我需要疑難解答代碼的幫助。我有3個班。 1類是帶有進度條的WinForm。第2類是事件發生的地方。第3類是進展的EventArg。該程序沒有任何錯誤編譯,但是當我點擊按鈕時,進度條不會移動!C#進度條基於事件和delgate不工作
namespace WindowsFormsApplication1
{
class Class1
{
//Declaring a delegate
public delegate void StatusUpdateHandler(object sender, ProgressEventArgs e);
//Declaraing an event
public event StatusUpdateHandler OnUpdateStatus;
public int recno;
public void Func()
{
//time consuming code
for (recno = 0; recno <= 100; recno++)
{
UpdateStatus(recno);
}
}
public void UpdateStatus(int recno)
{
// Make sure someone is listening to event
if (OnUpdateStatus == null) return; <--------------OnUpdateStatus is always null not sure why?
ProgressEventArgs args = new ProgressEventArgs(recno);
OnUpdateStatus(this, args);
}
}
}
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
private Class1 testClass;
public Form1()
{
InitializeComponent();
testClass = new Class1();
testClass.OnUpdateStatus += new Class1.StatusUpdateHandler(UpdateStatus);
}
public void button1_Click(object sender, EventArgs e)
{
Class1 c = new Class1();
c.Func();
}
public void UpdateStatus(object sender, ProgressEventArgs e)
{
progressBar1.Minimum = 0;
progressBar1.Maximum = 100;
progressBar1.Value = e.Recno;
}
}
}
namespace WindowsFormsApplication1
{
public class ProgressEventArgs : EventArgs
{
public int Recno { get; private set; }
public ProgressEventArgs(int recno)
{
Recno = recno;
}
}
}
不要委託類型;相反,使用'EventHandler' –
SLaks