blocks|key|1712224|text|您可以使用"Shown“事件：MSDN+-+Form.Shown|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1712225|只有在第一次显示窗体时才会引发Shown事件；随后的最小化、最大化、恢复、隐藏、显示或无效和重新绘制将不会引发此事件。|1712226|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.windows.forms.form.shown.aspx^0|F|H|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

You could use the "Shown" event: <a href="http://msdn.microsoft.com/en-us/library/system.windows.forms.form.shown.aspx" rel="noreferrer">MSDN - Form.Shown</a>

"The Shown event is only raised the first time a form is displayed; subsequently minimizing, maximizing, restoring, hiding, showing, or invalidating and repainting will not raise this event."

blocks|key|1497285|text|第一次它不会启动"AfterLoading"，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1497286|它只会注册它来开始下一次加载。|1497287|private+void+Main_Load(object+sender,+System.EventArgs+e)
{
++++//Register+it+to+Start+in+Load+
++++//Starting+from+the+Next+time.
++++this.Activated+%2B=+AfterLoading;
}

private+void+AfterLoading(object+sender,+EventArgs+e)
{
++++this.Activated+-=+AfterLoading;
++++//Write+your+code+here.
}|code-block|syntax|javascript|1497288|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

First time it WILL NOT start "AfterLoading", 
It will just register it to start NEXT Load.

<pre><code>private void Main_Load(object sender, System.EventArgs e)
{
 //Register it to Start in Load 
 //Starting from the Next time.
 this.Activated += AfterLoading;
}

private void AfterLoading(object sender, EventArgs e)
{
 this.Activated -= AfterLoading;
 //Write your code here.
}
</code></pre>

blocks|key|1497244|text|我也遇到了同样的问题，解决方法如下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1497245|实际上，我想显示消息，并在2秒后自动关闭它。为此，我必须生成(动态)简单的表单和一个标签，显示消息，停止消息1500毫秒，以便用户阅读它。并关闭动态创建的表单。显示的事件发生在加载事件之后。所以代码是|1497246|Form+MessageForm+=+new+Form();
MessageForm.Shown+%2B=+(s,+e1)+=>+{+
++++Thread+t+=+new+Thread(()+=>+Thread.Sleep(1500));+
++++t.Start();+
++++t.Join();+
++++MessageForm.Close();+
};|code-block|syntax|javascript|1497247|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I had the same problem, and solved it as follows:

Actually I want to show Message and close it automatically after 2 second. For that I had to generate (dynamically) simple form and one label showing message, stop message for 1500 ms so user read it. And Close dynamically created form. Shown event occur After load event. So code is

<pre><code>Form MessageForm = new Form();
MessageForm.Shown += (s, e1) =&gt; { 
 Thread t = new Thread(() =&gt; Thread.Sleep(1500)); 
 t.Start(); 
 t.Join(); 
 MessageForm.Close(); 
};
</code></pre>

blocks|key|1712196|text|您还可以尝试将代码放在窗体的activated事件中，如果您希望它在窗体被激活时发生。但是，如果只在第一次激活时运行，则需要放入一个布尔值“已执行”检查。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1712197|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You could also try putting your code in the Activated event of the form, if you want it to occur, just when the form is activated. You would need to put in a boolean "has executed" check though if it is only supposed to run on the first activation.

