I have a simple Windows Form with a button and textbox. I want the textbox to update with some string when the button is pressed. I know the following works:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
textBox1.text = "some string";
}
}
I also know, that the following will work. This gives me a bit more freedom, cause I can easily decide what I want to appear in the textbox:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
updateText("some string");
}
public void updateText(string s)
{
textBox1.Text = s;
}
}
Now, let's say that my code is getting big, and I want to keep things tidy. I want to move my code that performs updates into a different class called Updates. In that class I want to have a method that I can run on any textBox with any string. When I try the following, I get an error: The name 'textBox1' does not exist in the current context.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Updates.updateText("some string");
}
}
public class Updates
{
public void updateText(string s)
{
textBox1.Text = s;
}
}
I have seen more complex questions here about similar things, but I can't get their solutions to work. I think I'm missing something basic.
Additionally, I don't know how I would expand this method to accept any textBox, e.g.:
public void updateText(??? target, string s)
{
target.Text = s;
}
What type would target take?
Change your function to accept TextBox like this:
public void updateText(TextBox target, string s)
{
target.Text = s;
}
Samvel Petrosov answer is best solution, but if you would like to have another option, there it is: set the text box modifier to public (or internal), add reference to your form in Updates class. Then you will be able to modify it (text box) freely.
Related
I am learning C# and have run into an interesting issue to me. I have a class variable defined as public and I instantiate a new instance of my form in my class and access the value of the public variable it is always null.
To further explain my issue - this syntax prints the appropriate value
System.Diagnostics.Debug.WriteLine(tboxvalue.ToString());
However, this syntax is always outputting a 0
System.Diagnostics.Debug.WriteLine(f1.tboxvalue.ToString());
How do I need to alter my syntax so that the correct value is passed to the class Functions?
public partial class Form1 : Form
{
public double tboxvalue;
private string exportdata;
public Form1()
{
InitializeComponent();
}
private void btnClicker_Click(object sender, EventArgs e)
{
Functions.EE();
}
private void txtData_CheckedChanged(object sender, EventArgs e)
{
bool #checked = ((CheckBox)sender).Checked;
if (#checked.ToString() == "True")
{
exportdata = "Yes";
tboxvalue = Convert.ToDouble(this.txtData.Text);
System.Diagnostics.Debug.WriteLine(tboxvalue.ToString());
}
else
exportdata = "No";
}
}
class Functions
{
public static void EE()
{
Form1 f1 = new Form1();
System.Diagnostics.Debug.WriteLine(f1.tboxvalue.ToString());
}
}
To access properties of the form, you need to change two Things. First you have to pass the form to the 'EE' method, then you can access the form's properties. Second, don't create a new form in 'EE' method.
public partial class Form1 : Form
{
public double tboxvalue;
private string exportdata;
public Form1()
{
InitializeComponent();
}
private void btnClicker_Click(object sender, EventArgs e)
{
Functions.EE(this);
}
private void txtData_CheckedChanged(object sender, EventArgs e)
{
bool #checked = ((CheckBox)sender).Checked;
if (#checked.ToString() == "True")
{
exportdata = "Yes";
tboxvalue = Convert.ToDouble(this.txtData.Text);
System.Diagnostics.Debug.WriteLine(tboxvalue.ToString());
}
else
exportdata = "No";
}
}
class Functions
{
public static void EE(Form1 f1)
{
System.Diagnostics.Debug.WriteLine(f1.tboxvalue.ToString());
}
}
If i understood your question i guess you are recreated Form1 with own textbox or labels when you click btnClicker button. You can reassign your form objects where you created it.
You might add static Form1 object and Setter routine to Functions class:
private static Form1 _form;
public static void SetForm(Form1 form)
{
_form = form;
}
and pass the form to the class in Form_Load event-click on the form twice:
private void Form1_Load(object sender, EventArgs e)
{
Functions.SetForm(this);
}
Then you can play with the form in Functions class using the object _form
good luck!
For a project I am trying to change the text of a RichTextBox using a method from a different class. However when trying to pass a string through, it doesn't change the text but when I write Console.Writeline, it does show up.
What I think the problem is, is that I have to refresh the WindowsForm before the text can change.
namespace RichTextBox
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
addText.returnText();
}
public void addData(string s)
{
richTextBox1.AppendText(s);
Console.WriteLine(s);
}
}
}
And the other class:
namespace RichTextBox
{
class addText
{
public static void returnText()
{
string s = "test test;";
Form1 f = new Form1();
f.addData(s);
}
}
}
Try debugging your code and you'll see that the text of the RichTextBox in the addText class is set. Only... it is another instance of Form1 and not your current shown form. Add following line in the returnText method to see this:
f.Show();
Pass the form as a parameter to the class and then this will work. In the button click event, change the line to following:
addText.returnText(this);
And the returnText method looks like this:
public static void returnText(Form1 form)
{
string s = "test test;";
form.addData(s);
}
But better would be to return a value from the class and set that value in the richtextbox in the form class:
private void button1_Click(object sender, EventArgs e)
{
richTextBox1.AppendText(addText.returnText());
// OR
addData(addText.returnText());
}
public static string returnText()
{
string s = "test test;";
return s;
}
your returnText method is creating a new Form1, it shouldn't. There are a few options here, you could update the signature to expect a Form1 instance - returnText(Form1 f) and pass the current form instance to the method ( addText.returnText(this);
Or, and preferably, have the returnText method do exactly what it says - return the text, the calling code can update the rich text box. It keeps the responsibilities separate and clearer.
