I have multiple constructors and I would like to to call one constructor that have parameters , how can I do that?
My UserControl :
public UserControl1()
{
InitializeComponent();
}
public UserControl1(string name)
{
InitializeComponent();
Console.WriteLine(name);
textbox1.Text = name;
}
App.xaml.cs
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
UserControl1 us = new UserControl1("John");
}
}
I made a breakpoints on UserControl1 construct that contains parameters and I saw that the the App startup called the constructor with parameters and than return to the other default constructor.
What's the reason?
Firstly, did you check app.xaml file because there is probably xaml code which tries to open and show UserControl1 like:
StartupUri="UserControl1.xaml"
If that case, you need to delete it and show UserControl1 in OnStartup function.
Secondly, are you sure that there isn't any other UserControl1 in your project? If there is, have you ever tried to use namespace? Like:
SolutionName.ProjectName.UserControl1 us = new SolutionName.ProjectName.UserControl1("John");
Thirdly, does the program read textbox1.Text = name; line then goes to default constructor section to read? Could you please give more detail about it and your namespaces?
Related
I am struggling with passing a Variable (a string) in C# for a special problem:
Overview:
I am writing a plugin for a purchased program at my company. The program (or better: the programs support) gives the user basic C#-Code which basically just opens a form, and connects the program with whatever I write down in the forms code.
As it is a Visual-Studio-Solution I get some files: "MyUserInterface.cs" and "MyUserInterface.Designer.cs".
"MyUserInterface.Designer.cs" defines the look of my form, i thing the most importand parts for my problem are:
partial class MyUserInterface
{
[...]
private void InitializeComponent()
{
[...]
this.f_status = new System.Windows.Forms.Label();
this.SuspendLayout();
[...]
//
// status
//
this.f_status.Name = "status";
this.f_status.Text = "WELCOME TO MYPLUGIN v2";
[...]
this.Controls.Add(this.f_status);
this.ResumeLayout(false);
this.PerformLayout();
}
[...]
private System.Windows.Forms.Label f_status;
[...]
}
The most important code from "MyUserInterface.cs" is:
partial class MyUserInterface
{
[...]
public MyUserInterface()
{
InitializeComponent();
}
[...]
private void click_compute(object sender, EventArgs e)
{
//Basically everythings runs here!
//The code is opend in other classes and other files
}
}
Now as i marked in the code section, my whole code runs in the "click-compute" Function and is "outsourced" into other classes.
One important part of my code is found in "statushandler.cs":
class statushandler
{
[...]
public static void status_msg(string c_msg)
{
[...]
f_status.Text = c_msg; // And here is my problem!!
[...]
}
}
Problem:
In my special case, i try to change the text of the "f_status"-Lable while running my code by using the "status_msg" Function!
While I pass variables between classes a few times in my code. A cannot figure out, why this explicit one cant be found inside "statushandler". (It is no problem as long as I stay inside the original "click_compute", without going into a different class).
What I already tried:
1.) I tried to change basically everything in "MyUserInterface" into "public",
2.) Also I tried to call f_status in status_msg like MyUserInterface.f_status.Text,
3.) Write a Getter/Setter-Function in "MyUserInterface.(Designer.)cs" (both), which was catastrophic because i couldn't define the Label in the InitializeComponent anymore.
4.)
a.)Read a lot of Stackoverflow-Threads about passing variables between classes, which all didn't helped, all solutions I found, are working between classes, but not in this special case.
b.)Watched a lot of youTube tutorials, same result.
c.)Read some stackoverflow-Threds about passing variables between different Forms, but they all had in common, that the "displaying-form" was opend AFTER the variable was known. In my special case the form is opened all the time, and can't be closed, nor reopened...
And now I am out of ideas!
I wouldn't be surprised, if I do not see some details, but I can't found them... I would be very happy, when somebody could help me!
My question:
How can I change the text of my lable from another class?
Your method is static while your form has instance. So your static method does not know anything about your form. You can add MyUserInterface parameter to static method
public static void status_msg(MyUserInterface form, string c_msg)
{
[...]
form.f_status.Text = c_msg; // And here is my problem!!
