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 :)
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;
}
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.
im writing an application in visual studio and im trying to access a rich text box from an other class. This doesnt seem to work for me. Also how to i call a function from an other class?
My code:
namespace Test{
public partial class Form1 : Form
{
public Form1()
{
// I want from this place to access the MyClass.test("hello");
}
}
}
namespace Test{
class MyClass
{
public void test (string text)
{
// here i want to do richtextbox1.clear(); but the textbox is not available
}
}
}
can be done in many ways. My favorite would be to declare the object of the "MyClass" class within "Form1" by passing the "this" pointer as an argument. Thus, the object of the "MyClass" class will have access to all the members and public functions "Form1". Included RichTextBox1.
namespace Test{
public partial class Form1 : Form
{
MyClass MyClassObject;
public Form1()
{
InitializeComponent();
MyClassObject=new MyClass(this);
MyClassObject.test("hello");
}
}
}
namespace Test{
class MyClass
{
Form1 parent;
public MyClass(Form1 parentForm)
{
parent=parentForm;
}
public void test (string text)
{
parent.richtextbox1.clear();
}
}
}
You don't want to do this. You can for example do it like this:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
var myClass = new MyClass(this.richtextbox1);
myClass.SetTextBoxText("hello");
}
}
class MyClass
{
RichTextBox _textBox;
public MyClass(RichTextBox textBox)
{
_textBox = textBox;
}
public void SetTextBoxText(string text)
{
_textBox.Clear();
_textBox.Text = text;
}
}
This uses constructor injection to pass the textbox to operate on to the contstructor. In Form1's constructor the MyClass is instantiated with a reference to the textbox, which is initialized in InitializeComponent(). Then when you call SetTextBoxText, the class clears the associated textbox's text and then sets it to the passed text.
This is more specific than the commonly suggested method: just pass the entire Form1 instance to MyClass's constructor after making the textbox public, but that way you cannot reuse MyClass for other forms.
But as you see, it's pretty pointless to do. You can let Form1 contain this.richttextbox1.Text = "hello"; directly.
It is not quite clear from your question, but I'm supposing your richtextbox1 is located at Form1.
By default all UI elements of form has private acess modifier - that's why you can't access your richtextbox1 from outer class.
You can change it's access mmodifier to public - but I strongly encourage you not to do it.
Instead write some method in Form1 class like
public void ClearRichTextBox()
{
richtextbox1.Clear();
}
and use it.
This should be quite simple really - not sure what the problem is.
I have a C# Class (Public.cs) and a windows form (Form1.cs). Through a function in Public.cs, I want to get the value of a control on Form1 (without having to use object parameters).
// This code appears in Public.cs
public string MyFunction(int num_val)
{
if (chk_num.checked == true)
{
// Something here...
}
}
The issue is that my class cannot find the control on my form. Is there some way that I must reference it in C#?
Thank you.
I would strongly suggest exposing the Checked property via a specific property on Form1 (perhaps with a more meaningful name). This will help to hide the implementation details (i.e. control structure) of the Form1 from it's caller and instead expose only the logic that is required for other consumers to do their job
For example:
public bool IsNumberRequested
{
get { return chk_num.Checked; }
}
Or alternatively, if you still really want to access the control directly, from the designer you can select the control and change it's Modifier property to public (or something else) enabling you to access the control object using the code you originally wrote above.
EDIT: (Response based on comment)
Public.cs will still need a reference to Form1 and then will call the IsNumberRequested property of that object.
// Public.cs
public class Public
{
private Form1 _ui;
public Public(Form1 ui) { _ui = ui };
public string MyFunction(int num_val)
{
if (_ui.IsNumberRequested)
{
// Stuff
}
// Else, default Stuff
}
}
Alternatively, you could pass the form as a parameter to the MyFunction too rather than using it as an instance variable.
I would have the set up the other way around
public class Public
{
public bool CheckNumber {get;set;}
public string MyFunction(int val)
{
if(CheckNumber)
{
//do that thing
}
return ...
}
}
public partial class Form1 : Form
{
Public myinstance = new Public();
public Form1()
{
InitializeComponent();
}
private void CheckBoxChanged(object sender, EventArgs e)
{
myinstance.CheckNumber = chk_num.checked;
}
}
You'll need to assign CheckBoxChanged to the OnChanged event handler for your check box (which I'm assuming is chk_num.
This way your class Public doesn't rely on a form, which it shouldn't.
As Reddog says, use better names, although I half suspect you've just given example names in your question.
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.