Newbie here. I'm running Visual Studio C# Express 2008. I have two Windows Forms, each with a TextBox. The textboxes update within the same class but not as the result of a invoked method from outside the class. I need to be able to update tbRooms.Text when the UpdateListOfRooms() method is invoked. I've outlined the problem in pseudo-code below. I appreciate your help!
fLocations.cs
fLocations_Load()
{
this.tbLocations.Text = Properties.Settings.Default.LocationID + " locationsLoad"; --updates
}
dgvLocations_SelectionChanged()
{
var rooms = new fRooms();
rooms.tbRooms.Text = Properties.Settings.Default.LocationID + " locationssSelectionChanged"; --updates
rooms.UpdateListOfRooms();
}
fRooms.cs
fRooms_Load()
{
this.tbRooms.Text = Properties.Settings.Default.LocationID + " roomsLoad"; --updates
}
UpdateListOfRooms()
{
this.tbRooms.Text = Properties.Settings.Default.LocationID + " roomsUpdateListOfRooms"; --does NOT update; still says "roomsLoad"
}
Updated 8/20/14:
I've been a busy bee :) I read all the parts of the tutorial by #jmcilhinney and decided to approach this by including references to the two forms, Locations and Rooms, in the MainMenu class that launches them:
(MainMenu.cs) Instances of Locations and Rooms are created. In the constructor, 'rooms' is passed to the 'locations' instance and both forms are shown.
(Locations.cs) Another Rooms instance is created at class scope so it can be seen by all methods of the class. In the constructor, this instance is set to the one being passed by MainMenu which means that this class is working with the same instance created in MainMenu. When the user changes the selection on dgvLocations, the 'dgvLocations_SelectionChanged' event is fired which invokes the Rooms.UpdateRooms method.
(Rooms.cs) The 'UpdateRooms' method displays a new set of rooms based on the passed value of 'locationID'.
This link was helpful. Visual C# - Access instance of object created in one class in another.
public partial class MainMenu : Form
{
Locations locations;
Rooms rooms;
public MainMenu()
{
rooms = new Rooms();
locations = new Locations(rooms);
locations.Show();
rooms.Show();
InitializeComponent();
}
}
public partial class Locations : Form
{
Rooms rooms;
public Locations(Rooms r)
{
rooms = r;
InitializeComponent();
}
private void Locations_Load(object sender, EventArgs e)
{
// Populate this.dgvLocations using SQL query.
}
private void dgvLocations_SelectionChanged(object sender, EventArgs e)
{
// Update the rooms instance with current locationID.
rooms.UpdateRooms(dgvLocations.CurrentCell.Value.ToString());
}
}
public partial class Rooms : Form
{
public Rooms()
{
InitializeComponent();
}
private void Rooms_Load(object sender, EventArgs e)
{
// Populate this.dgvRooms using SQL query.
}
public void UpdateRooms(string locationID)
{
// Update dgvRooms based on user changing the locationID in dgvLocations
}
}
In the first code snippet, you create a new fRooms object but you never call its Show or ShowDialog method, which means that you never display it to the user. That means that any changes you make to that form will not be seen. Presumably the user can see an fRooms object though, but you are not making any changes to that one.
Consider this. Let's say that I give you a note pad and you open it and look at the first page. Let's say that I now buy a new note pad and write on the first page of it. Would you expect to see the words I wrote magically appear on the page in front of you? Of course not. We both are holding a note pad but they are two different note pads. You're looking at one and I'm writing on the other, so you won;t see what I write.
The same goes for your forms. They are both fRooms objects but they are two different fRooms objects. Changes you make to one will not affect the other. If you want the user to see the changes you make then you must make those changes to the fRooms object that the user is looking at.
Related
First off, I'm a beginner in object oriented programming in which I'm currently finishing my final c# project.
BRIEF rundown, I have made a library class(dll) which I made it for a console application. This was my first project and then for this project I have to reuse the dll for a WPF application. I adapted my code for WPF.
I have a MainWindows for login, windows1 where the main program is working and calling the dll( collection base classes, specific name such has artist, curator and art).
