I am trying to create an object of a class, but it doesn't seem to work, I can't help but think I am looking at this from a JAVA perspective:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
PortChecks PortCheckObject = new PortChecks();
}
private void testCheck_Click(object sender, EventArgs e)
{
PortCheckObject.MyMethod();
}
I can error when using the PortCheckObject to call my method MyMethod
(PortChecks is the class name)
It's because it's outside of the scope of testCheck_Click
public partial class Form1 : Form
{
PortChecks PortCheckObject = new PortChecks();
public Form1()
{
InitializeComponent();
}
private void testCheck_Click(object sender, EventArgs e)
{
PortCheckObject.MyMethod();
}
}
PortChecks PortCheckObject in Form1 constructor is a local variable.
Put its declaration as a private field in Form1 class.
public partial class Form1 : Form
{
private PortChecks PortCheckObject = new PortChecks();
public Form1()
{
InitializeComponent();
}
private void testCheck_Click(object sender, EventArgs e)
{
PortCheckObject.MyMethod();
}
}
#James,
You need a class property with the name 'PortCheckObject' and can be possible to access in other parts of the class.
public partial class Form1 : Form
{
private PortChecks PortCheckObject;
public Form1()
{
InitializeComponent();
PortCheckObject = new PortChecks();
}
private void testCheck_Click(object sender, EventArgs e)
{
PortCheckObject.MyMethod();
}
}
This is a general scope issue, not a Java v.s. C# issue (as your code wouldn't work in Java either). PortCheckObject is in Form1()'s scope, not testCheck_Click's scope. Try the following:
public partial class Form1 : Form
{
private PortChecks PortCheckObject;
public Form1()
{
InitializeComponent();
PortCheckObject = new PortChecks();
}
private void testCheck_Click(object sender, EventArgs e)
{
PortCheckObject.MyMethod();
}
This is an instance of a scope problem. You do not have scope in your testCheck_Click method. Make the following change and it should work:
public partial class Form1 : Form
{
private PortChecks MyPortCheck {get; set;}
public Form1()
{
InitializeComponent();
MyPortCheck = new PortChecks();
}
private void testCheck_Click(object sender, EventArgs e)
{
MyPortCheck .MyMethod();
}
...
}
Related
how do I access form1 string variable from a different class?
public partial class Form1: Form
{
public Form1()
{
InitializeComponent();
}
public string deva = "123";
//button
private void button8_Click(object sender, EventArgs e)
{
deva = "456";
}
private void button9_Click(object sender, EventArgs e)
{
Other ks = new Other();
ks.test_me();
}
}
public class Other: Form1
{
//trying to access Form1 variable.
public void test_me()
{
Form1 fm = new Form1();
MessageBox.Show(fm.deva);
//deva is 123 but not 456.
//I clicked on button and values changes it form1 however from here it assigns just default value
}
//
//Does creating a new form1 will reset its values?
//Somebody please help me. how to solve this issue.
}
public partial class Form1: Form {
public Form1()
{
InitializeComponent();
}
public string deva = "123";
//button
private void button8_Click(object sender, EventArgs e)
{
deva = "456";
}
private void button9_Click(object sender, EventArgs e)
{
Other ks = new Other(this);
ks.test_me();
}
}
no need to inherit from form1, please pass the object via constructor
public class Other {
Form1 obj = null;
public Other(Form1 object)
{
this obj = object;
}
public void test_me()
{
MessageBox.Show(obj.deva);
}
}
Make your variable deva Static. Access it with Class directly not object.
public static string deva = "123";
public void test_me()
{
//Form1 fm = new Form1();
MessageBox.Show(Form1.deva);
}
Answer on the title question.
Read Jon Skeet's comment for explanation of reason why your approach not workiing.