blocks|key|1497384|text|这是一个古老的问题，更多地取决于你何时需要开始你的例程。因为没有人想要空引用异常，所以最好先检查空引用异常，然后根据需要使用；单这一点就可以省去很多麻烦。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1497385|此类问题的最常见原因是，当容器或自定义控件类型尝试访问在自定义类外部初始化的属性时，这些属性尚未初始化，从而可能导致填充空值，甚至可能导致对象类型上的空值引用异常。这意味着你的类在完全初始化之前运行--在你完成属性设置之前。这类问题的另一个可能的原因是什么时候执行自定义图形。|1497386|对于何时在表单加载事件之后开始执行代码的问题，最好的回答是监视WM_Paint消息或直接挂接到paint事件本身。为什么？仅当相对于窗体加载事件完全加载所有模块时，才会触发paint事件。注意:当This.visible+==+true设置为true时，它并不总是true，因此除了隐藏表单之外，根本不会将其用于此目的。|1497387|下面是一个完整的示例，说明如何在窗体加载事件之后开始执行代码。建议您不要不必要地占用paint消息循环，因此我们将创建一个事件，该事件将在该循环之外开始执行您的代码。|1497388|using+System.Windows.Forms;|code-block|syntax|javascript|1497389|命名空间MyProgramStartingPlaceExample+{|1497390|///+<summary>
///+Main+UI+form+object
///+</summary>
public+class+Form1+:+Form
{

++++///+<summary>
++++///+Main+form+load+event+handler
++++///+</summary>
++++public+Form1()
++++{
++++++++//+Initialize+ONLY.+Setup+your+controls+and+form+parameters+here.+Custom+controls+should+wait+for+"FormReady"+before+starting+up+too.
++++++++this.Text+=+"My+Program+title+before+form+loaded";
++++++++//+Size+need+to+see+text.+lol
++++++++this.Width+=+420;

++++++++//+Setup+the+sub+or+fucntion+that+will+handle+your+"start+up"+routine
++++++++this.StartUpEvent+%2B=+StartUPRoutine;

++++++++//+Optional:+Custom+control+simulation+startup+sequence:
++++++++//+Define+your+class+or+control+in+variable.+ie.+var+MyControlClass+new+CustomControl;
++++++++//+Setup+your+parameters+only.+ie.+CustomControl.size+=+new+size(420,+966);+Do+not+validate+during+initialization+wait+until+"FormReady"+is+set+to+avoid+possible+null+values+etc.+
++++++++//+Inside+your+control+or+class+have+a+property+and+assign+it+as+bool+FormReady+-+do+not+validate+anything+until+it+is+true+and+you'll+be+good!+
++++}

++++///+<summary>
++++///+The+main+entry+point+for+the+application+which+sets+security+permissions+when+set.
++++///+</summary>
++++static+void+Main()
++++{
++++++++Application.EnableVisualStyles();
++++++++Application.SetCompatibleTextRenderingDefault(false);
++++++++Application.Run(new+Form1());
++++}


++++#region+"WM_Paint+event+hooking+with+StartUpEvent"++++++++++++
++++//
++++//+Create+a+delegate+for+our+"StartUpEvent"
++++public+delegate+void+StartUpHandler();
++++//
++++//+Create+our+event+handle+"StartUpEvent"
++++public+event+StartUpHandler+StartUpEvent;
++++//
++++//+Our+FormReady+will+only+be+set+once+just+he+way+we+intendded
++++//+Since+it+is+a+global+variable+we+can+poll+it+else+where+as+well+to+determine+if+we+should+begin+code+execution+!!
++++bool+FormReady;
++++//
++++//+The+WM_Paint+message+handler:+Used+mostly+to+paint+nice+things+to+controls+and+screen
++++protected+override+void+OnPaint(PaintEventArgs+e)
++++{
++++++++//+Check+if+Form+is+ready+for+our+code+?
++++++++if+(FormReady+==+false)+//+Place+a+break+point+here+to+see+the+initialized+version+of+the+title+on+the+form+window
++++++++{
++++++++++++//+We+only+want+this+to+occur+once+for+our+purpose+here.
++++++++++++FormReady+=+true;
++++++++++++//
++++++++++++//+Fire+the+start+up+event+which+then+will+call+our+"StartUPRoutine"+below.
++++++++++++StartUpEvent();
++++++++}
++++++++//
++++++++//+Always+call+base+methods+unless+overriding+the+entire+fucntion
++++++++base.OnPaint(e);
++++}
++++#endregion