public static string returnText()
{
string s = "test test;";
return s;
}
calling code:
private void button1_Click(object sender, EventArgs e)
{
var s = addText.returnText();
addData(s);
}
I have seen a few links on attempts at this but I haven't found a solution. I am attempting to access my form textbox and update it with text from another class. I can update the text within my DataOrganizerForm class directly but when I pass text back to the DataOrganizerForm class then it doesn't update on the GUI. Here is what I have:
public partial class DataOrganizerForm : Form
{
//Default constructor
public DataOrganizerForm()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
//Handle a Start/Stop button click
private void start_stop_button_Click(object sender, EventArgs e)
{
SerialNumberSearcher snsearch = new SerialNumberSearcher();
snsearch.searchSN();
}
//Allow simple access to update to notification textbox
public void setNotificationText(string text)
{
notification_textbox.Text = text;
}
}
public class SerialNumberSearcher
{
public void searchSN()
{
DataOrganizerForm formAccess = new DataOrganizerForm();
formAccess.setNotificationText("Updated text from different class");
}
}
Well, it won't update the textbox 'cause you're instantiating another object of the DataOrganizerForm class. What you could do is passing a reference of the form object to the SerialNumberSearcher, like this:
public class SerialNumberSearcher
{
private readonly DataOrganizerForm _form;
public SerialNumberSearcher(DataOrganizerForm form)
{
_form = form;
}
public void searchSN()
{
_form.setNotificationText("Updated text from different class");
}
}
You need to understand at which instance you operate. When you use the new-eperator you create a new instance, like a new copy of that type.
DataOrganizerForm formAccess = new DataOrganizerForm();
The original Form is a different instance then the one you create in the searchSN method.
You need to pass that instance into the method to manipulate it:
public void searchSN(DataOrganizerForm formAccess )
{
formAccess.setNotificationText("Updated text from different class");
}
When you want to call this method you need to use this to reference the current object :
private void start_stop_button_Click(object sender, EventArgs e)
{
SerialNumberSearcher snsearch = new SerialNumberSearcher();
snsearch.searchSN(this);
}
this will access the current instance of the Form, thereby allowing you to manipulate the textbox that you are interested in.
When do you use the “this” keyword? might also be helpfull
Thanks for the help. This is what I was able to do to make my application work. I passed the Textbox object by reference to my other class and was able to display my information that way. Also, I had issues getting my text box to continuously update. I had to add
public partial class DataOrganizerForm : Form
{
//Default constructor
public DataOrganizerForm()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
//Handle a Start/Stop button click
private void start_stop_button_Click(object sender, EventArgs e)
{
SerialNumberSearcher snsearch = new SerialNumberSearcher();
snsearch.searchSN(notification_textbox);
}
//Allow simple access to update to notification textbox
public void setNotificationText(string text)
{
notification_textbox.Text = text;
notification_textbox.Update();
}
}
public class SerialNumberSearcher
{
public void searchSN(Textbox notifyTextbox)
{
notifyTextbox.setNotificationText = "Updated text from different class";
notifyTextbox.Update();
}
}
Still in the process of learning C#, but I'm a bit confused on something here.
For example, I have a textbox on my form and it has the name of testTXT. Based on the code below, I've created a new class outside of the public partial one that's there by default, and now I'm trying to access testTXT but I cannot. I'm going to also need to access several other textboxes and things later on as well.
Here's a snippet of the code I'm working with thus far:
namespace Test
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void testButton_Click(object sender, EventArgs e)
{
GeneratedClass gc = new GeneratedClass();
gc.CreatePackage("C:\\Users\\user\\Downloads\\output.docx");
}
private void browseButton_Click(object sender, EventArgs e)
{
var fsd = new FolderSelect.FolderSelectDialog();
fsd.Title = "Select folder to save document";
fsd.InitialDirectory = #"c:\";
if (fsd.ShowDialog(IntPtr.Zero))
{
testTXT.Text = fsd.FileName;
}
}
}
public class GeneratedClass
{
**trying to access testTXT right here, but can't.**
}
}
Any help would be greatly appreciated.
You could do this (see other answers), but you really shouldn't.
Nobody but the containing form has to know about the textboxes in it. Who knows, they might disappear, have their name changed, etc. And your GeneratedClass could become a utility class used by lots of forms.
