Any way to make this working code simpler ie the delegate { }?
public partial class Form1 : Form
{
private CodeDevice codeDevice;
public Form1()
{
InitializeComponent();
codeDevice = new CodeDevice();
//subscribe to CodeDevice.ConnectionSuccessEvent and call Form1.SetupDeviceForConnectionSuccessSate when it fires
codeDevice.ConnectionSuccessEvent += new EventHandler(SetupDeviceForConnectionSuccessState);
}
private void SetupDeviceForConnectionSuccessState(object sender, EventArgs args)
{
MessageBox.Show("It worked");
}
private void button1_Click(object sender, EventArgs e)
{
codeDevice.test();
}
}
public class CodeDevice
{
public event EventHandler ConnectionSuccessEvent = delegate { };
public void ConnectionSuccess()
{
ConnectionSuccessEvent(this, new EventArgs());
}
public void test()
{
System.Threading.Thread.Sleep(1000);
ConnectionSuccess();
}
}
WinForm event subscription to another class
How to subscribe to other class' events in c#?
If don't think you could simplyfy:
public event EventHandler ConnectionSuccessEvent = delegate { }
even in c#3 + you could only do
public event EventHandler ConnectionSuccessEvent = () => { }
However you could simplify
codeDevice.ConnectionSuccessEvent += new EventHandler(SetupDeviceForConnectionSuccessState);
to
codeDevice.ConnectionSuccessEvent += SetupDeviceForConnectionSuccessState;
Related
I have a two classes.In one class i am creating and raising an event as follows :
CustomerAdd Class
public class CustomerAdd
{
public delegate void Done(object Sender, EventArgs e);
public event Done ListUpdated;
public void UpdateNewList()
{
//adding items to a generic List<T>,code removed as not relevant to post
//and raising the event afterwards
if (ListUpdated != null)
{
ListUpdated(this, EventArgs.Empty);
}
}
}
MyWindow Class
public class MyWindow
{
private void SaveToDisk()
{
CustomerAdd cuss = new CustomerAdd();
cuss.ListUpdated += new CustomerAdd.Done(DisplayDetails);
cuss.UpdateNewList();
}
private void DisplayDetails()
{
//other codes here
}
}
Now, when i call the SaveToDisk method from MyWIndow class,(as i am subscribing DisplayDetails method to the ListUpDated event) , DisplayDetails is not called. The debugger shows that ListUpdated is null. I have searched for hours and failed to come up with a solution.I followed this link but still ListUpdated is null. Any guidance/help would be highly appreciated.
It works:
using System;
namespace ConsoleApp2
{
class Program
{
public class CustomerAdd1
{
public delegate void Done(object Sender, EventArgs e);
public event Done ListUpdated;
public void UpdateNewList()
{
//adding items to a generic List<T>,code removed as not relevant to post
//and raising the event afterwards
if (ListUpdated != null)
{
ListUpdated(this, EventArgs.Empty);
}
}
}
public class CustomerAdd
{
public void SaveToDisk()
{
CustomerAdd1 cuss = new CustomerAdd1();
cuss.ListUpdated += new CustomerAdd1.Done(DisplayDetails);
cuss.UpdateNewList();
}
private void DisplayDetails(object Sender, EventArgs e)
{
Console.WriteLine("Test");
}
}
static void Main(string[] args)
{
var c = new CustomerAdd();
c.SaveToDisk();
Console.ReadLine();
}
}
}
Try this:
using System;
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
CustomerReceive cr = new CustomerReceive();
cr.SaveToDisk();
}
}
public class CustomerAdd
{
public delegate void Done(object Sender, EventArgs e);
public event Done ListUpdated;
public void UpdateNewList()
{
//adding items to a generic List<T>,code removed as not relevant to post
//and raising the event afterwards
if (ListUpdated != null)
{
ListUpdated.Invoke(this, EventArgs.Empty);
}
}
}
public class CustomerReceive
{
public void SaveToDisk()
{
CustomerAdd cuss = new CustomerAdd();
cuss.ListUpdated += new CustomerAdd.Done(DisplayDetails);
cuss.UpdateNewList();
}
private void DisplayDetails(object Sender, EventArgs e)
{
int k = 0;
}
}
}
You need to do a good read on delegates and events because this is not working when there are more listeners
I've created event as bellow and want to listen to it and execute method in another class when it fires
but saveEvent always comes to be null and it doesn't fire
I don't know what I've missed
here's my first class has button
internal partial class OpenSaveReportWizardForm : Form
{
public event EventHandler saveEvent;
private void saveButton_Click(object sender, EventArgs e)
{
saveEvent?.Invoke(this, e);
}
}
and here's the second class where I want to listen to saveEvent
internal class Database
{
public Database()
{
Program._wizardForm.saveEvent += (sender, e) => HandleSaveMethod( );
}
public void HandleSaveMethod()
{
// do something
}
here's where I open the form
internal class Program
{
public static OpenSaveReportWizardForm _wizardForm;
private static void Main()
{
OpenFileCommandHandler();
}
void OpenFileCommandHandler()
{
_wizardForm = new OpenSaveReportWizardForm( );
_wizardForm.ShowDialog();
}
}
Because you disposed wizardForm, after that event is cleared.
