ListBox.Sort Método
Definição
Importante
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Classifica os itens no ListBox.
protected:
virtual void Sort();protected virtual void Sort ();abstract member Sort : unit -> unit
override this.Sort : unit -> unitProtected Overridable Sub Sort ()Exemplos
O exemplo de código a seguir demonstra o uso do Sort método. O exemplo demonstra a ListBox herdação da classe e a substituição do Sort método na classe derivada para executar uma classificação definida pelo usuário. Para executar este exemplo, cole o código a seguir em um formulário vazio.
// The following code example demonstrates using the ListBox.Sort method
// by inheriting from the ListBox class and overriding the Sort method.
using namespace System::Drawing;
using namespace System::Windows::Forms;
// This class inherits from ListBox and implements a different
// sorting method. Sort will be called by setting the class's Sorted
// property to True.
public ref class SortByLengthListBox: public ListBox
{
public:
SortByLengthListBox()
: ListBox()
{}
protected:
// Overrides the parent class Sort to perform a simple
// bubble sort on the length of the string contained in each item.
virtual void Sort() override
{
if ( Items->Count > 1 )
{
bool swapped;
do
{
int counter = Items->Count - 1;
swapped = false;
while ( counter > 0 )
{
// Compare the items' length.
if ( Items[ counter ]->ToString()->Length < Items[ counter - 1 ]->ToString()->Length )
{
// Swap the items.
Object^ temp = Items[ counter ];
Items[ counter ] = Items[ counter - 1 ];
Items[ counter - 1 ] = temp;
swapped = true;
}
// Decrement the counter.
counter -= 1;
}
}
while ( (swapped == true) );
}
}
};
public ref class Form1: public System::Windows::Forms::Form
{
internal:
System::Windows::Forms::Button^ Button1;
SortByLengthListBox^ sortingBox;
public:
Form1()
: Form()
{
this->Button1 = gcnew System::Windows::Forms::Button;
this->sortingBox = gcnew SortByLengthListBox;
this->SuspendLayout();
this->Button1->Location = System::Drawing::Point( 64, 16 );
this->Button1->Name = "Button1";
this->Button1->Size = System::Drawing::Size( 176, 23 );
this->Button1->TabIndex = 0;
this->Button1->Text = "Click me for list sorted by length";
this->Button1->Click += gcnew System::EventHandler( this, &Form1::Button1_Click );
array<Object^>^temp0 = {"System","System.Windows.Forms","System.Xml","System.Net","System.Drawing","System.IO"};
this->sortingBox->Items->AddRange( temp0 );
this->sortingBox->Location = System::Drawing::Point( 72, 48 );
this->sortingBox->Size = System::Drawing::Size( 120, 95 );
this->sortingBox->TabIndex = 1;
this->ClientSize = System::Drawing::Size( 292, 266 );
this->Controls->Add( this->sortingBox );
this->Controls->Add( this->Button1 );
this->Name = "Form1";
this->Text = "Sort Example";
this->ResumeLayout( false );
}
private:
void Button1_Click( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Set the Sorted property to True to raise the overridden Sort
// method.
sortingBox->Sorted = true;
}
};
int main()
{
Application::Run( gcnew Form1 );
}
// The following code example demonstrates using the ListBox.Sort method
// by inheriting from the ListBox class and overriding the Sort method.
using System.Drawing;
using System.Windows.Forms;
public class Form1:
System.Windows.Forms.Form
{
internal System.Windows.Forms.Button Button1;
internal SortByLengthListBox sortingBox;
public Form1() : base()
{
this.Button1 = new System.Windows.Forms.Button();
this.sortingBox =
new SortByLengthListBox();
this.SuspendLayout();
this.Button1.Location = new System.Drawing.Point(64, 16);
this.Button1.Name = "Button1";
this.Button1.Size = new System.Drawing.Size(176, 23);
this.Button1.TabIndex = 0;
this.Button1.Text = "Click me for list sorted by length";
this.Button1.Click += new System.EventHandler(Button1_Click);
this.sortingBox.Items.AddRange(new object[]{"System",
"System.Windows.Forms", "System.Xml", "System.Net",
"System.Drawing", "System.IO"});
this.sortingBox.Location =
new System.Drawing.Point(72, 48);
this.sortingBox.Size =
new System.Drawing.Size(120, 95);
this.sortingBox.TabIndex = 1;
this.ClientSize = new System.Drawing.Size(292, 266);
this.Controls.Add(this.sortingBox);
this.Controls.Add(this.Button1);
this.Name = "Form1";
this.Text = "Sort Example";
this.ResumeLayout(false);
}
public static void Main()
{
Application.Run(new Form1());
}
private void Button1_Click(System.Object sender, System.EventArgs e)
{
// Set the Sorted property to True to raise the overridden Sort
// method.
