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;
}
Related
I have two files, form1.cs and parser.cs. When I called my update method for NPCLogger.Text in the form1.cs file it works. but when I call it from parser.cs it does not? I've tried a lot of other solutions online and can't seem to get it working.
form1.cs
public void updateConsole(string text)
{
NPCLogger.Text += text;
}
private void ParseButton_Click(object sender, EventArgs e)
{
Parser parser = new Parser();
string link = UserLink.Text;
parser.Parsing(link);
updateConsole("12312"); // this works
}
parser.cs
public class Parser : Form
{
public bool debug = false;
public string aggroRadius = null;
public void Parsing(string userLink)
{
updateConsole("This does not work");
The compiler error you're seeing (but not including in the question...) is telling you that there is no updateConsole method in the Parser class. (Unless you've added one, and didn't include that in the question. In which case... what on Earth does that method do and why are you expecting a method on a different class to be invoked?)
When you attempt to call a method that's in the Parser class from the Form1 class, note how you do that:
parser.Parsing(link);
You don't just call Parsing(link) by itself, you call it on the parser variable, which is an instance of the Parser class. So, when you want to call a method that's in the Form1 class from the Parser class, why do you expect it to be any different?
You need a reference to your Form1 object. Given the code shown, probably the simplest way is to add it to the Parser constructor:
private Form1 form1Instance { get; set; }
public Parser(Form1 form1)
{
this.form1Instance = form1;
}
And pass the reference when calling the constructor:
Parser parser = new Parser(this);
Then, in Parser, you can use that property to reference the object:
this.form1Instance.updateConsole("This does not work");
As an aside... You're digging yourself into a rabbit hole. Now you have two forms trying to directly interact with each other's UI controls. It's going to get unwieldy quickly.
A form should be responsible for its own UI controls. Models/objects (not forms) should encapsulate the core logic of the application. Any given form would invoke that logic and use the returned result to update its UI.
I have one main form and a static class when i access static class member it gives me nullreference error . Previously it was working fine donot know what happend . Any one can suggest what is wrong.
code snap:
namespace MyNamespace
{
public partial class myForm : Form
{
public myForm()
{
InitializeComponent();
}
private void myForm_Load(object sender, EventArgs e)
{
My_Static_Data_Class.player_name="Demo Player"
}
}
public static class My_Static_Data_Class
{
public static string player_name = "";
}
}
please help?
You're either accessing the static class member before it was set to "Demo Player". For example, you are trying accessing My_Static_Data_Class.player_name in Program.cs code before it calls the main form from the Main[] method. Alternatively you're might be setting My_Static_Data_Class.player_name to null elsewhere in code and then accessing it.
Check all the references in code editor and follow it up. To do this, right click on My_Static_Data_Class.player_name in Visual Studio editor, and choose Find All References menu item.
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 :)
The case is this, I have two different forms from the same solution/project. What I need to do is to extract the value of a label in Form A and load it into Form B. As much as possible, I am staying away from using this code since it will only conflict my whole program:
FormB myForm = new FromB(label.Text);
myForm.ShowDialog();
What I am trying right now is a class with a property of get and set for the value I wanted to pass. However, whenever I access the get method from FormB, it returns a blank value.
I hope somebody can help me with this. Any other ways to do this is extremely appreciated. :)
public class Miscellaneous
{
string my_id;
public void SetID(string id)
{
my_id = id;
}
public string GetID()
{
return my_id;
}
}
You could do something like this:
Child form
public string YourText { get; set; }
public TestForm()
{
InitializeComponent();
}
public void UpdateValues()
{
someLabel.Text = YourText;
}
Initiate it
var child = new TestForm {YourText = someTextBox.Text};
child.UpdateValues();
child.ShowDialog();
With this approach you don't have to change the Constructor, you could also add another constructor.
The reason for them being empty is that the properties are set after the constructor, you could Also do someting like this to add a bit of logic to your getters and setters, However, I would consider not affecting UI on properties!
private string _yourText = string.Empty;
public string YourText
{
get
{
return _yourText;
}
set
{
_yourText = value;
UpdateValues();
}
}
In this case, the UI will be updated automaticly when you set the property.
