I have a C# Winforms Application and I'm using the main form to control the other this way:
public Rel_Entitys RelForm1;
public Struct_Inc StructForm1;
public DataLoad DataLoadForm1;
public Asset_Inc AssetForm1;
public Estimates_Inc EstimatesForm1;
public Options OptionsForm1;
private void Form1_Load(object sender, EventArgs e)
{
RelForm1 = new Rel_Entitys();
StructForm1 = new Struct_Inc();
DataLoadForm1 = new DataLoad();
AssetForm1 = new Asset_Inc();
OptionsForm1 = new Options();
EstimatesForm1 = new Estimates_Inc();
}
And then I access them this way:
private void barButtonItem6_ItemClick(
object sender, DevExpress.XtraBars.ItemClickEventArgs e)
{
StructForm1.Show();
this.Hide();
}
Is working fine for me to load data from database to this forms but when I try to get any value from any field they are null/empty. I already tried to use this.StructForm1.txt1.Text but nothing returns. What am I doing wrong? I use this form declaration to become more easy handle the form and call your methods but I not sure that is the right way to do it.
[Update]
I'm starting to think that is something related to my methods. If a set a value for the field on form_load and then get it from the method
public void SaveEstimate() {...}
It is empty again. Any ideas?
Looks like you are creating multiple instances of forms. Just a quick check. Make the fields static and then see if these are still Null(empty).
public static Rel_Entitys RelForm1;
public static Struct_Inc StructForm1;
public static DataLoad DataLoadForm1;
public static Asset_Inc AssetForm1;
public static Estimates_Inc EstimatesForm1;
public static Options OptionsForm1;
Make sure that the textbox you call txt1 is Public.
Select your textbox, go to the properties window, find Modifiers and set it to Public.
Related
I know this might look silly but I got a strange problem in my winforms. I have a windows application in which after a particular set of operations are completed I want to populate a Checked ComboBox. I am doing this using two classes. I want to copy a array from helper class to the form class. Array gets copied when AddArrayItems method is called. But when I see the ComboBox in the form, its null. After debugging with watch variables I got to know that the problem is after copying the array to Form1 array, as soon the control goes back to the caller, the array items are deleted. I tried to replicate my stuff, not exactly but still similar to what I am doing.
My code looks like this:
using System;
using System.Windows.Forms;
namespace DemoApp
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
string[] cboxAr;
public void AddCmboBoxItems(string[] cbArry)
{
cboxAr = new string[cbArry.Length];
Array.Copy(cbArry, 0, cboxAr, 0, cbArry.Length);
//cbArry.CopyTo(cboxAr, 0);
//foreach (string s in cboxAr)
//comboBox1.Items.Add(s);
comboBox1.Show();
}
private void button1_Click(object sender, EventArgs e)
{
HelperClass.DoSomething();
}
}
public class HelperClass
{
public HelperClass()
{
}
public void HelperMethod()
{
SomeMethod();
}
private void SomeMethod()
{
string[] partnrName = new string[5] { "str1", "str2", "str3", "str4", "str5"};
Form1 f = new Form1();
f.AddCmboBoxItems(partnrName);
}
public static void DoSomething()
{
new HelperClass().HelperMethod();
}
}
}
I don't understand what exactly the problem is here. Can anyone please push me in the right direction. Thanks in advance.
You're never showing the form after modifying its controls:
Form1 f = new Form1();
f.AddCmboBoxItems(partnrName);
But you're calling this from within an existing form:
private void button1_Click(object sender, EventArgs e)
{
HelperClass.DoSomething();
}
Presumably you want to modify the controls on that form? Then you'll need a reference to that form. Pass one to the method:
private void button1_Click(object sender, EventArgs e)
{
HelperClass.DoSomething(this);
}
And accept it in the method definition:
public static void DoSomething(Form1 form)
{
new HelperClass().HelperMethod(form);
}
And so until the point where you need to use it. (Side note: You have a lot of weird indirection happening here with a seemingly random mix of static and instance methods and classes. You can simplify a lot, which will make this involve fewer code changes.)
