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Problem with adding item to the list from another form

I would like to click "add button" to add contacts to the list of contacts in ClientApp, but nothing added to box, only to a list named users.
I want to see new usser nickname on the listbox. But when I evokes function AddContact from other form I don't see new usser on the listbox, from this same is good.
In atributes I see this cell, named "dwa".
Someone will help?
AddUsser:
public partial class NewUser: Form
{
...
public void New()
{
ClientApp.users.Add(new accounts(textBox1.Text, textBox2.Text));
ClientApp x = new KlientApp();
x.AddContact(textBox2.Text);
this.Hide();
}
}
ClientApp:
public partial class ClientApp: Form
{
...
public void AddContact(string nick)
{
contacts.BeginUpdate();
contacts.Items.Add(nick);
contacts.EndUpdate();
}
}
enter image description here
To Gellio Gao.
I sew ObjectDisposedException in private void Msg when I close program on go:
private void ShowMsg()
{
bool temp = true;
while( temp == true)
{
if(DateTime.Now.Second % 3 == 0)
{
Msg();
showed.WaitOne();
showed.Reset();
showed.WaitOne(1000);
}
}
}
private void Msg()
{
ClientLog.send_msg= "Wyswietl wiadomosci";
ClientLog.received.Reset();
Thread wątek = new Thread(new ThreadStart(AsynchronousClient.StartClient));
wątek.IsBackground = true;
wątek.Start();
ClientLog.received.WaitOne();
Invoke(new Action(() =>
{
if (ClientLog.send_msg!= "")
{
messages.AppendText(ClientLog.send_msg+ Environment.NewLine);
}
}));
showed.Set();
}

You should pass an instance of ClientApp to NewUser instead of creating a new instance inside of NewUser. Something like:
public partial class NewUser: Form
{
private ClientApp _client;
public NewUser(ClientApp client)
{
this._client = client;
}
................
public void New()
{
ClientApp.users.Add(new accounts(textBox1.Text, textBox2.Text));
this._client.AddContact(textBox2.Text);
this.Hide();
}
}
Update: Give a sample of using this._client.

Passing string between forms returns null

In the program you enter with a username brought from a database. I need to pass that username to another form but when I do it, it returns null in the second form although in the first form it appears.( "Jugador" is the class from where I bring the name).
public Usuario()
{
InitializeComponent();
}
private string _Message;
public string Message
{
get { return _Message; }
set { _Message = strName; }
}
public string strName;
private void button1_Click(object sender, EventArgs e)
{
if (textBox1.Text!="")
{
Jugador jug = new Jugador();
jug.Traemelo(textBox1.Text);
strName = textBox1.Text;
elegirTipo us = new elegirTipo();
us.Show();
this.Hide();
}
}
And in my other form i have this.(Usuario is the first form)
private void silabas_Load(object sender, EventArgs e)
{
Usuario usu = new Usuario();
juga.Traemelo(usu.Message);
}
I've got to add that in the middle of these forms I pass by one but doens't need the variable there.
Thanks for the help! I really don't know what is happening because I've done this other times.

// Usuario.cs
public string Message { get; set; }
...
Silabas silabas = new Silabas(this);
// Silabas.cs
public Silabas(Usuario usuario)
{
// Here you can access the usuario.Message
}

What I personally would do is to create a static class and hold the values in it. This would also let me not to instantiate the class every time I need to use it.
public static class Jugador
{
//ctor if needed
public static string Username { get; set; }
}
Now, in your code where you both set or get the values of the username:
//login process
Jugador.Username = "some username";
//in application (get)
textbox1.Text = Jugador.Username;
I believe this is what you are looking for.

At a first glance:
public string Message
{
get { return _Message; }
set { _Message = value } // instead of strName;
}
no Message=something (set is never called)
_Message seems to compete with strName. One variable should be enough.
EDIT: Combined to this:
public Usuario()
{
InitializeComponent();
}
private string _Message;
public string Message
{
get { return _Message; }
set { _Message = value; }
}
private void button1_Click(object sender, EventArgs e)
{
if (!string.IsNullOrEmpty(textBox1.Text))
{
Jugador jug = new Jugador();
jug.Traemelo(textBox1.Text);
Message = textBox1.Text;
elegirTipo us = new elegirTipo();
us.Show();
this.Hide();
}
}

Problem is since you are creating a new instance i.e. Usuario usu = new Usuario(); of the object in the other class, the value becomes null. I would use a static variable. In your Usuario class use
public static string strName{get;set;}
Now to set the value say Usuario.strName = textBox1.Text;
in your other class here say,
private void silabas_Load(object sender, EventArgs e)
{
juga.Traemelo(Usuario.strName);
}

How to find items in a ListBox?

