无法将“System.string”类型的对象转换为“....Event”类型

Question

I'm making a personal calendar/planner thing and I want to be able to click on an even in the list box and have it fill out the title and time forms. I've been searching through every forum post on similar issues but they usually just give more errors. Currently, when I click on the event in the list box, the program exits and just gives an Unhandled Exception error saying System.InvalidCastException: 'Unable to cast object of type 'System.String' to type 'ProjectName.Event'.'

This is the code that throws the error:

    private void LstEvents_SelectedIndexChanged(object sender, EventArgs e)
    {
        btnDelete.Enabled = true; // When something is selected, enable delete button

        Event eventtest = (Event)lstEvents.SelectedItem; // <--- This line throws error
        txtTitle.Text = eventtest.eventTitle.ToString();
    }

And this is my Event class:

public class Event
{
    int month, day, year, startHour, startMin, endHour, endMin;
    private DateTime startTime, endTime;
    public string eventTitle;

    public Event(int cMonth, int cDay, int cYear, int cStartHour, int cStartMin, int cEndHour, int cEndMin, string cEventTitle)
    {
        month = cMonth;
        day = cDay;
        year = cYear;
        startHour = cStartHour;
        startMin = cStartMin;
        endHour = cEndHour;
        endMin = cEndMin;
        eventTitle = cEventTitle;

        string tempDate = year.ToString() + "-" + month.ToString() + "-" + day.ToString() + " " + startHour.ToString() + ":" + startMin.ToString();
        startTime = DateTime.Parse(tempDate); // Convert startHour to DateTime

        tempDate = year.ToString() + "-" + month.ToString() + "-" + day.ToString() + " " + endHour.ToString() + ":" + endMin.ToString();
        endTime = DateTime.Parse(tempDate); // Do the same thing to endTime
    }

    public DateTime whenStartTime
    {
        get { return startTime; }
    }

    public DateTime whenEndTime
    {
        get { return endTime; }
    }

    public override string ToString()
    {
        return startTime.Year + "-" + startTime.Month + "-" + startTime.Day + " " + startTime.Hour + ":" + startTime.Minute; 
    }
}

Populating the list box:

    private void BtnAdd_Click(object sender, EventArgs e)
    {
        Event newEvent;

        newEvent = new Event(monthCalendar.SelectionStart.Month, monthCalendar.SelectionStart.Day, monthCalendar.SelectionStart.Year,
                             Convert.ToInt32(cboStartHour.SelectedItem), Convert.ToInt32(cboStartMinute.SelectedItem),
                             Convert.ToInt32(cboStopHour.SelectedItem), Convert.ToInt32(cboStopMinute.SelectedItem),
                             txtDescription.Text.ToString());

        form.lstEvents.Items.Add(newEvent.ToString());
    }

Answer 1

lstEvents.SelectedItem is a String; you want an Event. How you go from a String to an Event is going to depend on what that String is, and what class lstEvents is (and what other properties that class has).