[...]
}
If you have single instance form (only one instance is created at a time) you can have static property with it's reference:
partial class MyUserInterface
{
public static MyUserInterface Instance { get; private set; }
[...]
public MyUserInterface()
{
InitializeComponent();
Instance = this;
}
}
With this solution you can use your old method:
class statushandler
{
[...]
public static void status_msg(string c_msg)
{
[...]
MyUserInterface.Instance.f_status.Text = c_msg; // You have instance of yout form here
[...]
}
}
Of course you should protect against null/ Disposed form etc.
Create a public property on the specific class in your 1st Form that gets the label's value like this:
public string Name {get {return Label1.Text}; set {Label1.Text = value}; }
Then in your 2nd Form:
public Form2(Form1 form)
{
string name;
name = form.Name;
}
I was wondering how you would close the Form that is currently in focus or the one which a control is contained in. For example, I have an imported header with a menu that I import into all forms in my application.
This is the (simplified) code in my Header class:
public static Panel GetHeader()
{
...
menuItem.Text = "Menu Item";
menuItem.Name = "Next form to open";
menuItem.Click += toolStrip_Click;
...
}
public static void toolStrip_Click(object sender, EventArgs e)
{
ToolStripMenuItem menuItem = sender as ToolStripMenuItem;
NavigationClass.SaveNextForm(menuItem.Name);
}
The navigation class is just something I made which will select the next form to open but I couldn't find anything to then close the current one (since Close() isn't an option due to it being imported with Controls.Add(HeaderClass.GetHeader))
Edit
Just to make clear, this form is in another file which is just a normal class file. That's where the difficulty lies because I'm trying to avoid a severe violation of the DRY principle
Don't use static handlers as #Hans Passant suggests. That is important.
Try sending your main form to your class as a parameter, and store it in that class. This can be done either when you are instantiating your class, or after that. Then, when you need to close the form, call it's Close method. Since you don't include your codes in more details, here is my example with some assumptions.
public class MainForm : Form
{
private HeaderClass HeaderClass;
public MainForm()
{
HeaderClass = new HeaderClass(this);
}
}
public class HeaderClass
{
private MainForm MainForm;
public HeaderClass(MainForm mainForm)
{
MainForm = mainForm;
}
public void MethodThatYouNeedToCloseTheFormFrom()
{
...
MainForm.Close();
...
}
}
Let us know if you require any more elaboration.
Let's say in a WPF project I've built an abstract window class so I can add some base properties to every window I create derived from that:
// Abstract window, based on normal window
public abstract partial class abs_window : Window
{
// example of added property to my abstract class
protected int xxx = 25;
public abs_window()
{
InitializeComponent();
}
}
// Another class dervied from my abstract window
public partial class derivedWindow : abs_window
{
void aa()
{
// Random method aa() to show access to the protected xxx int
MessageBox.Show(Convert.ToString(xxx));
}
}
So, this compiles fine, but my StartUpUri is pointing to the default MainWindow that I don't really want at all... I want it to point straight to a new instance of my doubly derived derivedWindow class? Is that possible?
I tried both
StartupUri="abs_window.xaml" and StartupUri="derivedWindow.xaml"> but the first couldn't work since it's abstract and the 2nd doesn't work because there isn't an existing .xaml file
If I add a new "window" .xaml file it'll just be a normal window and not my derived type!?
Answering on behalf of Hans' comment unless he chooses to answer also:
First created a startup method in the default App class (App.xaml.cs) like Hans' link here
public partial class App : Application
{
void App_Startup(object sender, StartupEventArgs e)
{
derivedWindow window = new derivedWindow();
window.Show();
}
}
But what that link didn't mention was to change the App.xaml file by replacing a StartupUri which seems to be always referencing an .xaml with a Startup method StartupUri="MainWindow" with Startup="App_Startup" which I found here
For example after creating a new Windows Form project I have my class called Form1.cs and from that form I can simply start typing the name of a form control and it will auto populate the form control variable names and I am able to use them in the class. However I have other classes that need to be able to access these form control variables as well, but they are not accessible.
