Imports System.Threading
'看名字就知道，这个类干什么用的，多线程应用程序都要用这个类
Public Delegate Function BinaryOp(ByVal x As Integer,ByVal y As Integer) As Integer
Module Module1
Sub main()
Console.WriteLine("***** Async Delegate Invocation *****")
' Print out the ID of the executing thread.
Console.WriteLine("Main() invoked on thread {0}.",Thread.CurrentThread.ManagedThreadId)
Dim b As New BinaryOp(AddressOf Add)
Dim iftAR As IAsyncResult = b.BeginInvoke(10,10,Nothing,Nothing)
' This message will keep printing until
' the Add() method is finished.
Do While Not iftAR.IsCompleted
Console.WriteLine("Doing more work in Main()!")
Thread.Sleep(1000)
Loop
' Now we know the Add() method is complete.
Dim answer As Integer = b.EndInvoke(iftAR)
Console.WriteLine("10 + 10 is {0}.",answer)
Console.ReadLine()
End Sub
Private Function Add(ByVal x As Integer,ByVal y As Integer) As Integer
' Print out the ID of the executing thread.
Console.WriteLine("Add() invoked on thread {0}.",Thread.CurrentThread.ManagedThreadId)
' Pause to simulate a lengthy operation.
Thread.Sleep(5000)
Return x + y
End Function
End Module
