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Franco Torres
Asked: 2020-08-20 08:02:16 +0800 CST 2020-08-20 08:02:16 +0800 CST

How to avoid ObjectDisposedException in C#

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when I try to reopen a form that was closed from the X of the window I get the exception System.ObjectDisposedExceptionwith the message "Cannot access the discarded object. Object name: 'frm_schedules'."

I understand that X calls the method Dispose(), which releases resources, but I don't know to what extent it releases. I check that the form is not Nullwhen I call it, but it keeps throwing that exception.

Code of the form frm_horarios, is what I call:

public partial class frm_horarios : Form
    {
        private static Form instancia = null;  //implemento el patron singleton para tener solo una instancia de este formulario

        private frm_horarios()
        {
            InitializeComponent();
        }

        public static Form getFormularioHorario()
        {
            if(instancia ==null)
            {
                instancia = new frm_horarios();
                return instancia;
            }
            else
            {
                return instancia;
            }
        }
    }

Code of the button that calls the form frm_hours:

private void btn_horarios_Click(object sender, EventArgs e)
        {
            if(horario !=null)//la variable horario es del tipo Form y se encuentra declarada en el principio de la clase
            {
                horario.Show();
            }          
            else
            {
                horario = frm_horarios.getFormularioHorario();
                horario.Show();
            }
        }
c#

1 Answers

  1. Best Answer

    You can prevent the form closure from frm_horariosactually disposing of the object. To do this, you can add an event FormClosing:

    private void frm_horarios_FormClosing(object sender, FormClosingEventArgs e)
{
    e.Cancel = true; // Cancelas el evento de cerrado
    this.Hide();     // Ocultas el formulario sin desecharlo
}

    Another way to do this would be to open the child form as a dialog , by changing just one line of your code:

    private void btn_horarios_Click(object sender, EventArgs e)
{
    // Con menos líneas puedes obtener el mismo resultado:
    if (horario == null)
        horario = frm_horarios.getFormularioHorario();
    horario.ShowDialog(this);
    //      ^ En lugar del método "Show", usar ShowDialog
}
    • 2