来自其他类的事件被触发时通知

我有

class A { B b; //call this Method when b.Button_click or b.someMethod is launched private void MyMethod() { } ?? } Class B { //here ie a button is pressed and in Class A //i want to call also MyMethod() in Class A after the button is pressed private void Button_Click(object o, EventArgs s) { SomeMethod(); } public void SomeMethod() { } ?? } 

A类有一个B类实例。

如何才能做到这一点？

Answer 1

你需要在类’B’上声明一个公共事件 – 并让类’A’订阅它：

像这样的东西：

 class B { //A public event for listeners to subscribe to public event EventHandler SomethingHappened; private void Button_Click(object o, EventArgs s) { //Fire the event - notifying all subscribers if(SomethingHappened != null) SomethingHappened(this, null); } .... class A { //Where B is used - subscribe to it's public event public A() { B objectToSubscribeTo = new B(); objectToSubscribeTo.SomethingHappened += HandleSomethingHappening; } public void HandleSomethingHappening(object sender, EventArgs e) { //Do something here } .... 

Answer 2

你需要三件事（在代码中用注释标记）：

1. 在B类中声明事件
2. 发生事件时在B类中引发事件（在您的情况下 – 执行Button_Click事件处理程序）。 请记住，您需要validation是否存在任何订户。 否则，您将在引发事件时获得NullReferenceException。
3. 订阅B类事件。您需要有B类实例，甚至您想要订阅（另一个选项 – 静态事件，但这些事件将由B类的所有实例引发）。

码：

 class A { B b; public A(B b) { this.b = b; // subscribe to event b.SomethingHappened += MyMethod; } private void MyMethod() { } } class B { // declare event public event Action SomethingHappened; private void Button_Click(object o, EventArgs s) { // raise event if (SomethingHappened != null) SomethingHappened(); SomeMethod(); } public void SomeMethod() { } } 

Answer 3

看看从B级发起的事件

看一下

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处理和提高事件

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