Kỹ thuật thao tác với Dictionary Collection

[code language=”vb” highlight=”25,26,27,28″] Module MinhHoangBlog

Sub Main()

‘ Declare List data
Dim listData As New List(Of String) From
{
{"first:1"},
{"second:2"},
{"third:1"},
{"first:2"},
{"first:3"},
{"third:2"}
}

‘ Declare mapData: Key is String, Value is List<int>
Dim mapData As New Dictionary(Of String, List(Of Integer))

‘ Get data of mapData
For Each item In listData

‘ Split item by colon
Dim parts() As String = item.Split( ":" )

If Not mapData.ContainsKey(parts(0)) Then
mapData.Add(parts(0), New List(Of Integer))
End If
mapData(parts(0)).Add(parts(1))

Next

‘ Print data of mapData
For Each kvp As KeyValuePair(Of String, List(Of Integer)) In mapData

‘ Declare Keyis String
Dim key = kvp.Key

‘ Declare Value is List<int>
Dim listVal As List(Of Integer) = kvp.Value

Console.WriteLine("・Key: {0}", key)
For Each item In listVal
Console.WriteLine(vbTab & "Value: {0}", item)
Next

Next

Console.ReadKey()

End Sub

End Module
[/code]

[code language=”vb” highlight=”7,15,18,24,30,33,36,46,56″] Imports System.Runtime.CompilerServices

Module MinhHoangBlog

Sub Main()

‘ Declare and initialize the value of a dictionary
Dim mapStudents As New Dictionary(Of Integer, String) From
{
{123, "Tom"},
{444, "Jerry"},
{555, "Peter"}
}

‘ Add new data to dictionary
mapStudents.Add( 666, "Marry" )

‘ Print Value based on Key
Console.WriteLine(mapStudents(444))　 ‘Output: Jerry

‘ New Line
Console.WriteLine()

‘ Print Key and Value
For Each stu In mapStudents
Console.WriteLine(stu.Key & " = " & stu.Value)
Next

‘ Get Key-Value using LINQ
Dim result1 As KeyValuePair(Of Integer, String) = mapStudents.Single(Function(item) item.Key = 444)

‘ Get Key-Value using extension method
Dim result2 As KeyValuePair(Of Integer, String) = mapStudents.GetValueFromKey(444)

‘ Update value of map data based on key
Dim searchKey As Integer = result2.Key
If mapStudents.ContainsKey(searchKey) Then
‘ 値更新
mapStudents(searchKey) = "minhhn.com"
End If

‘ New Line
Console.WriteLine()

‘ Iterate in Dictionary
For Each kvp As KeyValuePair(Of Integer, String) In mapStudents
Dim key As Integer = kvp.Key
Dim val As String = kvp.Value

‘ Do whatever you want with key, val:
Console.WriteLine("{0} = {1}", key, val)
Next

‘ Loop by key
For Each iKey As Integer In mapStudents.Keys
Dim val As String = mapStudents(iKey)
‘…
‘…..Write logic codes Here….
Next

Console.ReadKey()

End Sub

‘ Extension method
”’ <summary>データマップのキーを基にして値を取得する</summary>
”’ <param name="mapData">データマップ</param>
”’ <param name="key">キー</param>
”’ <returns>値</returns>
<Extension()>
Public Function GetValueFromKey(Of TKey, TValue)(mapData As Dictionary(Of TKey, TValue), key As TKey) As KeyValuePair(Of TKey, TValue)
Dim value As TValue
If mapData.TryGetValue(key, value) Then
Return New KeyValuePair(Of TKey, TValue)(key, value)
End If
Return Nothing
End Function

End Module
[/code]