all errorproviders do not function properly

Question

hi i am working on my college project on Visual Studio 2010 C#. I have a WinForms application which has 8 textboxes. Whenever the user leaves the textbox empty, the error icon should pop up and a label besides it should be made visible displaying the error message.

When I execute the code below only the first two error providers work. The rest do not show up.

Could anyone help me?

private void textBox1_Leave(object sender, EventArgs e)
{
    if (String.IsNullOrEmpty(textBox1.Text))
    {
        errorProvider1.SetError(textBox1,"REQUIRED FIELD");
        label12.Text = "REQUIRED FIELD";
    }
    else
    {
        errorProvider1.Dispose();
    }
 }

 private void textBox2_Leave(object sender, EventArgs e)
 {
     monthCalendar1.Visible = false;
     if (String.IsNullOrEmpty(textBox2.Text))
     {
         errorProvider2.SetError(textBox2,"REQUIRED FIELD");
         label13.Text = "REQUIRED FIELD";
     }
     else
     {
         errorProvider2.Dispose();
     }
 }

 private void textBox3_Leave(object sender, EventArgs e)
 {

     if (textBox3.Text=="")
     {
         errorProvider3.SetError(textBox3, "REQUIRED FIELD");
         label14.Text = "REQUIRED FIELD";
     }
     else
     {
         errorProvider3.Dispose();
     }
  }

  private void textBox4_Leave(object sender, EventArgs e)
  {
      monthCalendar1.Visible = false;
      if (String.IsNullOrEmpty(textBox4.Text))
      {
          errorProvider4.SetError(textBox4, "REQUIRED FIELD");
          label15.Text = "REQUIRED FIELD";
      }
      else
      {
          errorProvider4.SetError(textBox4, "");
      }
  }

  private void textBox5_Leave(object sender, EventArgs e)
  {

      if (String.IsNullOrEmpty(textBox5.Text))
      {
          errorProvider5.SetError(textBox5, "REQUIRED FIELD");
          label16.Text = "REQUIRED FIELD";
      }
      else
      {
          errorProvider5.SetError(textBox5, "");
      }
  }

  private void textBox6_Leave(object sender, EventArgs e)
  {
      monthCalendar2.Visible = false;
      if (String.IsNullOrEmpty(textBox6.Text))
      {
          errorProvider6.SetError(textBox6, "REQUIRED FIELD");
          label17.Text = "REQUIRED FIELD";
      }
      else
      {
          errorProvider6.SetError(textBox6, "");
      }
  }

Answer 1

You dispose your error provider whenever someone inputs text in the text box. Disposing an object frees all resources and prevents further usage.

Use the Clear() method of the error provider instead. This will clear all errors. If you want to clear only a single error, set an empty text.

And - usually - you do need only one error provider per Form.

private void textBox1_Leave(object sender, EventArgs e)
{
    if (String.IsNullOrEmpty(textBox1.Text))
    {
                     errorProvider.SetError(textBox1,"REQUIRED FIELD");
                     label12.Text = "REQUIRED FIELD";
    }
    else
    {
        errorProvider.SetError(textBox1, String.Empty); // to clear only the error for this text box
        // errorProvider.Clear(); // to clear all errors for this provider
    }
}

EDIT: provided fully working example

This is reduced to handling the error provider. Whenever the cursor leaves a text field, this field is check for contents. If empty, the error is shown. The user needs to return to the field, enter dta and leave again to clear the error. This is basically what you defined as requirement in your example. I left out switching the label text, but that does not seem to be the problem.

To check out, create a new WinForm-Application and replace the class Form1 with this code. For brevity, i included the InitialiseComponent() code in the constructor, so probably VS will not show the form (at least VS2010 doesn't show it correctly).

public partial class Form1 : Form
{
    public Form1()
    {
        this.components = new System.ComponentModel.Container();
        this.errorProvider1 = new ErrorProvider(this.components);
        this.textBox1 = new TextBox();
        this.textBox2 = new TextBox();
        ((System.ComponentModel.ISupportInitialize)(this.errorProvider1)).BeginInit();
        this.SuspendLayout();
        // 
        // errorProvider1
        // 
        this.errorProvider1.ContainerControl = this;
        // 
        // textBox1
        // 
        this.textBox1.Location = new System.Drawing.Point(42, 25);
        this.textBox1.Name = "textBox1";
        this.textBox1.Size = new System.Drawing.Size(100, 20);
        this.textBox1.TabIndex = 0;
        this.textBox1.Leave += this.textBox1_Leave;
        // 
        // textBox2
        // 
        this.textBox2.Location = new System.Drawing.Point(42, 52);
        this.textBox2.Name = "textBox2";
        this.textBox2.Size = new System.Drawing.Size(100, 20);
        this.textBox2.TabIndex = 1;
        this.textBox2.Leave += this.textBox2_Leave;
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(284, 262);
        this.Controls.Add(this.textBox2);
        this.Controls.Add(this.textBox1);
        this.Name = "Form1";
        this.Text = "Form1";
        ((System.ComponentModel.ISupportInitialize)(this.errorProvider1)).EndInit();
        this.ResumeLayout(false);
        this.PerformLayout();
    }

    private void textBox1_Leave(object sender, System.EventArgs e)
    {
        if (string.IsNullOrEmpty(textBox1.Text)) {
            errorProvider1.SetError(textBox1, "REQUIRED FIELD");
        }
        else {
            errorProvider1.SetError(textBox1, string.Empty);
        }
    }

    private void textBox2_Leave(object sender, System.EventArgs e)
    {
        if (string.IsNullOrEmpty(textBox2.Text))
        {
            errorProvider1.SetError(textBox2, "REQUIRED FIELD");
        }
        else
        {
            errorProvider1.SetError(textBox2, string.Empty);
        }
    }
}