private void btnEdit_Click(object sender, EventArgs e) { if (dgvStudents.SelectedRows.Count == 0) { return; } var selectedRow = dgvStudents.SelectedRows[0]; Student selectedStudent = _studentList.Find(Convert.ToInt32(selectedRow.Cells[0].Value)); var editForm = new OneStudentForm(OneStudentForm.WorkMode.EditStudent, selectedStudent); Student newStudent = editForm.ShowDialog(); _studentList.Replace(selectedStudent.StudentId, newStudent); _studentList.Update(); dgvStudents.DataSource = typeof(List <Student>); dgvStudents.DataSource = _studentList.Value; }