[esquared]

If you choose a serial port that isn't valid in the Java program, it will close immediately with no error message. Make sure you are choosing a COM port that exists. Check it under My Computer, Properties, the Hardware Tab, Device Manager, Ports.

If you have a USB-Serial adapter, and it's working, you should see your COM port device listed in Ports. If you have a real serial port, it should also be listed under there.

--Eric