Make them public if they are going to be used in another assembly, or internal if they are going to be used in the same project. Making them static means you don't have to pass your Form1 into the other classes.
Example... Say your Form1 has a string that contains the text you display in the title bar. Making it internal static, like this:
internal static readonly string MsgBox_Title = " Best Application Evar!";
lets you access it from other classes like this:
Form1.MsgBox_Title
It doesn't have to be readonly; that's just an example I pulled from an old app...
If you don't want static variables, you'll have to pass in an instance of Form1.
public class SomeClass
{
private Form1 m_Form1;
public SomeClass(Form1 form1)
{
m_Form1 = form1;
}
private void someMethod()
{
string localValue = m_Form1.SomeMemberStringVariable;
}
}
It's a very contrived example, but hopefully you get the idea.
If you want to call the Refresh method from a class instantiated from Form1, you could use an event in the child class to notify Form1.
Example:
This Form1 has a button that I use to show a secondary form.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void btnShowPopup_Click(object sender, EventArgs e)
{
PopupForm f = new PopupForm();
f.CallRefreshHandler += PopupForm_CallRefreshHandler;
f.ShowDialog();
}
private void PopupForm_CallRefreshHandler(object sender, EventArgs e)
{
Refresh();
}
}
The secondary form, "PopupForm", has a button that I use to raise an event that the Form1 is subscribed to, and lets Form1 know to call Refresh.
public partial class PopupForm : Form
{
public event EventHandler CallRefreshHandler;
public PopupForm()
{
InitializeComponent();
}
private void btnRaiseEvent_Click(object sender, EventArgs e)
{
EventHandler handler = CallRefreshHandler;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
}
}
Hope this helps.
Create an object of that class & start using those variables like this
Form1 fm = new Form1();
string abc = fm.VAR;
Define a public property in your form.
public string MyProp { get; set; }
Form1 frm = new Form1();
frm.MyProp = "Value";
Or define the property as static to avoid having to instantiate Form1:
public static string MyProp { get; set; }
Form1.MyProp = "Value";
I ran into this issue recently. I was keeping some methods in a separate class. Maybe not a good design decision in my case, I'm not sure yet. And these methods sometimes needed to communicate with controls in the main Form1. For example, to write to textBox1.
Turns out easy enough. Just write your method signature to include a TextBox instance. For example you pass textBox1 in and inside the method you refer to it as tb. Then when you call that method (even though it is in another class) you set the tb.Text property to whatever you like and it will show on textBox1.
This makes sense when you consider that control is just a special kind of object, graphically represented in the Form. When you pass it as an argument to a method in another class or the same class, you are actually passing the reference. So writing text to it in the method call will write text to the original control.
I'm wondering if it is possible to access a textbox value from another class inside a C# winform.
For example, at the moment I have a bunch of different textboxes I'm turning on and off all within my Form1.cs class like so:
screentextBox.Visible = true;
However, to cut down on the amount of lines of code within my C# class I was wondering is it possible to make this call from another class, then in my Form1.cs call my other classes method?
Something like:
class Otherclass
{
public void ShowTextBox()
{
screentextBox.Visible = true;
}
}
Then in my Form1.cs simply call my new ShowTextBox method.
I'm sorry if this is a silly question, but I've looked around google and I couldn't find anything that could help me out.
You could pass the TextBox as a parameter to a function in another class:
class OtherClass
{
public void ShowTextBox(TextBox target)
{
target.Visible = true;
}
}
However, I would advise to keep all the methods and code pertaining to handling the GUI and its events inside the form itself. If you have large methods for calculations, etc., than those can be moved to other classes.
you can Make ScreentextBox as Public in Declaring class and access it in Another class like
class Otherclass
{
public void ShowTextBox()
{
Class1.ScreenTextBox.Visible =true;
}
}
You could define the ShowTextBox method in a partial class So you still have the access to the control and also tidy your code.