I am creating an application where I have a ListBox which has items that are read in from a text file using StreamReader. I have created a search form but I'm not sure what to do next. Can anyone give me some suggestions please? Here is my code:
My code for the ListBox (sorry it's so long)
public partial class frmSwitches : Form
{
public static ArrayList switches = new ArrayList();
public static frmSwitches frmkeepSwitches = null;
public static string inputDataFile = "LeckySafe.txt";
const int numSwitchItems = 6;
public frmSwitches()
{
InitializeComponent();
frmkeepSwitches = this;
}
private void btnDevices_Click(object sender, EventArgs e)
{
frmDevices tempDevices = new frmDevices();
tempDevices.Show();
frmkeepSwitches.Hide();
}
private bool fileOpenForReadOK(string readFile, ref StreamReader dataIn)
{
try
{
dataIn = new StreamReader(readFile);
return true;
}
catch (FileNotFoundException notFound)
{
MessageBox.Show("ERROR Opening file (when reading data in) - File could not be found.\n"
+ notFound.Message);
return false;
}
catch (Exception e)
{
MessageBox.Show("ERROR Opening File (when reading data in) - Operation failed.\n"
+ e.Message);
return false;
}
}
private bool getNextSwitch(StreamReader inNext, string[] nextSwitchData)
{
string nextLine;
int numDataItems = nextSwitchData.Count();
for (int i = 0; i < numDataItems; i++)
{
try
{
nextLine = inNext.ReadLine();
if (nextLine != null)
nextSwitchData[i] = nextLine;
else
{
return false;
}
}
catch (Exception e)
{
MessageBox.Show("ERROR Reading from file.\n" + e.Message);
return false;
}
}
return true;
}
private void readSwitches()
{
StreamReader inSwitches = null;
Switch tempSwitch;
bool anyMoreSwitches = false;
string[] switchData = new string[numSwitchItems];
if (fileOpenForReadOK(inputDataFile, ref inSwitches))
{
anyMoreSwitches = getNextSwitch(inSwitches, switchData);
while (anyMoreSwitches == true)
{
tempSwitch = new Switch(switchData[0], switchData[1], switchData[2], switchData[3], switchData[4], switchData[5]);
switches.Add(tempSwitch);
anyMoreSwitches = getNextSwitch(inSwitches, switchData);
}
}
if (inSwitches != null) inSwitches.Close();
}
public static bool fileOpenForWriteOK(string writeFile, ref StreamWriter dataOut)
{
try
{
dataOut = new StreamWriter(writeFile);
return true;
}
catch (FileNotFoundException notFound)
{
MessageBox.Show("ERROR Opening file (when writing data out)" +
"- File could not be found.\n" + notFound.Message);
return false;
}
catch (Exception e)
{
MessageBox.Show("ERROR Opening File (when writing data out)" +
"- Operation failed.\n" + e.Message);
return false;
}
}
public static void writeSwitches()
{
StreamWriter outputSwitches = null;
if (fileOpenForWriteOK(inputDataFile, ref outputSwitches))
{
foreach (Switch currSwitch in switches)
{
outputSwitches.WriteLine(currSwitch.getSerialNo());
outputSwitches.WriteLine(currSwitch.getType());
outputSwitches.WriteLine(currSwitch.getInsDate());
outputSwitches.WriteLine(currSwitch.getElecTest());
outputSwitches.WriteLine(currSwitch.getPatId());
outputSwitches.WriteLine(currSwitch.getNumDevice());
}
outputSwitches.Close();
}
if (outputSwitches != null) outputSwitches.Close();
}
private void showListOfSwitches()
{
lstSwitch.Items.Clear();
foreach (Switch b in switches)
lstSwitch.Items.Add(b.getSerialNo()
+ b.getType() + b.getInsDate()
+ b.getElecTest() + b.getPatId() + b.getNumDevice());
}
My code for the search form:
private void btnSearch_Click(object sender, EventArgs e)
{
frmSearchSwitch tempSearchSwitch = new frmSearchSwitch();
tempSearchSwitch.Show();
frmkeepSwitches.Hide();
}

