identify usb port

[shawn peter]

i need to write programm to usb port when someone plug flash to it.but problem is there are four usb ports in my computer.
and time to time it changes the drive letter of pluged usb drive.how to overcome this.i need to get the drive letter of usb drive
when flash drive plug to it

[Arun Kumar]

from a cross read it feels like its going to be a virus,

https://coderanch.com/t/433336/Java-General-advanced/java/Virus

what is the actual need to " write programm to usb port when someone plug flash to it"