The appropriate way of doing this, is to pass whatever you need from your textbox to your class, like so:
private void testButton_Click(object sender, EventArgs e)
{
GeneratedClass gc = new GeneratedClass();
gc.CreatePackage(this.testTxt.Text);
}
public class GeneratedClass
{
public void CreatePackage(string name) { // DoStuff! }
}
This is because you have your TextBox type defined in Form1 class as private member. Thus can't be access with another class instance
Your question has little to do with C#, more to do with Object Oriented Concepts.
Instance of TextBox has to be given to 'GeneratedClass' somehow.
namespace Test
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void testButton_Click(object sender, EventArgs e)
{
GeneratedClass gc = new GeneratedClass(testTXT);
gc.DoSomething();
gc.CreatePackage("C:\\Users\\user\\Downloads\\output.docx");
}
private void browseButton_Click(object sender, EventArgs e)
{
var fsd = new FolderSelect.FolderSelectDialog();
fsd.Title = "Select folder to save document";
fsd.InitialDirectory = #"c:\";
if (fsd.ShowDialog(IntPtr.Zero))
{
testTXT.Text = fsd.FileName;
}
}
}
public class GeneratedClass
{
TextBox _txt;
public GeneratedClass(TextBox txt)
{
_txt= txt;
}
public void DoSomething()
{
txt.Text = "Changed the text";
}
}
}
You must make testTXT public.
See Protection level (Modifiers) of controls change automaticlly in .Net.
And access to TextBox as
public class GeneratedClass
{
GeneratedClass(Form1 form)
{
form.testTXT.Text = "1";
}
}
I have Main Form which contains a Panel which loads different Usercontrol into the panel.
Now i need to access functions in the Main Form from the UserControl.
Below i have given my code;
This is my main Windows form class:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
loadlogin();
}
private void loadlogin()
{
login log = new login();
mainPannel.Controls.Clear();
mainPannel.Controls.Add(log);
}
public void mytest()
{
}
}
As you can see i am loading a usercontrol to the mainPannel.
Now lets look at the usercontrol:
public partial class login : UserControl
{
string MyConString = "";
public login()
{
InitializeComponent();
}
public void button1_Click_1(object sender, EventArgs e)
{
//I want to call the parent function mytest(); HOW????
}
}
I want to access mytest() function when button1 us clicked. I have tried alot of other solution but i am still confused.
I have used:
Form my = this.FindForm();
my.Text = "asdasfasf";
This gives me reference to parent and i can change the form text but how can i access its functions???
Ok, the above answer will work but it is not good coding practice to pass in a "Parent Form" to a user control. UserControls should be located in a separate project from your forms project and your forms project should reference your control project in order to gain visiblity to them. Lets say for instance that you want this UserControl to be nested in another UserControl at some point. Your code no longer works without overloading the constructor. The better solution would be to use an event. I have provided an implementation using a CustomEventArg. By doing this, your login UserControl can sit on anything and still work. If the functionality to change the parents text is not requried, simply do not register with the event. Here is the code, hope this helps someone.
Here is the form code:
public Form1()
{
InitializeComponent();
loadlogin();
}
private void loadlogin()
{
login log = new login();
//Registers the UserControl event
log.changeParentTextWithCustomEvent += new EventHandler<TextChangedEventArgs>(log_changeParentTextWithCustomEvent);
mainPannel.Controls.Clear();
mainPannel.Controls.Add(log);
}
private void log_changeParentTextWithCustomEvent(object sender, TextChangedEventArgs e)
{
this.Text = e.Text;
}
Here is the "login" UserControl code (in my test solution, just a userControl with a button)
public partial class login : UserControl
{
//Declare Event with CustomArgs
public event EventHandler<TextChangedEventArgs> changeParentTextWithCustomEvent;
private String customEventText = "Custom Events FTW!!!";
public login()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
//Check to see if the event is registered...
//If not then do not fire event
if (changeParentTextWithCustomEvent != null)
{
changeParentTextWithCustomEvent(sender, new TextChangedEventArgs(customEventText));
}
}
}
And finally, the CustomEventArgs class:
public class TextChangedEventArgs : EventArgs
{
private String text;
//Did not implement a "Set" so that the only way to give it the Text value is in the constructor
public String Text
{
get { return text; }
}
public TextChangedEventArgs(String theText)
: base()
{
text = theText;
}
}
Writing your controls in this fashion, with no visibility to Forms will allow your UserControls to be completely reusable and not bound to any type or kind of parent. Simply define the behaviors a UserControl can trigger and register them when necessary. I know this is an old post but hopefully this will help someone write better UserControls.
This may helps:
public partial class Form1 : Form
{
//Other codes
private void loadlogin()
{
login log = new login(this); //CHANGE HERE
mainPannel.Controls.Clear();
mainPannel.Controls.Add(log);
}
//Other codes
}
And
public partial class login : UserControl
{
Form1 _parent; //ADD THIS
public login(Form1 parent)
{
InitializeComponent();
this._parent = parent; //ADD THIS
}
public void button1_Click_1(object sender, EventArgs e)
{
this._parent.mytest(); //CALL WHAT YOU WANT
}
}
From your UserControl:
((Form1)Parent).mytest();