My issue is that I have to use windows2 (study purpose) to sell an art. I call the dll class method which accepts 2 parameters such as (string IDArt, double SellPrice).
The mistake I did was to recreate a new instance of gallery in windows2.
I understand that I have to somehow send my(this) instance to windows2 and then retrieve the change to windows1.
I'm wondering how should I approach this issue. Please be advised that I understand c# from what I learned but i'm so far from truly knowing it and mastering it. Thanks in advance!
Since C# is object-oriented, the right way to do this thing would be to create an instance of your Collection class in a lower abstract layer than a window itself (since you plan to reuse the same collection in more than one window) - for example, statically in the global App context - and then use data binding to synchronize the collection between your windows. (For this to work as expected, in real time, your Collection class needs also to implement IObservable and INotifyPropertyChanged to inform the window's context that it needs to be refreshed with new elements.)
There are so many ways to do this, I tell you some of them..
If you want to access MainWindow fields or properties from elsewhere, you can do it like this:
In Window2:
//Calling MainWindow from Window2
var form = App.Current.MainWindow as ManinWindow;
form.textBox1.Text = "My Art";
MessageBox.Show(form.textBox1.Text);
or you can pass arguments from you Window1 to Window2 like this:
//Window 1
private void btnShowWindow2_Click(object sender, RoutedEventArgs e)
{
var form = new Window2("My Art", 100);
form.Show();
}
//Window 2 Constructor
public Window2(string ArtName, int Price)
{
MessageBox.Show("ArtName: " + ArtName + "\nPrice: " Price.ToString() + " dollars");
}
or
//Window1
private void btnShowWindow2_Click(object sender, RoutedEventArgs e)
{
var form = new Window2()
{
Price = 200,
ArtName = "My Art"
};
form.Show();
}
//Window2
public string ArtName {get; set;}
public int Price {get; set;}
private void Window2_Loaded(object sender, RoutedEventArgs e)
{
MessageBox.Show("ArtName: " + ArtName + "\nPrice: " Price.ToString() + " dollars");
}
probably the easiest way to do this would be to use the application's settings, also one of my favorite ways, go to "Project\WpfApp1 Properties" and go to "Settings" tab, there you can create your settings, create 1 setting name it "IDArt" and set it to a string type and another setting name it "SellPrice" and set it to double type.
now to access these settings all youhave to do is use this code:
WpfApp1.Properties.Settings.Default.IdArt;,
WpfApp1.Properties.Settings.Default.SellPrice;
I'm trying to pass a variable from one form to another form textbox. The 'variable' is a result of a calculation based on the user inputs.
Below is the code for the parent form(RuleInsertForm) where I'm calling the subform(Helpformula) to get the user inputs.
public partial class RuleInsertForm : Form
{
public string helpformulainputs;
}
private void RuleInsertForm_Load(object sender,EventArgs e)
{
if (helpformulainputs=="")
{
textBox_Inputs.Text = "";
}
else
{
textBox_Inputs.Text = helpformulainputs;
}
}
Below is the code for the subform(Helpformula) where i'm passing the result variable(formulainputs) to the parent form(RuleInsertForm).
public partial class HelpFormula : Form
{
public string formulainputs = string.Empty;
private void button_generateformula_Click(objectsender, EventArgs e)
{
using (RuleInsertForm insertform = new RuleInsertForm())
{
insertform.helpformulainputs = formulainputs;
this.Close();
insertform.Show();
}
}
}
Problem:
The values are getting passed to the text box but in the UI its not getting dispalyed.
so far I tried to push data back to parent form and then tried to display the data in the textbox where I failed.(I dont know where it went wrong suggest me if I can resolve the below one)
Now I need an alternative method to this for eg: instead of pushing the data back to parent form i need to make the variable available for all the forms trying to use the subform(formulainputs)
How can I acheive this process ? any suggestions are much appreciated.
The problem seems to be that insertForm.Show() does not block the execution of your button handler. Show opens the insertform as non-modal.
So after insertform is opened, the execution is continued in button_generateformula_Click and when you exit the using block, the insertform is disposed and therefore closed.
To solve this you may call insertForm.ShowDialog() instead.
For different ways of communicating between Forms look here or simply type communicate between forms into the SO search box.