If you want have access to the variables of another instance, then you need in someway have reference to that instance
One way pass it in the constructor of Other
public class Other: Form1
{
private readonly Form1 _Form1;
public Other(Form1 form1)
{
_Form1 = form1;
}
public void test_me()
{
MessageBox.Show(_Form1.deva);
}
}
Then where you create new instance of Other pass instance of your Form1 ti the constructor of Other
public class Form1
{
private void button9_Click(object sender, EventArgs e)
{
Other ks = new Other(this);
ks.test_me();
}
}
default value is set a every new instance
if you want to keep last value you make a static property
public static string deva = "123";
How can I passing values from a Form to another one directly? A receiver Form will be showing itself on screen and listening passing values which will be sending from a main form.
I know a way to do that with delegate and event but mine is not my desired one.
I need that with opposite way. Below is what I can do those code lines. This able to do only Form2 passes value to Form1 (main form). I need this approach's opposite. So, Form1 will be sender Form2 will be receiver, and transmit in real-time while they are showing itself on the screen.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form2 f = new Form2();
f.IdentityUpdated += new Form2.IdentityUpdateHandler(Form2_ButtonClicked);
f.Show();
}
private void Form2_ButtonClicked(object sender, IdentityUpdateEventArgs e)
{
textBox1.Text = e.FirstName;
}
}
public partial class Form2 : Form
{
public delegate void IdentityUpdateHandler(object sender, IdentityUpdateEventArgs e);
public event IdentityUpdateHandler IdentityUpdated;
public Form2()
{
InitializeComponent();
}
private void Form2_Load(object sender, EventArgs e)
{
string sFirstName = txtFirstName.Text;
IdentityUpdateEventArgs args = new IdentityUpdateEventArgs(sFirstName);
IdentityUpdated(this, args);
}
}
public class IdentityUpdateEventArgs : System.EventArgs
{
private string mFirstName;
public IdentityUpdateEventArgs(string sFirstName)
{
this.mFirstName = sFirstName;
}
public string FirstName
{
get { return mFirstName; }
}
}
try this way
public partial class Form1 : Form
{
public delegate void IdentityUpdateHandler(object sender, EventArgs e);
public event IdentityUpdateHandler IdentityUpdated;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form2 form2 = new Form2();
form2.Show();
IdentityUpdated(this, new EventArgs());
}
}
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
Form1 form1 = (Form1)Application.OpenForms["Form1"];
form1.IdentityUpdated += Form1OnIdentityUpdated;
}
private void Form1OnIdentityUpdated(object sender, EventArgs eventArgs)
{
MessageBox.Show("received");
}
}
I want to Use an instance of a class made in Form 1 in Form 2 (i changed it to a list for simplicity of example code:
Not only that, I want Form 2 to be able to modify it (Clear it at some point).
The advice I got was this, although I was not told how due to "no spoonfeeding allowed"
namespace automationControls.FileTime
{
public class Form_Main : Form
{
public List<string> folderList; //<---- i want to access this.....
private void button_showForm2_Click(object sender, EventArgs e)
{
Form_Log ConfirmBoxForm = new Form_Log(this);
ConfirmBoxForm.Show();
}
}
//form_Main opens form_Log
namespace automationControls.FileTime
{
public partial class Form_Log : Form
{
public Form_Log(Form_Main _f1)
{
InitializeComponent();
}
private void Form1_FormClosing(Object sender, FormClosingEventArgs e)
{
How.Do.I.AccessForm_Main.folderList.Clear();//<---- ............. in this function
}
}
}
Answered:In the constructor of Form_Log, store the reference to _f1 somewhere you can access it from elsewhere in Form_Log
Why don't you use the constructor that you have already added your form?
private Form_Main _mainForm;
public Form_Log(Form_Main _f1)
{
InitializeComponent();
_mainForm = _f1;
}
private void Form1_FormClosing(Object sender, FormClosingEventArgs e)
{
var myList = _mainForm.folderList;
}
Try This,
public class Form_Main : Form
{
public List<string> folderList; //<---- i want to access this.....