You can use a static variable/method to hold/pass the value of a control (when it gets changed).
You can use form reference or control reference to get and pass values directly.
You can use custom event for that (notifying the code that subscribed).
btw. FormB myForm = new FromB(label.Text); did not work because you are passing by value and the value was empty at the moment of creation of FormB.
FormB myForm = new FromB(label); would have worked.
Well one approach to take is to create a singleton class in your application. When you form b loads or the label changes you update the singleton with the value. Then when form a needs the value it can just get the instance of the singleton within your application and it will have that value.
There are probably cleaner ways to do it but just thinking of an easy way to pass information back and forth and store any information needed for both forms.
EDIT: Here is an example of a singleton that I pulled from here:
http://www.yoda.arachsys.com/csharp/singleton.html
public sealed class Singleton
{
static readonly Singleton instance=new Singleton();
// Explicit static constructor to tell C# compiler
// not to mark type as beforefieldinit
static Singleton()
{
}
Singleton()
{
}
public static Singleton Instance
{
get
{
return instance;
}
}
}
Now all you need to do is put this class in a namespace that is accessible to both forms and then you can call the Instance property of this class and then reference your values. You can add properties to it as well for whatever you want to share. When you want to retrieve those values you would call it like this:
Singleton.Instance.YourProperty
((Form2)Application.OpenForms["Form2"]).textBox1.Text = "My Message";
declare public property varible in second form
Public property somevariable as sometype
and access it in first form using instance
Dim obj as New form2()
obj .somevariable ="value"
How can I make a textbox in my winforms application that accepts new lines of text from anywhere in the application?
I have a main form that contains a textbox. I'd like to directly add text to the box from a method in another class.
Update
I tried this in my main form:
public void Output(String value)
{
if (txtOutput.Text.Length > 0)
{
txtOutput.AppendText(Environment.NewLine);
}
txtOutput.AppendText(value);
}
But I can't call Output from the other class. I'm new to C#, so perhaps I'm missing something obvious.
Regards, Miel.
PS Yes, I know this is bad design, but for now this seems to be the best way to do what I want. The textbox would function like a console.
You'll need to expose the Text property of the TextBox as a string property on your form. For example...
public string TextBoxText
{
get { return textBoxName.Text; }
set { textBoxName.Text = value; }
}
Edit
After reading the question edit, your problem is that you need a reference to a specific instance of the form whereever you're trying to execute that code. You can either pass around a reference (which is the better option), or you could use some smelly code and have a static property that refers to one instance of your form. Something like...
public partial class MyForm : Form
{
private static MyForm instance;
public static MyForm Instance
{
get { return instance; }
}
public MyForm() : base()
{
InitializeComponent();
// ....
instance = this;
}
}
Using this approach, you could call MyForm.Instance.Output("test");
In order to decouple a bit more you could inverse the control a bit:
// interface for exposing append method
public interface IAppend
{
void AppendText(string text);
}
// some class that can use the IAppend interface
public class SomeOtherClass
{
private IAppend _appendTarget = null;
public SomeOtherClass(IAppend appendTarget)
{
_appendTarget = appendTarget;
}
private void AppendText(string text)
{
if (_appendTarget != null)
{
_appendTarget.AppendText(text);
}
}
public void MethodThatWillWantToAppendText()
{
// do some stuff
this.AppendText("I will add this.");
}
}
// implementation of IAppend in the form
void IAppend.AppendText(string text)
{
textBox1.AppendText(text);
}
It looks like your design is a little bit corrupted. You shouldn't let buisness logic mess with GUI controls. Why don't you try a return value and assigning it on the interface side?
This is a REALLY bad way of doing it, but just to make sure all the answers are out there...
In the VS designer, each form control has an item in the Properties window named Modifiers that defaults to Private. Changing this to one of the others settings, such as Internal or Public, will let you access it from outside the form.
I must stress that this is the worst way to do it.