++++#region+"Your+StartUp+event+Entry+point"
++++//
++++//+Begin+executuing+your+code+here+to+validate+properties+etc.+and+to+run+your+program.+Enjoy!
++++//+Entry+point+is+just+following+the+very+first+WM_Paint+message+-+an+ideal+starting+place+following+form+load
++++void+StartUPRoutine()
++++{
++++++++//+Replace+the+initialized+text+with+the+following
++++++++this.Text+=+"Your+Code+has+executed+after+the+form's+load+event";
++++++++//
++++++++//+Anyway+this+is+the+momment+when+the+form+is+fully+loaded+and+ready+to+go+-+you+can+also+use+these+methods+for+your+classes+to+synchronize+excecution+using+easy+modifications+yet+here+is+a+good+starting+point.+
++++++++//+Option:+Set+FormReady+to+your+controls+manulaly+ie.+CustomControl.FormReady+=+true;+or+subscribe+to+the+StartUpEvent+event+inside+your+class+and+use+that+as+your+entry+point+for+validating+and+unleashing+its+code.
++++++++//
++++++++//+Many+options:+The+rest+is+up+to+you!
++++}
++++#endregion

}|1497391|}|1497392|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|Y|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|10|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

This an old question and depends more upon when you need to start your routines. Since no one wants a null reference exception it is always best to check for null first then use as needed; that alone may save you a lot of grief.

The most common reason for this type of question is when a container or custom control type attempts to access properties initialized outside of a custom class where those properties have not yet been initialized thus potentially causing null values to populate and can even cause a null reference exceptions on object types. It means your class is running before it is fully initialized - before you have finished setting your properties etc. Another possible reason for this type of question is when to perform custom graphics.

To best answer the question about when to start executing code following the form load event is to monitor the WM_Paint message or hook directly in to the paint event itself. Why? The paint event only fires when all modules have fully loaded with respect to your form load event. Note: This.visible == true is not always true when it is set true so it is not used at all for this purpose except to hide a form.

The following is a complete example of how to start executing you code following the form load event. It is recommended that you do not unnecessarily tie up the paint message loop so we'll create an event that will start executing your code outside that loop.

<pre><code>using System.Windows.Forms;
</code></pre>

namespace MyProgramStartingPlaceExample
{

<pre><code>/// &lt;summary&gt;
/// Main UI form object
/// &lt;/summary&gt;
public class Form1 : Form
{

 /// &lt;summary&gt;
 /// Main form load event handler
 /// &lt;/summary&gt;
 public Form1()
 {
 // Initialize ONLY. Setup your controls and form parameters here. Custom controls should wait for "FormReady" before starting up too.
 this.Text = "My Program title before form loaded";
 // Size need to see text. lol
 this.Width = 420;

 // Setup the sub or fucntion that will handle your "start up" routine
 this.StartUpEvent += StartUPRoutine;

 // Optional: Custom control simulation startup sequence:
 // Define your class or control in variable. ie. var MyControlClass new CustomControl;
 // Setup your parameters only. ie. CustomControl.size = new size(420, 966); Do not validate during initialization wait until "FormReady" is set to avoid possible null values etc. 
 // Inside your control or class have a property and assign it as bool FormReady - do not validate anything until it is true and you'll be good! 
 }

 /// &lt;summary&gt;
 /// The main entry point for the application which sets security permissions when set.
 /// &lt;/summary&gt;
 static void Main()
 {
 Application.EnableVisualStyles();
 Application.SetCompatibleTextRenderingDefault(false);
 Application.Run(new Form1());
 }


 #region "WM_Paint event hooking with StartUpEvent" 
 //
 // Create a delegate for our "StartUpEvent"
 public delegate void StartUpHandler();
 //
 // Create our event handle "StartUpEvent"
 public event StartUpHandler StartUpEvent;
 //
 // Our FormReady will only be set once just he way we intendded
 // Since it is a global variable we can poll it else where as well to determine if we should begin code execution !!
 bool FormReady;
 //
 // The WM_Paint message handler: Used mostly to paint nice things to controls and screen
 protected override void OnPaint(PaintEventArgs e)
 {
 // Check if Form is ready for our code ?
 if (FormReady == false) // Place a break point here to see the initialized version of the title on the form window
 {
 // We only want this to occur once for our purpose here.
 FormReady = true;
 //
 // Fire the start up event which then will call our "StartUPRoutine" below.
 StartUpEvent();
 }
 //
 // Always call base methods unless overriding the entire fucntion
 base.OnPaint(e);
 }
 #endregion