sortingBox.Sorted = true;
}
}
// This class inherits from ListBox and implements a different
// sorting method. Sort will be called by setting the class's Sorted
// property to True.
public class SortByLengthListBox:
ListBox
{
public SortByLengthListBox() : base()
{
}
// Overrides the parent class Sort to perform a simple
// bubble sort on the length of the string contained in each item.
protected override void Sort()
{
if (Items.Count > 1)
{
bool swapped;
do
{
int counter = Items.Count - 1;
swapped = false;
while (counter > 0)
{
// Compare the items' length.
if (Items[counter].ToString().Length
< Items[counter-1].ToString().Length)
{
// Swap the items.
object temp = Items[counter];
Items[counter] = Items[counter-1];
Items[counter-1] = temp;
swapped = true;
}
// Decrement the counter.
counter -= 1;
}
}
while((swapped==true));
}
}
}
Imports System.Drawing
Imports System.Windows.Forms
Public Class Form1
Inherits System.Windows.Forms.Form
Public Sub New()
MyBase.New()
Me.Button1 = New System.Windows.Forms.Button
Me.SortByLengthListBox1 = New SortByLengthListBox
Me.SuspendLayout()
Me.Button1.Location = New System.Drawing.Point(64, 16)
Me.Button1.Name = "Button1"
Me.Button1.Size = New System.Drawing.Size(176, 23)
Me.Button1.TabIndex = 0
Me.Button1.Text = "Click me for list sorted by length"
Me.SortByLengthListBox1.Items.AddRange(New Object() {"System", _
"System.Windows.Forms", "System.Xml", _
"System.Net", "System.Drawing", "System.IO"})
Me.SortByLengthListBox1.Location = New System.Drawing.Point(72, 48)
Me.SortByLengthListBox1.Name = "SortByLengthListBox1"
Me.SortByLengthListBox1.Size = New System.Drawing.Size(120, 95)
Me.SortByLengthListBox1.TabIndex = 1
Me.ClientSize = New System.Drawing.Size(292, 266)
Me.Controls.Add(Me.SortByLengthListBox1)
Me.Controls.Add(Me.Button1)
Me.Name = "Form1"
Me.Text = "Sort Example"
Me.ResumeLayout(False)
End Sub
Friend WithEvents Button1 As System.Windows.Forms.Button
Friend WithEvents SortByLengthListBox1 As SortByLengthListBox
Public Shared Sub Main()
Application.Run(New Form1)
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
' Set the Sorted property to True to raise the overridden Sort
' method.
SortByLengthListBox1.Sorted = True
End Sub
End Class
' This class inherits from ListBox and implements a different
' sorting method. Sort will be called by setting the class's Sorted
' property to True.
Public Class SortByLengthListBox
Inherits ListBox
Public Sub New()
MyBase.New()
End Sub
' Overrides the parent class Sort to perform a simple
' bubble sort on the length of the string contained in each item.
Protected Overrides Sub Sort()
If (Items.Count > 1) Then
Dim swapped As Boolean
Do
Dim counter As Integer = Items.Count - 1
swapped = False
While (counter > 0)
' Compare the items' length.
If Items(counter).ToString.Length < _
Items(counter - 1).ToString.Length Then
' If true, swap the items.
Dim temp As Object = Items(counter)
Items(counter) = Items(counter - 1)
Items(counter - 1) = temp
swapped = True
End If
' Decrement the counter.
counter -= 1
End While
Loop While (swapped = True)
End If
End Sub
End Class
Comentários
Sort força a coleção a adicionar cada item de volta a si mesmo se a Sorted propriedade for true. Cada item é inserido na posição correta.
Notas aos Herdeiros
Você pode substituir esse método em sua classe derivada para fornecer sua própria rotina de classificação. Acesse os resultados do método substituído Sort() definindo a Sorted propriedade como true. Ao adicionar itens a um ListBox, é mais eficiente classificar os itens primeiro e, em seguida, adicionar novos itens.