-1
我試圖檢查一個開放的串行端口,將其從comboBox中刪除它,但是當我單擊comboBox下拉列表時,即使端口已關閉,我在線路上檢查到打開串行端口的異常。爲什麼會發生?請幫忙!這是我的代碼。異常說:發生了'System.NullReferenceException'。如果if條件爲真,則當serialport1打開時,則沒有例外。爲什麼?!爲什麼在檢查打開的串行端口時會出現異常?
private void comboBox9_DropDown(object sender, EventArgs e)
{
//Load Com Port List into comboBoxes when dropdown. Holds list actual
comboBox9.Items.Clear();
string[] portNames = SerialPort.GetPortNames(); //<-- Reads all available comPorts
foreach (var portName in portNames)
{
comboBox9.Items.Add(portName);
//Removes comboBox entry if port is Open
if (_serialPort1.IsOpen)
{
comboBox9.Items.Remove(_serialPort1.PortName);
}
}
}