I have the following snippet of code that allows me to pull the properties from an object in my list and assign them to variables in other forms. However, I need to be able to pull the data from my variables in the other form and use those to set the properties of the given object.
My class Account is used to populate my list accounts. On my next form AccountMenu I have a class Variables1 that contains accessible variables that are used throughout the rest of my forms to keep track of the checking balance and saving balance. When logging off from the AccountMenu, I want to be able to pass the values from Variables1 to the account that was initially used.
I know how to pass variables from one form to another, but I'm not really sure how to update the form automatically, without a button, on the original form. Thus, the solution that I see is that I have a button on my AccountMenu form that "logs" the user out, via this.close(); Additionally, I guessed that under that button, I need to have some code that assigns the variables as properties to the object. I'm just not sure how I can access the set properties of the object, since it is dynamically called with the code below.
Can someone help me figure out what I need to do? Below is some of the relevant code so that you can see how I have things set up. I am just not sure how to access "matches" from the other form in order to update that specific object properties. Thank you, anyone, who can help!
//variable that will be used to check textbox1.Text
string stringToCheck;
//array of class Account
List<Account> accounts = new List<Account>();
public MainMenu()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
//set value to user's input
stringToCheck = textBox1.Text;
//set a var that only returns a value if the .Name already exists
var matches = accounts.FirstOrDefault(p => p.Name == stringToCheck);
//check through each element of the array
if (matches == null)
{
accounts.Add(new Account(stringToCheck));
textBox1.Text = "";
label3.Visible = true;
}
else if (matches != null)
{
//set variables in another form. not sure if these are working
Variables1.selectedAccount = matches.Name;
//is this calling the CheckBalance of the instance?
Variables1.selectedCheckBalance = matches.CheckBalance;
//same thing?
Variables1.selectedSaveBalance = matches.SaveBalance;
//switch to form
AccountMenu acctMenu = new AccountMenu();
this.Hide();
acctMenu.Show();
}
}
As per my understanding I think what you required is kind of trigger on your parent form that needs to be called from your child application.
If that is what you required than you can go with defining an event on your AccountMenu form. and register this event from your Accounts form.
Than simply raise this event from your AccountMenu subform.
Deletegates and Events are really works like magic :)
Let me show you some code how to do this.
Code required in AccountMenu window:
public delegate void PassDataToAccounts(string result);
public event PassDataToAccounts OnPassDataToAccount;
protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
{
if (OnPassDataToAccount != null)
OnPassDataToAccount("result");
base.OnClosing(e);
}
Code required in Accounts window button1_Click event where the AccountMenu will open:
//set variables in another form. not sure if these are working
Variables1.selectedAccount = matches.Name;
//is this calling the CheckBalance of the instance?
Variables1.selectedCheckBalance = matches.CheckBalance;
//same thing?
Variables1.selectedSaveBalance = matches.SaveBalance;
//switch to form
AccountMenu acctMenu = new AccountMenu();
acctMenu..OnPassDataToAccount += childwindow_OnPassDataToAccount;
this.Hide();
acctMenu.Show();
}
void childwindow_OnPassDataToAccount(string result)
{
if (result == "result")
{
// Processing required on your parent window can be caried out here
//Variables1 can be processed directly here.
}
}
Ok so I'm attempting to create a simple game. In a nutshell it's a resource management game where the player will attempt to manage a thieves guild. In regards to running missions I've created a Thief class, a new instance of which is created when a new thief is recruited. I have coded within the thief class the ability to gain experience and level up.
Here's my specific problem:
I want the player to be able to select which thief/thieves to send on a mission. I have thought about it and figured that opening a new form and populating it with checkboxes is the easiest way to allow this. These checkboxes will be related to a List<thief> of thieves, the player then checks the thieves s/he wants to send and these are then stored in another List<thief> and passed on to the run mission function.
I've built a separate project with the intention of testing and playing around with this before putting it into the main program. The test project consists of two forms: The first (frmMain) with a textbox to hold the selected options and a button to open the second form (frmSelect). Currently I can open and populate the second form (frmSelect) but when I try to add the checked options to the textbox I simply...well can't.
