MethodInvoker Delegasikan

Definisi

Ruang nama:

System.Windows.Forms

Rakitan:

System.Windows.Forms.dll

Mewakili delegasi yang dapat menjalankan metode apa pun dalam kode terkelola yang dinyatakan batal dan tidak mengambil parameter.

public delegate void MethodInvoker();

public delegate void MethodInvoker();

type MethodInvoker = delegate of unit -> unit

Public Delegate Sub MethodInvoker()

Contoh

Contoh kode berikut menunjukkan cara menggunakan MethodInvoker untuk memanggil metode yang memperbarui bilah judul formulir aplikasi.

public partial class Form1 : Form
{
    public Form1()
    {
        // Create a timer that will call the ShowTime method every second.
        var timer = new System.Threading.Timer(ShowTime, null, 0, 1000);           
    }

    private void ShowTime(object x)
    {
        // Don't do anything if the form's handle hasn't been created 
        // or the form has been disposed.
        if (!this.IsHandleCreated || this.IsDisposed) return;
        
        // Invoke an anonymous method on the thread of the form.
        this.Invoke((MethodInvoker) delegate
        {
            // Show the current time in the form's title bar.
            this.Text = DateTime.Now.ToLongTimeString();
        });
    }
}

Partial Public Class Form1
    Inherits System.Windows.Forms.Form

    Public Sub New()
        ' Create a timer that will call the ShowTime method every second.
        Dim timer As System.Threading.Timer = _
            New System.Threading.Timer(AddressOf ShowTime, Nothing, 0, 1000)
    End Sub

    Sub ShowTime(ByVal x As Object)
        ' Don't do anything if the form's handle hasn't been created 
        ' or the form has been disposed.
        If (Not Me.IsHandleCreated OrElse Me.IsDisposed) Then Return

        ' Create the method invoker.
        ' The method body shows the current time in the forms title bar.
        Dim mi As MethodInvoker = AddressOf UpdateFormText

        Me.Invoke(mi)
    End Sub

    Sub UpdateFormText()
        Me.Text = DateTime.Now.ToLongTimeString()
    End Sub
End Class

Keterangan

MethodInvoker menyediakan delegasi sederhana yang digunakan untuk memanggil metode dengan daftar parameter yang dibatalkan. Delegasi ini dapat digunakan saat melakukan panggilan ke metode kontrol Invoke , atau ketika Anda memerlukan delegasi sederhana tetapi tidak ingin menentukannya sendiri.

Metode Ekstensi