private void findPorts() {
        portComboBox.addItem("-");
        Enumeration portList = CommPortIdentifier.getPortIdentifiers();
        while (portList.hasMoreElements()) {
            CommPortIdentifier portId = (CommPortIdentifier) portList.nextElement();
            String name = portId.getName();
            if (name.substring(0, 3).equals("COM")) {
                tableOfPorts.put(name, portId);
                portComboBox.addItem(name);
            }
        }
    }