[英]How to call a method on another class using delegates?
假设我有两种形式。 当我按下第一个按钮时,会显示第二个按钮。 但是,我希望能够通过按下它上的按钮来关闭第二个,但它应该在第一个上触发一种方法,该方法负责关闭第二个窗口。 它必须使用委托和事件来完成。 我该怎么做? 谢谢您的帮助。
你的问题不是很清楚..可能对你有帮助。
// Form1 is the 1st form or main form
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
//creat a sample object of FormEXt
var form = new FormExt();
//subscribe its CustomClose Event
form.CustomClose += new FormExt.CloseMeDelegate(form_CustomClose);
//set the text
form.Text = "Samplee 01";
//show the form
form.Show();
//repeat a again
form = new FormExt();
form.CustomClose += new FormExt.CloseMeDelegate(form_CustomClose);
form.Text = "Samplee 02";
form.Show();
}
void form_CustomClose(Form form)
{
//get the form show the titile
MessageBox.Show("Going to Close" + form.Text);
//close the form
form.Close();
}
}
//second form with a button
public class FormExt : Form
{
//creat a delegate which takes form as input
public delegate void CloseMeDelegate(Form form);
//creat event from delegeate set it fake delegate in order to avoid null excpetion
public event CloseMeDelegate CustomClose = delegate {
};
public FormExt() {
//creat a button
var button = new Button() { Text = "Click" , Top = 10 , Left=10 };
//grab button click event
button.Click += delegate
{
//invoke custome close event
CustomClose(this);
};
//add button on the form
this.Controls.Add(button);
}
}
在您的第二个窗口中,声明一个在窗口想要关闭时引发的事件:
// ## Second window ##
public delegate void IssueCloseDelegate(object sender, EventArgs e);
public event IssueCloseDelegate IssueClose;
当按下关闭按钮时,引发此事件:
// ## Second window, button click handler
if (IssueClose != null)
IssueClose(this, EventArgs.Empty);
在第一个窗口中实例化窗口时,注册事件并处理它:
// ## First window ##
//some method
var newWindow = new SecondWindow();
newWindow.IssueClose += NewWindow_IssueClose;
newWindow.Show();
//...
private void NewWindow_IssueClose(object sender, EventArgs e)
{
var closedWindow = (SecondWindow)sender;
closedWindow.Close();
}
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