如何使用事件将参数传递给另一个类 [英] How to pass a parameter to another class using events

问题描述

我有一个带有一个按钮的 usercontrol

I have a usercontrol which is having one button

Usercontrolclass.cs

按钮点击事件

  private void btn_OK_Click(object sender, EventArgs e)
        {
            value= Convert.ToDouble(txt_ActualValue.Text);

            if(getvalue!=null)
            getvalue(null, new EventArga());
        }

私有变量

private int value;

属性:

 public double finalvalue
        {
            get
            {
                return value;
            }
        }

MainForm.cs

我正在将该用户控件用于此主表单

I'm using that Usercontrol into this mainform

我需要从此类中获取价值

I need to get the value from this class

在构造函数中:

Usercontrolclass.getvalue+=Usercontrolclass_getvalue;

在方法中:

 private void   UserControlclass_getvalue()
    {
      here I need to get the "value";

     int myval = Usercontrolclass.finalvalue;  // I can get like this
    }

我的问题是不使用属性，只是将一个参数传递给事件参数，然后将值传递给mainfrom?

my question is without using properties simply pass a parameter into the event arguments and get the value in to the mainfrom?

  if(getvalue!=null)
                getvalue(null, new EventArga(value));

因为我不允许这样做 classname.properties

Because I don't allowed to do like this classname.properties

以及不允许使用此类方法传递参数

as well as don't allowed to pass a parameter using method like this

在Usercontrol类中

in Usercontrol class

 Mainform obj = new Mainform ();
            obj.getvalue(value);

还有其他方法可以做到吗?我的意思是通过使用事件将变量传递给另一个类?

Is there any other way to do this? I mean pass a variable to another class by using events?

推荐答案

您可以创建自己的事件，也可以从 usercontrol 触发它们(在此处事件发生)，然后在您的主表单上放置一个侦听器.

You can make your own events, you can fire them from the usercontrol (here is where the event takes place) and put a listener on your main form.

用户控制:

//You custom event, has to be inside namespace but outside class
public delegate void MyCustomEvent(int value);

public partial class aUserControl : UserControl
{
    //Here you initialize it
    public event MyCustomEvent CustomEvent;

    public aUserControl()
    {
        InitializeComponent();
    }

    private void theButton_Click( object sender, EventArgs e )
    {
        CustomEvent?.Invoke(5);//using magic number for test
        //You can call this anywhere in the user control to fire the event
    }
}

现在在主要形式中，我添加了usercontrol和一个事件侦听器

Now in the main form I added the usercontrol and an event listener

主要形式:

public Form1()
{
    InitializeComponent();

    //Here you add the event listener to your user control
    aUserControl1.CustomEvent += AUserControl1_CustomEvent;
}

private void AUserControl1_CustomEvent( int value )
{
    MessageBox.Show(value.ToString());
    //This is the Main form and I now have the value here 
    //whenever the button is clicked (or event is fired from somewhere else)
}

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