private void button_showForm2_Click(object sender, EventArgs e)
{
Form_Log ConfirmBoxForm = new Form_Log(this);
ConfirmBoxForm.Show();
}
}
Form log :
public partial class Form_Log : Form
{
private Form_Main _mainForm;
public Form_Log(Form_Main _f1)
{
InitializeComponent();
_mainForm = _f1;
}
private void Form1_FormClosing(Object sender, FormClosingEventArgs e)
{
_mainForm.folderList.Clear();
}
}
I don't know how advanced is your project but in this situation i would use delegates. Here is how i would do it:
public delegate void ModifyCollectionHandler(string parameter);
public delegate void ClearCollectionHandler();
public partial class Form1 : Form
{
public List<string> folderList;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form2 form = new Form2()
form.ClearItem+=form_ClearItem;
form.AddItem+=form_AddItem;
form.DeleteItem+=form_DeleteItem;
}
void form_DeleteItem(string parameter)
{
if (folderList == null)
return;
folderList.Remove(parameter);
}
void form_AddItem(string parameter)
{
if (folderList == null)
folderList = new List<string>();
folderList.Add(parameter);
}
void form_ClearItem()
{
if (folderList != null)
folderList.Clear();
}
}
public partial class Form2 : Form
{
public event ModifyCollectionHandler AddItem;
public event ModifyCollectionHandler DeleteItem;
public event ClearCollectionHandler ClearItem;
public Form2()
{
InitializeComponent();
}
private void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
if (ClearItem != null)
ClearItem();
}
}
I hope I helped you :)
Best regards
in the Form1 put this :
public static List<string> folderList;
you can simply call it from any form ex:Form2 like this :
From1.folderList.Clear();
can sameone provide example code on how to call non-static method on form1 from form2.
form1
public Form1()
{
InitializeComponent();
}
public void prikazi()
{
MessageBox.Show("ok");
}
private void openf2_Click(object sender, EventArgs e)
{
Form2 frm = new Form2();
frm.Show();
}
form2
public Form2()
{
InitializeComponent();
}
private void callMethod_Click(object sender, EventArgs e)
{
// this don't work. If I change to public static void on form1 then it work's but I need non-static example
Form1.prikazi();
}
thanks
It doesn't matter if it's a form class, if you want to access a non-static method, there is no other alternative then to create an instance of the class.
But - It doesn't make sense.. so don't do it
Find other alternatives, like creating the method you need static in a common place, or consider adding this method (or a variation of it) to the form
form1
public Form1()
{
InitializeComponent();
}
public void prikazi()
{
MessageBox.Show("ok");
}
private void openf2_Click(object sender, EventArgs e)
{
Form2 frm = new Form2(this);
frm.Show();
}
form2
private Form1 parentForm;
public Form2(Form1 parentForm)
{
this.parentForm = parentForm;
InitializeComponent();
}
private void callMethod_Click(object sender, EventArgs e)
{
parentForm.prikazi();
}
But better learn to bundle reusable code in to a separate class, rather than passing around form instances.
You need to have an instance of the form to call the method.
There are a few ways that you can make this work
1) Pass an action through to the new form
public Form2()
{
InitializeComponent();
}
public Action yourAction {get; set;}
private void callMethod_Click(object sender, EventArgs e)
{
Action instance = yourAction;
if(instance != null)
instance();
}
then in Form 1 you can say
private void openf2_Click(object sender, EventArgs e)
{
Form2 frm = new Form2();
frm.yourAction = prikazi;
frm.Show();
}
2) You can pass an instance of Form1 into Form 2
So in Form 2 you have:
public Form1 ParentForm {get; set;}
private void callMethod_Click(object sender, EventArgs e)
{
if (ParentForm != null)
ParentForm.prikazi();
}
And Form1 you assign a value to the ParentForm variable
private void openf2_Click(object sender, EventArgs e)
{
Form2 frm = new Form2();
frm.ParentForm= this;
frm.Show();
}
public partial class Form1 : Form
{
internal static Form1 ViewForm1; // make other form run Public void
public form1()
{
InitializeComponent();
ViewForm1 = this; //Add this
}
public void DoSomething()
{
//Code...
