.
Dim string_array() As String
string_array = DirectCast(array_list.ToArray(GetType(String)), String())

End Sub

End class</source>

==Use For Each to loop through the ArrayList==

<source lang="vbnet">Imports System.Collections
Structure Person
Dim strLastName As String
Dim strFirstName As String
Dim strPhone As String
Dim strEMail As String
End Structure

public class Test
public Shared Sub Main
Dim alPersons As New ArrayList
Dim udtPerson As New Person
"Add the first person.
With udtPerson
.strLastName = "S"
.strFirstName = "J"
.strPhone = "5"
.strEMail = "j@s.ru"
End With
alPersons.Add(udtPerson)
"Add the second person.
With udtPerson
.strLastName = "J"
.strFirstName = "S"
.strPhone = "5"
.strEMail = "s@s.ru"
End With
alPersons.Add(udtPerson)
"Create the third person.
With udtPerson
.strLastName = "J"
.strFirstName = "K"
.strPhone = "5"
.strEMail = "k@s.ru"
End With
"Insert the third person, but first check if they already exists.
If Not alPersons.Contains(udtPerson) Then
alPersons.Insert(1, udtPerson)
End If
"Remove the first person.
alPersons.RemoveAt(0)
"Display the array list values.
Console.WriteLine("The array list contains " & alPersons.Count & " elements.")
For Each udtPerson In alPersons
Console.WriteLine("NAME: " & udtPerson.strFirstName & " " & udtPerson.strLastName)
Next udtPerson

End Sub
End class</source>
<pre class=codeResult>The array list contains 2 elements.
NAME: K J
NAME: S J</pre>

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в 16:40, 26 мая 2010

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