If using a List<T> and lambda is not possible for you then go no farther.
Here I use a List<T> for the data source of a ListBox and mocked up data as where the data comes from is not important but here I am focusing on searching on a property within a class where a select is used to index the items then the where searches in this case) for a specific item, if found the index is used to move to the item. No code present for if not located as this is easy for you to do if the code here is something that is doable for you.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
namespace ListBoxSearch_cs
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Button1_Click(object sender, EventArgs e)
{
var results =
((List<Item>)ListBox1.DataSource)
.Select((data, index) => new
{ Text = data.SerialNumber, Index = index })
.Where((data) => data.Text == "BB1").FirstOrDefault();
if (results != null)
{
ListBox1.SelectedIndex = results.Index;
}
}
private void Form1_Load(object sender, EventArgs e)
{
var items = new List<Item>() {
new Item {Identifier = 1, SerialNumber = "AA1", Type = "A1"},
new Item {Identifier = 2, SerialNumber = "BB1", Type = "A1"},
new Item {Identifier = 3, SerialNumber = "CD12", Type = "XD1"}
};
ListBox1.DisplayMember = "DisplayText";
ListBox1.DataSource = items;
}
}
/// <summary>
/// Should be in it's own class file
/// but done here to keep code together
/// </summary>
public class Item
{
public string SerialNumber { get; set; }
public string Type { get; set; }
public int Identifier { get; set; }
public string DisplayText
{
get
{
return SerialNumber + " " + this.Type;
}
}
}
}

Windows Form Not Returning Correct Value from Public Method

I have three classes, code provided below.
Network - Add and Remove Phone, Process Calls
Phone1 and Phone2 can call each other when added to the network.
But I am having issue when I am connecting both phone to the network and trying to call phone1 to phone2, it is keep giving me "receiver busy". I have tried to do little debugging and read status of phone2 when calling from phone1 but it returns an empty string (Which should actually return "A", when it is added to the network).
Any help would much appreciated.
-----Networks Class------------------
namespace Demo
{
public partial class network : Form
{
phone1 p1 = new phone1();
phone2 p2 = new phone2();
public network()
{
InitializeComponent();
}
public Boolean numberValidator(int number)
{
Boolean exist = false;
if (comboBox2.Items.Equals(number))
{
exist = true;
}
return exist;
}
public void processCall(int rNumber)
{
if (!numberValidator(rNumber))
{
p1.TextBox1.Clear();
p1.TextBox1.Text = "Not connected";
//MessageBox.Show(p2.returnPhoenStatus());
}
else
{
p1.TextBox1.Clear();
p1.TextBox1.Text = "Call in progress";
p2.receiveCall(1);
p1.setStatus("Busy");
/*
if (p2.btnCallPressStatus())
{
p1.TextBox1.Clear();
p1.TextBox1.Text = "Call initiated";
}*/
}
}
private void button1_Click(object sender, EventArgs e)
{
if (comboBox1.SelectedIndex == 0)
{
p1.Show();
comboBox2.Items.Add(1);
p1.setStatus("A");
}
if (comboBox1.SelectedIndex == 1)
{
p2.Show();
comboBox2.Items.Add(2);
p2.setStatus("A");
}
}
}
}
----------Phone1 Class---------
namespace Demo
{
public partial class phone1 : Form
{
public phone1()
{
InitializeComponent();
}
string status;
public void setStatus(string Status)
{
status = Status;
}
public string returnStatus()
{
return status;
}
public void receiveCall(int callerNumber)
{
setStatus("Busy");
btnCall.Text = "Answer";
textBox1.Text = "Phone " + callerNumber + " Calling.";
}
public void makeCall(int number)
{
phone2 p2 = new phone2();
network net = new network();
MessageBox.Show(p2.returnStatus()); // this line not returing status of phone2
if (p2.returnStatus() == "A")
{
net.processCall(number);
}
else
{
textBox1.Text = "Receiver Busy";
}
}
public TextBox TextBox1
{
get
{
return textBox1;
}
}
private void btnCall_Click(object sender, EventArgs e)
{
string number = textBox1.Text;
int numberInt = Convert.ToInt16(number);
makeCall(numberInt);
}
string phoneNo = "";
private void btn2_Click(object sender, EventArgs e)
{
phoneNo = phoneNo + btn2.Text;
textBox1.Text = phoneNo;
}
}
}
-------------phone2 Class--------------
namespace Demo
{
public partial class phone2 : phone1
{
public phone2()
{
InitializeComponent();
}
}
}

I think you are setting the status of P1 both the times. Check this if condition in button1_Click method in network class. The setStatus should be for P2.
if (comboBox1.SelectedIndex == 1)
{
p2.Show();
comboBox2.Items.Add(2);
p2.setStatus("A");
}

Piyush has the right answer, but I thought I'd add this answer as a handy hint to avoid this kind of error.
Try writing your button1_Click method like this:
private void button1_Click(object sender, EventArgs e)
{
var i = comboBox1.SelectedIndex;
var p = (new [] { p1, p2 })[i]; // Or `var p = i == 0 ? p1 : p2;`
p.Show();
comboBox2.Items.Add(i + 1);
p.setStatus("A");
}
This way you avoid the code duplication and the mistyping that occurred.