}
}
......................
public partial class Form1 : Form
{
public form2()
{
InitializeComponent();
Form1.ViewForm1.ShowData(); // call public void from form1
}
I have two buttons in Form 1, one is "ShowForm2" button and one is "button1" button.
Button 1 is disable by default. And when I click "ShowForm2" button, Form 2 will show.
So, what I want is, when I click the "button2" in form 2, it will enable the "button1" in form 1.
So, I try to code like this in my form2 class:
public partial class Form2 : Form
{
bool enable_form1_button1;
public bool Enable_form1_button1
{
get { return this.enable_form1_button1; }
set { this.enable_form1_button1 = value; }
}
public Form2()
{
InitializeComponent();
}
private void button2_Click(object sender, EventArgs e)
{
enable_form1_button1 = true;
}
}
Then in my Form1 class, I am expecting to get the "enable_form1_button1 = true" to pass into form 1 and enable my form 1 button1. But how to do this?
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void btb_Showfrm2_Click(object sender, EventArgs e)
{
Form2 frm2 = new Form2();
frm2.Show();
button1.Enabled = frm2.Enable_form1_button1; // I put it here, and it just does not seems right
}
}
Well what you can do is, expose the button as a property and send a reference of your current form to the form that needs to take control:
Form1
public partial class Form1 : Form
{
public Button BtnShowForm2
{
get { return btnShowForm2; }
set { btnShowForm2 = value; }
}
private void btnShowForm2_Click(object sender, EventArgs e)
{
// pass the current form to form2
Form2 form = new Form2(this);
form.Show();
}
}
Then in Form2:
public partial class Form2 : Form
{
private readonly Form1 _form1;
public Form2(Form1 form1)
{
_form1 = form1;
InitializeComponent();
}
private void btnEnabler_Click(object sender, EventArgs e)
{
// access the exposed property here <-- in this case disable it
_form1.BtnShowForm2.Enabled = false;
}
}
I hope this is what you're looking for.
Form1.cs
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
button1.Enabled = false;
}
private void button2_Click(object sender, EventArgs e)
{
Form2 oFrm2 = new Form2();
oFrm2.evtFrm += new ShowFrm(oFrm2_evtFrm);
oFrm2.Show();
}
void oFrm2_evtFrm()
{
button1.Enabled = true;
}
}
Form2.cs
public delegate void ShowFrm();
public partial class Form2 : Form
{
public event ShowFrm evtFrm;
public Form2()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
if (evtFrm != null)
{
evtFrm();
}
}
}
you can send a refrence of your form1 to your form2 in the from2 constructor for example :
and then in button clicked event handler in form2 call a public method in form1 to enable the button :
this could be your form1 code :
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form2 frm = new Form2(this);
frm.Show();
}
public void enableButton()
{
button2.Enabled = true;
}
this could be your form2 code :
public partial class Form2 : Form
{
private Form1 frm;
public Form2(Form1 frm)
{
InitializeComponent();
this.frm = frm;
}
private void button1_Click(object sender, EventArgs e)
{
frm.enableButton();
}
If you'll only have one instance of Form1 you can also get away with having a static Button member in Program which references the button you want to enable from Form2.
Form1.cs:
using System;
using System.Windows.Forms;
namespace StackOverflow_2013_05_19_Form1_Form2_buttons
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
button2.Enabled = false;
Program.button = button2;
}
private void button1_Click(object sender, EventArgs e)
{ new Form2().Show(); }
private void button2_Click(object sender, EventArgs e) { }
}
}
Form2.cs:
using System;
using System.Windows.Forms;
namespace StackOverflow_2013_05_19_Form1_Form2_buttons
{
public partial class Form2 : Form
{
public Form2()
{ InitializeComponent(); }
private void button1_Click(object sender, EventArgs e)
{ Program.button.Enabled = true; }
}
}
Program.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
namespace StackOverflow_2013_05_19_Form1_Form2_buttons
{
static class Program
{
public static Button button;
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
I would recommend you to use event/delegates to perform this task. This is the standard way of doing so.
Again passing reference in constructor or making static func/var/properties are just workaround and Called as bad programming.