Ultimately, SomeMethod needs the instance of the form to modify:
private void SomeMethod(Form1 form)
{
string[] partnrName = new string[5] { "str1", "str2", "str3", "str4", "str5"};
form.AddCmboBoxItems(partnrName);
}
To illustrate the overall point, consider an analogy...
A car rolls off of an assembly line. You open the trunk and put a suitcase inside. Moments later another car rolls off of the same assembly line. It is identical to the first car in every way. When you open the trunk of the second car, do you expect to find your suitcase inside it?
A Form is an object like any other. Changes made to one instance of an object are not reflected in other instances of the same object. Each instance maintains its own state. In order to modify a particular instance, you need a reference to that instance.
I'm currently developing a Windows Form Application that uses two forms. I have no problems linking between the two forms. My issue is accessing a variable in Form2 that was created in Form1. How do you make a variable accessible to multiple forms in the same project?. I honestly tried to look for an answer, but could not find anything. Any help would be appreciated.
Here is the code for Form1:
namespace HourlyAlarm1
{
public partial class AlarmToneSetter : Form
{
public bool halfHourSelected;
public AlarmToneSetter()
{
InitializeComponent();
}
private void okButton_Click(object sender, EventArgs e)
{
if(halfHourRadio.Checked)
{
halfHourSelected = true;
}
else
{
halfHourSelected = false;
}
Form1 f1 = new Form1();
f1.ShowDialog();
}
public bool getHalfHourSelect()
{
return halfHourSelected;
}
}
}
Here is the code for Form2:
namespace HourlyAlarm1
{
public partial class Form1 : Form
{
int min;
System.Media.SoundPlayer sp;
public Form1()
{
InitializeComponent();
}
private void playSound()
{
sp = new System.Media.SoundPlayer(HourlyAlarm1.Properties.Resources.chipfork);
sp.Load();
sp.Play();
}
private void timer1_Tick(object sender, EventArgs e)
{
TimeLabel.Text = DateTime.Now.ToLongTimeString();
min = DateTime.Now.Minute;
if(HourlyAlarm1.AlarmToneSetter.g)
if(min == 0)
{
playSound();
}
}
}
}
If you want a variable which is accessible to any form within the project, mark it as static. That way you don't need a specific instance of the class that it's in to be able to access it.
You can use the forms Tag property if you want to pass just one variable.
Form1 f1 = new Form1();
f1.Tag="some value";
f1.ShowDialog();
and then in form 2 access it via it's own Tag property. Since it is stored as an object you will have to convert it to whatever datatype your application requires.
Example for getting the value in the new form:
string value = this.Tag.ToString();
As the question currently stands, it looks like you're trying to edit the halfHourSelected field in your AlarmToneSetter class from the Form1 class. To do that, there are several options:
Since this field is already public you can simply edit it like this (form Form1):
HourlyAlarm1.AlarmToneSetter.halfHourSelected = true;
or, if you plan on using it several times, add
using HourlyAlarm1;
/**
* declare the namespace, the class, etc.
*/
AlarmToneSetter.halfHourSelected = true
(Edit: As mentioned by Jason, this can be rewritten to be a property and comply with the style guide) However, since you already wrote a Java-style getter for this field, you should rewrite it in C# style; changing the declaration to
public bool HalfHourSelected{get;set;};
which will add the getter and setter for the property automatically.
Now, if you want to make this field persistent (that is, the configuration value should be saved across multiple executions of the program) then you should consider adding it to the settings of your project, and reference it like this
HourlyAlarm1.Properties.Settings.Default.halfHourSelected = true;
HourlyAlarm1.Properties.Settings.Default.Save();
or, as always, if you're gonna access them several times,
using HourlyAlarm1.Properties;
/**
* declare the namespace, the class, etc.
