private void addButton_Click(object sender, EventArgs e) { string name = nameInput.Text; ; string state = stateInput.Text; var isNotNull = false; if (name.Trim() == "") { MessageBox.Show("Введите наименование гитары"); isNotNull = true; } else { isNotNull = false; } if (state.Trim() == "") { MessageBox.Show("Введите состояние гитары"); isNotNull = true; } else { isNotNull = false; } if (isNotNull) { ProductGuitarInfo guitar1 = new ProductGuitarInfo(name, state); ReadWriteFile file = new ReadWriteFile(); file.Write(guitar1.Name + "|" + guitar1.State, "Data"); guitar = guitar1; } }