how to pass class to another form? - forms

Question

im trying to passing a class which preserves the values in it across all forms. but i have no idea how to do it.
my default class:
namespace bankaccount
{
class Account
{
private string _name, _accountNo, _accountType;
private double _balance = 0;
public string Name
{
get{ return _name;}
set{ _name = value;}
}
public string AccountNo
{
get { return _accountNo; }
set { _accountNo = value; }
}
public string AccountType
{
get { return _accountType; }
set { _accountType = value; }
}
public double Balance
{
get { return _balance; }
set { _balance = value; }
}
public Account()
{
}
public Account(string name, string accountNo, string accountType, double balance)
{
_name = name;
_accountNo = accountNo;
_accountType = accountType;
_balance = balance;
}
public double withdraw(double withdraw)
{
return _balance = _balance - withdraw;
}
public double deposit(double deposit)
{
return _balance = _balance + deposit;
}
}
}
main menu form:
public partial class frmMainMenu : Form
{
public frmMainMenu()
{
InitializeComponent();
}
public void btnNewAccount_Click(object sender, EventArgs e)
{
this.Hide();
frmNewAccount NewAccount = new frmNewAccount();
NewAccount.Show();
}
public void btnDeposit_Click(object sender, EventArgs e)
{
this.Hide();
frmDeposit Deposit = new frmDeposit();
Deposit.Show();
}
public void btnWithdraw_Click(object sender, EventArgs e)
{
this.Hide();
frmWithdraw Withdraw = new frmWithdraw();
Withdraw.Show();
}
public void btnBalance_Click(object sender, EventArgs e)
{
this.Hide();
frmBalance Balance = new frmBalance();
Balance.Show();
}
}
New Account form (form to create object from the class)
public partial class frmNewAccount : Form
{
public frmNewAccount()
{
InitializeComponent();
}
private void btnRegister_Click(object sender, EventArgs e)
{
//Account newAccount = new Account();
string name = string.Copy(txtName.Text);
string accountNo = string.Copy(txtAccountNo.Text);
string accountType = string.Copy(txtAccountType.Text);
double amount = double.Parse(txtAmount.Text);
Account newAccount = new Account(name, accountNo, accountType, amount);
}
private Account btnMainMenu_Click(object sender, EventArgs e)
{
this.Hide();
frmMainMenu MainMenu = new frmMainMenu();
MainMenu.Show();
}
}
Deposit form
public partial class frmDeposit : Form
{
public frmDeposit()
{
InitializeComponent();
}
private void btnDeposit_Click(object sender, EventArgs e)
{
}
private void btnMainMenu_Click(object sender, EventArgs e)
{
this.Hide();
frmMainMenu MainMenu = new frmMainMenu();
MainMenu.Show();
}
}
what im trying to do here is create Account newAccount on New Account Form, using the data its created to be accessible in another form...

Answer 1

Your code has to be changed minimally to give this reference of an account to a child form. I would do it explicitly in constructor.
public partial class frmDeposit : Form
{
Account _account;
public frmDeposit(Account account)
{
_account = account;
InitializeComponent();
}
(...)
After this you can use inside the frmDeposit class the _account field.
This approach is typically better than using a property as you enforce the form to be initialized with an account.
And when you create your dialog to set deposit information, you will have to write instead of:
var depositForm = new frmDeposit(); //here you will get compilation error
depositForm.ShowDialog()
You will have to write:
var depositForm = new frmDeposit(account); //compilation error is fixed
depositForm.ShowDialog()

Answer 2

You usually don't pass classes, but instances (i.e. objects). Create an instance of the class in the form that starts your workflow. In every child form that's called, add a property
public BankAccount Account { get; set; }
and set the value of that property before showing the child form.
using (FrmChildForm frm = new FrmChildForm())
{
frm.Account = myBankAccount;
...
}
Another solution would be to create an instance variable in every child form as well and pass the account in the constructor:
using (FrmChildForm frm = new FrmChildForm(myBankAccount))
...
public class FrmChildForm : Form
{
private BankAccount _account;
public FrmChildForm(BankAccount theAccount)
{
_account = theAccount;
}
}
About your navigation
You're doing it wrong! You're filling up memory for nothing, creating instances over and over the place. Why?
Well, your main menu creates a child form, then hides itself. Your child form then generates a new main menu instead of just closing itself and showing the existing main form again! That's highly inefficient and prevents you from keeping the account instance I talked about above.
What you should do is this:
public void btnNewAccount_Click(object sender, EventArgs e)
{
frmNewAccount NewAccount = new frmNewAccount();
NewAccount.Account = myAccount;
NewAccount.FormClosing += SubFormClosing;
NewAccount.Show();
this.Hide();
}
Then, have a method SubFormClosing:
private void SubFormClosing(object sender, FormClosingEventArgs e)
{
this.Show();
}
Then, the code to return to the main form comes down to:
private void btnMainMenu_Click(object sender, EventArgs e)
{
this.Close();
}
This creates one main menu. Upon selecting an module, the module window is opened, the main menu is hidden. Instead of creating a new main menu when closing the module window, the old main menu is restored when the module window is closed.
The trick here is to attach an event handler to the closing event of the module form so the hidden menu form gets notified that it should show itself again.
And you should learn about modal dialogs. The "window" where a new account is created should actually be a modal dialog that collects the information. Then, the main menun sets its myAccount member variable based on the new account information. There's no need to pass the account to the "New Account" mask, as it creates a new account.