*/
Settings.Default.halfHourSelected = true;
Settings.Default.Save();
Yes, this is my first time answering a question in SO. If you have any recommendations, let me know in the comments! I'll appreciate the feedback.
Pass them as parameter of constructor. This way is used to set once time at creating an instance of class
public Form1(int i, string s, object o){}
Create public get/set. This way is used to set multiple times, but their value will be different among instances of class.
public int Price { get; set;}
Form1 frm1 = new Form1();
frm1.Price = 123;
Create public static field. This way is used to set multiple times, and it is same among instance of class.
public static int Price = 0;
Form1.Price = 123;
First of all public fields are discouraged in .NET: you should use properties.
Your problem is that bool is a value type and you can't "bind" it between forms, you need a reference type.
public class ReferenceBoolean
{
public bool Value{get;set;}
}
public class Form1
{
protected ReferenceBoolean HalfHourSelectedReference{get;set;}
public bool HalfHourSelected
{
get{return this.HalfHourSelectedReference.Value;}
set{this.HalfHourSelectedReference.Value = value;}
}
public Form1()
{
this.HalfHourSelectedReference = new ReferenceBoolean();
}
}
public class Form2
{
protected ReferenceBoolean HalfHourSelectedReference{get;set;}
public bool HalfHourSelected
{
get{return this.HalfHourSelectedReference.Value;}
set{this.HalfHourSelectedReference.Value = value;}
}
public Form2(ReferenceBoolean halfHourSelected)
{
this.HalfHourSelectedReference = value;
}
}
Now this might look all fine and dandy but there is one thing I did not do, because I'm not sure if you need it, if you update this value and have it bound to the UI in your form the update will not be reflected in the form. To do that you must implement something like the IPropertyNotificationChange pattern, which works much better in WPF.
I am brand new to C# (I apologise if my question is noobish - I'm teaching myself, so it's a bumpy process). I am trying to develop a winform and since some of the methods are pretty long, I am trying to keep it in a couple classes. This is what I'm kind of hoping to achieve:
public partial class formMainForm : Form
{
public formMainForm()
{
InitializeComponent();
}
private void UpDown1_ValueChanged(object sender, EventArgs e)
{
longCalculations.LongMethod1();
}
}
public class longCalculations
{
private void LongMethod1()
{
// Arbitrarily long code goes here
}
}
I'm doing this in an attempt to keep the formMainForm class tidy and be able to split any calculations into manageable chunks. However, I'm encountering problems with using form controls (e.g. check boxes, numeric up-down controls, etc.) in my non-form classes.
If I leave them as is (e.g. CheckBox1) I get a the name does not exist in the current context error. I searched around and I found that it's because that box is defined in a different class. However, if I change it to formMainForm.CheckBox1, the error is now an object reference is required for the non-static field, method or property. Again, I looked around and it appears that that is due to the form initialization method not being static.
If I change public formMainForm() to static formMainForm(), the error now moves to InitializeComponent(); and I do not know where to go from here. I also tried making an instantiation of the formMainForm() method, but that didn't do anything (the code I attempted to use is below. I found it somewhere on this site as an answer to a similar problem).
private void formLoader(object sender, EventArgs e)
{
shadowrunMainForm runForm = new shadowrunMainForm();
runForm.Show();
}
How can I use the formcontrol names in other classes?
P.S. It is my first post here - I am super sorry if I have missed this question already being asked somewhere. I did search, but I didn't find what I was looking for.
EDIT
It seems I hadn't made myself clear - this was just an example of code and my problem is with the second class, not the first one. I have now simplified the code to:
public partial class formMainForm : Form
{
public formMainForm()
{
InitializeComponent();
}
}
public class longCalculations
{
private void LongMethod1()
{
List<CheckBox> listOfBoxes = new List<CheckBox>();
listOfBoxes.Add(CheckBox1);
// The code displays an "object reference is required for the non-static field, method or property" error at this stage. Changing the "CheckBox1" to formMainForm.CheckBox1 doesn't help
// Arbitrarily long code goes here
}
}
LongMethod1 works perfectly fine when placed in the formMainForm partial class. Moving it to the other form makes it unable to take data from those checkboxes.