Add method for showing TextBox in your form:
public partial class Form1 : Form
{
public void ShowTextBox()
{
screentextBox.Visible = true;
}
}
and then pass your From1 to other forms and call this method from there.
Class OtherClass
{
public static void method(TextBox[] items)
{
foreach(item in items)
{
(item as TextBox).Visible = true;
}
}
}
to call this method from ur Form1.cs class--->
OtherClass.method( new TextBox[] { TxtBox1, TxtBox2, TxtBox3 } );
If you want to access the controls of Form1.cs from another class try this way
class Otherclass
{
Form1 f1 = new Form1();
f1.Controls["screentextBox"].Visible = true;
}
I would do it like this (example from John Willemse):
class OtherClass
{
public TextBox ShowTextBox(TextBox target)
{
target.Visible = true;
return target;
}
}
Yet another approach to this old problem: I've found that the old way is an easy way to make accessible controls (including all their properties and methods), and perhaps other variables, from any class within the project. This old way consists of creating an ad hoc class from scratch.
Note A: about the old way: I know, I know, global variables are evil. But, for many people coming here looking for a fast/flexible/suites-most-cases solution, this may be a valid answer and I have not seen it posted. Another thing: this solution is what I am actually using as the answer for what I came to this page looking for.
1st step: The new class file from scratch is below.
namespace YourProjectNamespace
{
public class dataGlobal
{
public System.Windows.Forms.TextBox txtConsole = null;
// Place here some other things you might want to use globally, e.g.:
public int auxInteger;
public string auxMessage;
public bool auxBinary;
// etc.
}
}
Note B: The class is not static nor has static members, which allows to create several instances in case it is needed. In my case I do take advantage of this feature. But, as a matter of fact, you may consider making this class' TextBox a public static field so that -once initialized- it is always the same throughout the application.
2nd step: Then you're able to initialize it in your Main Form:
namespace YourProjectNamespace
{
public partial class Form1 : Form
{
// Declare
public static dataGlobal dataMain = new dataGlobal();
public Form1()
{
InitializeComponent();
// Initialize
dataMain.txtConsole = textBox1;
}
// Your own Form1 code goes on...
}
}
3rd step: And from your other class (or form), the call to any property/method of Form1's textBox1:
namespace YourProjectNamespace
{
class SomeOtherClass
{
// Declare and Assign
dataGlobal dataLocal = Form1.dataMain;
public void SomethingToDo()
{
dataLocal.txtConsole.Visible = true;
dataLocal.txtConsole.Text = "Typing some text into Form1's TextBox1" + "\r\n";
dataLocal.txtConsole.AppendText("Adding text to Form1's TextBox1" + "\r\n");
string retrieveTextBoxValue = dataLocal.txtConsole.Text;
// Your own code continues...
}
}
}
[EDIT]:
A simpler approach, specifically for the TextBox visibility throughout classes, I have not seen in other answers:
1st step: Declare and initialize an auxiliary TextBox object in your Main Form:
namespace YourProjectNamespace
{
public partial class Form1 : Form
{
// Declare
public static TextBox txtConsole;
public Form1()
{
InitializeComponent();
// Initialize
txtConsole = textBox1;
}
// Your own Form1 code goes on...
}
}
2nd step: And from your other class (or form), the call to any property/method of Form1's textBox1:
namespace YourProjectNamespace
{
class SomeOtherClass
{
public void SomethingToDo()
{
Form1.txtConsole.Visible = true;
Form1.txtConsole.Text = "Typing some text into Form1's TextBox1" + "\r\n";
Form1.txtConsole.AppendText("Adding text to Form1's TextBox1" + "\r\n");
string retrieveTextBoxValue = Form1.txtConsole.Text;
// Your own code continues...
}
}
}
Comment to the [Edit]: I have noticed that many questions simply cannot be solved by the usual recommendation: "instead, make public properties on your form to get/set the values you are interested in". Sometimes there would be several properties/methods to implement... But, then again, I know... best practices should prevail :)