Access TextBox from Static method in C#?

I have 2 classes: MyForm and Database
In MyForm I have a method to change a label text to show error:
public void printError(string text){
label1.Text = text;
}
My Database class needs to access that method too, so I make it static:
public static void printError(MyForm form, string text){
form.label1.Text = text;
}
Now the problem is, how do I call that method from Database class?
This question I found said that I need to pass MyForm into Database's contructor like this:
class MyForm : Form{
Database db;
public Form(){
db = new Database(this);
}
}
class Database{
MyForm form;
public Database(MyForm f){
form = f;
}
...
//then I can access the printError like this
MyForm.printError(form, "You got error");
}
I tried that and it freezes the form. Any other solution?
Thanks

Here is a very simple example of how you can achieve this without your data layer knowing about your UI:
class MyForm : Form
{
Database db;
public Form()
{
db = new Database(this);
}
public void DoSomething()
{
var errors = db.Login("", "");
if (errors.Any())
label1.Text = errors.First(); // Or you can display all all of them
}
}
class Database
{
public List<string> Login(string username, string password)
{
var errors = new List<string>();
if (string.IsNullOrEmpty(username))
errors.Add("Username is required");
if (string.IsNullOrEmpty(password))
errors.Add("Password is required");
[...]
return errors;
}
}

Like #Matthew Ferreira and others have stated the design is not idea, but here's something to get you started.
class MyForm : Form
{
public void SomeMethod()
{
var dataAccess = new Repository();
dataAccess.ExecuteQuery();
if (dataAccess.Exceptions.Any())
{
// display your error messages
form.label1.Text = dataAccess.Exceptions.Select(x => x.ToString());
}
}
}
class Repository
{
private readonly HashSet<Exception> _exceptions = new HashSet<Exception>();
public IEnumerable<Exception> Exceptions
{
get { return _exceptions; }
}
public int ExecuteQuery()
{
var numberOfRecordsAffected = 0;
try
{
// do something
}
catch (Exception ex)
{
// normall catching exceptions is a bad idea
// and you should really catch the exception at the
// layer best equiped to deal with it
_exceptions.Add(ex);
}
// but, for the purpose of this example we might want to add some logic to try the query on another database ????
try
{
// do something
}
catch (Exception ex)
{
_exceptions.Add(ex);
}
return numberOfRecordsAffected;
}
}

You need to look up "seperation of concerns". Its really bad to mix your UI code with you Database Access Layer (DAL). Better to bind the UI to business objects that are populated via a DAL.
To let the UI know about an error you could simply use a delegate.
namespace OperationErrorDelegate
{
public delegate void OperationErrorHandler(Exception ex);
public class DAL
{
public event OperationErrorHandler ReportError;
public void DoDALOperationThatCausesError()
{
try
{
int i = 1;
int j = 0;
int k = i/j;
}
catch (Exception ex)
{
ReportError(ex);
}
}
}
}
Add this code to the form:
using System ;
using System.Windows.Forms;
namespace OperationErrorDelegate
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
DAL DAL = new DAL();
DAL.ReportError += new OperationErrorHandler(DAL_OperationErrorProgress);
DAL.DoDALOperationThatCausesError();
}
private void DAL_OperationErrorProgress(Exception ex)
{
label1.Text = ex.Message;
}
}
}

Assuming the OP's requirement is to display an error message in a label, when the credentials are wrong:
private void btn_login_Click(object sender, EventArgs e)
{
MySqlConnection con = new MySqlConnection("server=localhost;uid=root;password=abc;database=mydb");
MySqlCommand cmd = new MySqlCommand("select * from emp where name='" + textBox1.Text + "'and pwd='" + textBox2.Text + "'",con);
con.Open();
MySqlDataReader dr = cmd.ExecuteReader();
if (dr.Read())
{ //successful
//navigate to next page or whatever you want
}
else
Label1.Text("Invalid userid or password");
con.Close();
}
And if you need error message for wrong data type (the user input string but the database column is Integer), then use validations at client side. You dont need to do it at backend, since that will be a burden.
You can use regular expressions for that in the button_click itself.