I believe this line longCalculations.LongMethod1(); is throwing error cause you are trying to access a instance method as if it's a static method and as well it's defined as private method which won't be accessible outside the class. You need to create an instance of longCalculations class before accessing any of it's member or method(s) and mark the method public like
private void UpDown1_ValueChanged(object sender, EventArgs e)
{
longCalculations ln = new longCalculations();
ln.LongMethod1();
}
public class longCalculations
{
public void LongMethod1()
{
// Arbitrarily long code goes here
}
}
(OR) If you really want it to be a static method then define accordingly with static modifier like
public class longCalculations
{
public static void LongMethod1()
{
// Arbitrarily long code goes here
}
}
Now you can call it like the way you are trying
public static class longCalculations
{
public static void LongMethod1()
{
// Arbitrarily long code goes here
}
}
If you're going to make a call longCalculations.LongMethod1();, then you need to make your class static as such.
Or you leave it as not static method by calling
longCalculations lc = new longCalculations()
lc.LongMethod1();
As for accessing controls in separate classes, you can pass in the form and make the controls public which can be dangerous.
So on your Form.designer.cs, change any control you may have to public modifier. Then you would make a call like this...
private void UpDown1_ValueChanged(object sender, EventArgs e)
{
longCalculations.LongMethod1(this);
}
public void LongMethod1(Form1 form)
{
// Arbitrarily long code goes here
form.label1.Text = someString;
//more settings and whatnot
}
Or do something like this:
public class longCalculations
{
public string LongMethod1()
{
// Arbitrarily long code goes here
return myString;
}
}
longCalculations lc = new longCalculations()
string result = lc.LongMethod1();
this.label1.Text = result;
Ideally, your longCalculations class would not attempt to modify the form directly. Instead it would return an object that the form could use to update its controls.
If you need to access the form directly from the longCalculations class, first change the method to accept an instance of your form
public void LongMethod1(formMainForm myForm)
Then you can pass the form itself as a parameter
var calc = new longCalculations();
calc.LongMethod1(this);
In your other class, you need to have an instance of your formMainForm class:
var myForm = new formMainForm();
Then you can access its members like this:
myForm.CheckBox1.Checked = true;
I'm trying to create a hashtable of filesystem watchers. This is to keep a running record of active filesystemwatchers with the directories they are watching as keys. Then via a form the user can add and delete folders to watch, which are visible in a listview or something.
My main problem is how to "keep" the hash table between methods and classes. I'm a bit of a novice to C# and it doesn't seem to work the way I'm used to in VB.NET.
So I have (stripped down to simplify):
public partial class MainForm : Form
{
public static Hashtable globalHashTable;
public MainForm()
{
InitializeComponent();
}
public void Button1Click(object sender, EventArgs e)
{
FileSystemWatcher watcher1 = new FileSystemWatcher(#"C:\");
globalHashTable.Add(#"C:\",watcher1);
}
}
}
So that a filesystemwatcher is added to the hashtable. However since the globalhashtable is static (?) this won't work. Making it non static means I have to create an instance of it when the buttton is pressed, so I have a new one each time as it's not "kept". My problem is how to keep a table in memory between methods and classes.
I'm fairly sure I've majorly misunderstood something as I'm new to all of this. Also I doubt this is even a half decent way to do this, if anyone has a better way, then please go ahead!