So far I have tried directly accessing the textbox by typing frmMain.txtOptionsDisplay in the cs file of frmSelect but it causes the following error:
An object reference is required for the non-static field, method or
property
I tried to create a new form in frmSelect and make it equal to the active instance of frmMain with: Form frmTemp = frmMain.ActiveForm; and then alter the textbox using frmTemp as a go-between but that produced the error:
'System.Windows.Forms.Form' does not contain a definition for
'txtOptionsDisplay'.
Having searched both google and stackoverflow forums I've encountered answers that I either have never heard of (Threading) or answers that I kind've recognise but can't interpret the code pasted to make it relevant to my problem (delegates).
Any advice or pointers would be fantastic.
EDIT:
frmMain code:
public frmMain()
{
InitializeComponent();
selections.Add("Option 1");
selections.Add("Option 2");
}
private void btnClick_Click(object sender, EventArgs e)
{
frmSelectOptions.Show();
int length = selections.Count();
for (int i = 0; i < length; i++)
{
CheckBox box = new CheckBox();
box.Text = selections[i];
box.AutoSize = true;
box.Location = new Point(50, 50*(i+1));
frmSelectOptions.grpControls.Controls.Add(box);
}
}
public void updateText(string option)
{
txtOptionsDisplay.Text += option;
}
}
frmSelect code:
public List<CheckBox> selectedOptions = new List<CheckBox>();
Form frmTemp = frmMain.ActiveForm;
public frmSelect()
{
InitializeComponent();
}
private void btnSelect_Click(object sender, EventArgs e)
{
foreach (CheckBox box in grpControls.Controls)
{
if (box.Checked == true)
selectedOptions.Add(box);
}
this.Hide();
}
}
I hope this formats correctly... I'm kinda new and don't know how to indent. Oh look there's a preview...
Does this help?
Your problem is that controls defined within a form by default receive the private access identifier. Hence you could just add a property along the lines of
public ControlType ProxyProperty {
get {
return txtOptionsDisplay;
}
}
Besides from that you should think about wether what you're trying is actually a good solution. Manipulating forms from one to another will become a huge clusterfuck in terms of maintenance later on.
I'd suggest using the Singleton pattern for your frmMain. This will help safeguard you from accidentally launching another instance of frmMain and at the same time, will give you access to frmMain's objects. From there, you can either write accessors to Get your txtOptionsDisplay or you can make it public. Below is an example:
public class frmMain
{
private static frmMain Instance = null;
private static object LockObj = new object();
public static frmMain GetMain()
{
// Thread-safe singleton
lock(LockObj)
{
if(Instance == null)
Instance = new frmMain();
return Instance;
}
}
public string GetOptionsDisplayText()
{
return txtOptionsDisplay.Text;
}
}
public class frmSelect
{
private void frmSelect_Load(object sender, EventArgs e)
{
// Set whatever text you want to frmMain's txtOptionsDisplay text
txtDisplay.Text = frmMain.GetMain().GetOptionsDisplayText();
}
}
If you do go this route, don't forget to update Program.cs to use frmMain's singleton.
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
// Application.Run(new frmMain()); - Old method
Application.Run(frmMain.GetMain());
}
I've been trying to reset my current form to it's original state by closing it, and opening a new one. I want the form objects to be reset,the variables to be re-declared, the class objects to be cleared etc I've got everything working but the class being cleared, no matter what I do it won't create a new one with blank data.
Here is my code:
if (btnRandom.Text == "Reset")
{
SetupScreen form = new SetupScreen();
form.Show();
this.Dispose();
//Create new class for form / or launch load events as normal
form.Mybattleship = new battleship()
form.SetupScreen_Load(this, null);
}
I've tried many methods over the internet and none have worked.. even the overly complicated ones..
Oh I forgot to mention I need the new form to act as if it's just been loaded as normal, so the load events etc trigger
You would be better off making a method that you can call that will set default values for items that you can use when opening form and resetting...
public SetupScreen()
{
InitializeComponent();
SetDefaultValues();
}
private void SetDefaultValues()
{
//start values..
}
public void ResetBtn_Click(object sender, EventArgs e)
{
SetDefaultValues();
}