You should write next code:
internal class Database
{
private bool _isDisposed;
private OpenSaveReportWizardForm _wizardForm;
public Database()
{
_wizardForm = new OpenSaveReportWizardForm(m_Opening,m_ConnectionProperties,m_ColumnProperties))
_wizardForm.saveEvent += (sender, e) => HandleSaveMethod( );
}
public void HandleSaveMethod()
{
// do something
}
public void Dispose()
{
if(_isDisposed)
return;
_isDisposed = true;
_wizardForm.saveEvent -= HandleSaveMethod;
_wizardForm.Dispose();
}
I have a winform that subscribes to events from a callback interface. I use...
public partial class Form1 : Form
{
MyTestCallBack _callback;
public Form1()
{
InitializeComponent();
//Start otherthread
API.Create()
_callback = new MyTestCallBack();
_callback.MyTestCallBackEvent += callback_MyTestCallBackEvent;
_callback.OnUpdate();
}
private callback_MyTestCallBackEvent(MyTestCallBackEventArgs e)
{
if (InvokeRequired)
{
Invoke(new Action(() =>
{
callback_MyTestCallBackEvent(sender, e);
}));
return;
}
label1.Text = e.SomeObject.GetDisplayString();
} }
class MyTestCallBackEventArgs : EventArgs {
public SomeObject SomeObj { get; set; } }
class MyTestCallBack : Callback {
public event EventHandler<MyTestCallBackEventArgs> MyTestCallBackEvent;
protected virtual void OnMyTestCallBackEvent(MyTestCallBackEventArgs e)
{
if (MyTestCallBackEvent != null)
MyTestCallBackEvent(this, e);
}
public void OnUpdate(SomeObject someobj)
{
OnMyTestCallBackEvent(new MyTestCallBackEventArgs { SomeObject = someobj });
}
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
//tried this but still crashes
_callback.MyTestCallBackEvent -= callback_MyTestCallBackEvent;
API.Destroy()
}
When I try to shutdown my form it crashes. "Freezes". I assume it is because of the other thread not shuting down correctly.
How do safely unsubscribe from this event so that I can close down correctly.
To immediately unsubscribe from the event, use:
_callback.MyTestCallBackEvent -= callback_MyTestCallBackEvent;
public partial class Form1 : Form
{
private EventThrower _Thrower;
public Form1()
{
InitializeComponent();
}
private void DoSomething()
{
MessageBox.Show("It worked");
}
private void button1_Click(object sender, EventArgs e)
{
_Thrower = new EventThrower();
//using lambda expression..need to use .NET2 so can't use this.
_Thrower.ThrowEvent += (sender2, args) => { DoSomething(); };
var eventThrower = new EventThrower();
eventThrower.test();
}
}
public class EventThrower
{
public delegate void EventHandler(object sender, EventArgs args);
public event EventHandler ThrowEvent = delegate { };
public void SomethingHappened()
{
ThrowEvent(this, new EventArgs());
}
public void test()
{
System.Threading.Thread.Sleep(1000);
SomethingHappened();
}
}
I'm trying to get my winform UI to subscribe to an event in EventThrower class. DoSomething never fires.
How to subscribe to other class' events in c#?
The event is not static, one instance of the EventHandler exists for each instance of EventThrower.
You subscribe to the event on _Thrower, yet you create a new instance of EventThrower and call test() on that instance. You never subscribed to the event on that instance, so your handler doesn't run.
It should be:
_Thrower.ThrowEvent += (sender2, args) => { DoSomething(); };
_Thrower.test();
This is because you create a new EventThrower before calling test.
If you change:
var eventThrower = new EventThrower();
eventThrower.test();
to:
_Thrower.test();
It will call DoSomething.
Is there a way to give a User Control custom events, and invoke the event on a event within the user control. (I'm not sure if invoke is the correct term)
public partial class Sample: UserControl
{
public Sample()
{
InitializeComponent();
}
private void TextBox_Validated(object sender, EventArgs e)
{
// invoke UserControl event here
}
}
And the MainForm:
public partial class MainForm : Form
{
private Sample sampleUserControl = new Sample();
public MainForm()
{
this.InitializeComponent();
sampleUserControl.Click += new EventHandler(this.CustomEvent_Handler);
}
private void CustomEvent_Handler(object sender, EventArgs e)
{
// do stuff
}
}
Aside from the example that Steve posted, there is also syntax available which can simply pass the event through. It is similar to creating a property:
class MyUserControl : UserControl
{
public event EventHandler TextBoxValidated
{
add { textBox1.Validated += value; }
remove { textBox1.Validated -= value; }
}
}
I believe what you want is something like this:
public partial class Sample: UserControl
{
public event EventHandler TextboxValidated;
public Sample()
{
InitializeComponent();
}
private void TextBox_Validated(object sender, EventArgs e)
{
// invoke UserControl event here
if (this.TextboxValidated != null) this.TextboxValidated(sender, e);
}
}
And then on your form:
public partial class MainForm : Form
{
private Sample sampleUserControl = new Sample();
public MainForm()
{
this.InitializeComponent();
sampleUserControl.TextboxValidated += new EventHandler(this.CustomEvent_Handler);
}
private void CustomEvent_Handler(object sender, EventArgs e)
{
// do stuff
}
}