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();
}
}
Related
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 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.
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";
}
}
My program has a main form where I keep a repository of values from other sub forms. For some reason the sub form is giving me an error:
an object reference is required for the non-static field
This is my main form:
public partial class frm_SystemLog : Form
{
public frm_SystemLog()
{
InitializeComponent();
}
public string TextBoxValue
{
// suppose to get value from other forms
get { return this.textBox1.Text; }
set { textBox1.Text = value; }
}
private void frm_SystemLog_Load(object sender, EventArgs e)
{
Log frm_LoginMenu = new Log();
frm_LoginMenu.ShowDialog();
}
}
This is my sub form:
public partial class Log : Form
{
public Log()
{
InitializeComponent();
}
private void button2_Click(object sender, EventArgs e)
{
// this is where the error happens
frm_SystemLog.TextBoxValue = "SomeValue";
this.Close();
}
}
you should create a property in your log form then set its value when you are accessing it
//in log form
public String MyValue{get;set;}
then in properties of your button2 of log form choose dialogresult and set it to ok
then in your button2 click event
private void button2_Click(object sender, EventArgs e)
{
MyValue = "SomeValue";
//no need to close ,dialogresult will do it...
}
then in your frm_SystemLog form do this
private void frm_SystemLog_Load(object sender, EventArgs e)
{
Log frm_LoginMenu = new Log();
frm_LoginMenu.ShowDialog();
if(frm_LoginMenu.ShowDialog() == DialogResult.OK)
{
this.TextBoxValue = frm_LoginMenu.MyValue;
}
}
this should solve your problem.
frm_SystemLog.TextBoxValue isn't accessible from button2_Click, because it's in a different class.
Currently you're trying to reference an object on your parent form class, not an instance of your class. In that case, the only objects you can reference are static ones, hence the error you're getting.
You need an actual reference to the instance of your parent form. Change your Log class as follows:
public partial class Log : Form
{
private frm_SystemLog parentForm;
public Log(frm_SystemLog parentForm)
{
InitializeComponent();
this.parentForm = parentForm;
}
...
...
Then instantiate your sub form using:
Log frm_LoginMenu = new Log(this);
Read "Understanding Classes, Methods, and Properties in C#" for more information, in particular:
There are two kinds of methods in C#. They are:
Instance Method
Static Method
Instance Methods are methods declared outside the main method and can be accessed only by creating an object of the corresponding class.
Class methods also are declared outside the main method but can be accessed without creating an object of the class. They should be declared with the keyword static and can be accessed using the classname.methodname syntax.
I apologize in advance with what will probably be a fairly easy/quick answer based on scope, but I've looked everywhere and am surprised to not come up with an answer.
I have created a class called Soldier with roughly 100 class variables. I need a user to enter information and gradually build a Solider object over the course of several different class Forms (because there is too much data to collect on just one).
I create an (empty) instance of a Soldier (tempSoldier) in Form1.cs and start to set the object's class variables that I collect from the user.
private void button1_Click(object sender, EventArgs e)
{
Soldier tempSoldier = new Soldier();
tempSoldier.surname = textbox1.text;
}
My question: how do I gain access to the object instance (tempSoldier) from Form1.cs in the other classes (Form2.cs, Form3.cs ...)?
I should mention that all of the Forms (Form1.cs, Form2.cs ...) share the same namespace.
Thanks in advance
Edit: All solutions below work so it just depends upon which one you like the best. Thank you for your feedback.
One little note, make sure you make ALL of the class modifiers Public including your custom class (in my case Soldier.cs).
You'll need to declare the Soldier instance in in a higher scope.
One way of doing this would be to declare it inside Form1, then pass it to Form2, and so on.
public class Form1
{
private Soldier tempSoldier = new Soldier();
private void button1_Click(object sender, EventArgs e)
{
tempSoldier = new Soldier();
tempSoldier.surname = textbox1.text;
}
private void GotoNextStep()
{
// pass the existing instance to the next form
Form2 form2 = new Form2(tempSoldier);
// display form 2 ...
}
}
Another possibility is to use a singleton variable in a class that all the forms have access to.
public class MyAppManager
{
private static readonly Soldier _soldier = new Solider();
public static Soldier SoldierInstance
{
get { return _soldier; }
}
}
private void button1_Click(object sender, EventArgs e)
{
MyAppManager.SoldierInstnace.surname = textbox1.text;
}
The former approach is ok if there's a distinct sequence to the forms; the latter is better if difference forms could be used at different times or revisited.
You can also make Soldier a static variable :
public static Soldier soldier {get;set;}
private void button1_Click(object sender, EventArgs e)
{
soldier = new Soldier();
soldier.surname = textbox1.text;
}
Code in other forms:
Form1.soldier.name ="";
You should create a public property on your form that exposes the soldier. You can then access this property from the other forms.
// ...
public Soldier Soldier { get; private set; }
private void button1_Click(object sender, EventArgs e)
{
Soldier tempSoldier = new Soldier();
tempSoldier.surname = textbox1.Text;
this.Soldier = tempSoldier;
}
// ...
Your Form2 class could look something like this:
public partial class Form2
{
private Form1 form1;
public Form2(Form1 form1)
{
this.form1 = form1;
this.InitializeComponent();
}
public void DoStuffWithForm1()
{
// ...
string surname = this.form1.Soldier.surname;
// ...
}
}
In your other class, create a method with objects as parameters.
public class TryMe (TextBox newTextbox) {
newTextbox.Text = "Hello this is a text."
//You can also get the value of textbox of another form
var textString = newTextbox.Text;
}
And then in your main form, call that method with your objects as parameters. In this case, add textbox1 to your method's parameter.
Your code in form:
TryMe(textbox1);