Thanks,
Matt
Expanding on #Ron Beyer's suggestion you can do something like this:
private Dictionary<string, FileSystemWatcher> _fileSystemWatcherMap;
public MainForm()
{
InitializeComponent();
_fileSystemWatcherMap = new Dictionary<string, FileSystemWatcher>();
}
public void Button1Click(object sender, EventArgs e)
{
string pathToWatch = #"C:\"; // Must be a different path each time otherwise will throw
var watcher = new FileSystemWatcher(pathToWatch);
_fileSystemWatcherMap.Add(pathToWatch, watcher);
}
This way all methods in the MainForm can access the file watchers.
If you need to share this among forms that are created from MainForm you can simply pass this data before showing the dialog.
If the other form is created in a different way the you can create a static class like this:
public static class FileWatcherMap
{
private static Dictionary<string, FileSystemWatcher> _fileSystemWatcherMap = new Dictionary<string,FileSystemWatcher>();
public static void AddWatcher(string path, FileSystemWatcher fsw)
{
_fileSystemWatcherMap.Add(path, fsw);
}
public static void RemoveWatcher(string path)
{
_fileSystemWatcherMap.Remove(path);
}
}
then in the click handler you add the watcher to this list:
public void Button1Click(object sender, EventArgs e)
{
string pathToWatch = #"C:\"; // Must be a different path each time otherwise will throw
var watcher = new FileSystemWatcher(pathToWatch);
FileWatcherMap.AddWatcher(pathToWatch, watcher);
}
Now FileWatcherMap class would be accessible from any other form
Now before anyone goes and marks this question as a duplicate, I'd like to say that my problem differs from the other ones. I'm trying to open an existing Form from another, but I'm having problems in the sense that I've set some Forms to 'host' others (To transfer variables between them). Here's what I mean:
public partial class Schedule_Tasks : Form
{
readonly Schedules schedules;
public Schedule_Tasks(Schedules host)
{
this.schedules = host;
InitializeComponent();
}
So in this snippet of code, I'm trying to get the value of some variables from the Schedules form, into the Schedule_Tasks Form. So I've used the 'host' system. SO far this method works fine, but my problem occurs when I try to open a specific Form, from another that isn't 'hosting'. For example using:
new Schedules().Show();
So obviously when I'm declaring this, I'd put something like 'this' in the brackets after Schedules, but that doesn't work if the Form is being called outside of the 'host' Form. I'd just like to now is there something I'm missing or can change? Please let me know if any part isn't clear, it's a little difficult to explain. Any help is appreciated, Cheers.
EDIT
Here's the code that I'm working with now:
public partial class Schedual_Tasks : Form
{
readonly Scheduals scheduals;
public string selectedDevice;
public string getPath;
public string totalPath;
public Schedual_Tasks(Scheduals host)
{
this.scheduals = host;
InitializeComponent();
selectedDevice = scheduals.itemSelected;
}
private void Schedual_Tasks_Load(object sender, EventArgs e)
{
}
private void changeDirectory_Click(object sender, EventArgs e)
{
new Folder_Browser(this).Show(); //Error Occurs here
}
}
And here is the constructor for Folder_Browser, which is the Form I'm trying to call:
readonly Back_up_Options backOptions;
public string deviceSel;
public Folder_Browser(Back_up_Options host)
{
InitializeComponent();
this.backOptions = host;
deviceSel = backOptions.deviceSel;
}
Your (Folder_Browser) Form's constructor is declared as
public Folder_Browser(Back_up_Options host)
That means you cannot pass a Schedual_Tasks instance as the host parameter because there is no way to convert from a Schedual_Tasks object into a Back_up_Options object. The compiler detects this and creates an error message.
If you cannot pass the host parameter, you can pass null instead:
new Folder_Browser(null).Show();
But then you need to make sure that you check the backOptions member for null reference each time you use it. For example:
if(backOptions != null)
{
deviceSel = backOptions.deviceSel;
}
else
{
deviceSel = null;
}
That in turn means that you will need to check deviceSel for null each time you use it and so on.
And of course, using your Form without a "host" needs to be possible at all. If you have code that requires a "host", it will fail.