 #region "Your StartUp event Entry point"
 //
 // Begin executuing your code here to validate properties etc. and to run your program. Enjoy!
 // Entry point is just following the very first WM_Paint message - an ideal starting place following form load
 void StartUPRoutine()
 {
 // Replace the initialized text with the following
 this.Text = "Your Code has executed after the form's load event";
 //
 // Anyway this is the momment when the form is fully loaded and ready to go - you can also use these methods for your classes to synchronize excecution using easy modifications yet here is a good starting point. 
 // Option: Set FormReady to your controls manulaly ie. CustomControl.FormReady = true; or subscribe to the StartUpEvent event inside your class and use that as your entry point for validating and unleashing its code.
 //
 // Many options: The rest is up to you!
 }
 #endregion

}
</code></pre>

}

blocks|key|1712443|text|我知道这是一个古老的帖子。但我是这样做的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1712444|++++public+Form1(string+myFile)
++++{
++++++++InitializeComponent();
++++++++this.Show();
++++++++if+(myFile+!=+null)
++++++++{
++++++++++++OpenFile(myFile);
++++++++}
++++}

++++private+void+OpenFile(string+myFile+=+null)
++++{
++++++++++++MessageBox.Show(myFile);
++++}|code-block|syntax|javascript|1712445|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I know this is an old post. But here is how I have done it:

<pre><code> public Form1(string myFile)
 {
 InitializeComponent();
 this.Show();
 if (myFile != null)
 {
 OpenFile(myFile);
 }
 }

 private void OpenFile(string myFile = null)
 {
 MessageBox.Show(myFile);
 }
</code></pre>

blocks|key|1497474|text|以下是在之前的正确答案中添加的一些细节，特别是Matthias+Schippling的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1497475|在Form1_Load中添加一个事件处理程序，如下所示：|1497476|++private+void+Form1_Load(object+sender,+EventArgs+e)
++{
+++this.Shown+%2B=+new+EventHandler(Form1_Shown);
++}|code-block|syntax|javascript|1497477|接下来，添加将对代码执行某些操作的方法|1497478|++private+void+Form1_Shown(Object+sender,+EventArgs+e)
++{
+++draw_on_my_form_or_some_other_action();
++}|1497479|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Here are some details added to previous correct answers, especially the one by Matthias Schippling.
Add an event handler in Form1_Load, like this:
<pre><code> private void Form1_Load(object sender, EventArgs e)
 {
 this.Shown += new EventHandler(Form1_Shown);
 }
</code></pre>
Next, add the method that will do something with the code
<pre><code> private void Form1_Shown(Object sender, EventArgs e)
 {
 draw_on_my_form_or_some_other_action();
 }
</code></pre>

blocks|key|1497273|text|您可以在执行一些操作后关闭表单。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1497274|//YourForm.ActiveForm.Close()；|1497275|++++LoadingForm.ActiveForm.Close();|code-block|syntax|javascript|1497276|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can close your form after some execution..

//YourForm.ActiveForm.Close();

<pre><code> LoadingForm.ActiveForm.Close();
</code></pre>

In .NET, Windows Forms have an event that fires before the Form is loaded (Form.Load), but there is no corresponding event that is fired AFTER the form has loaded. I would like to execute some logic after the form has loaded.

Can anyone advise on a solution?

How do I execute code AFTER a form has loaded?

Windows

容器

在.NET中，Windows Forms有一个在加载窗体之前激发的事件(Form.Load)，但在窗体加载之后没有相应的事件激发。我想在表单加载后执行一些逻辑。有人能给出解决方案的建议吗？

问如何在加载窗体后执行代码？
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回答 8

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