If you are using enum which is the smart way to do things and also using a jframe then you don't really need a default combo box model. You can just set your combo box to your enum.
Let's say you only want a person to choose a location based off your enum and no other option. I rather tell you to use a joptionpane. It's pretty much a simple pip up box and depending if it's a yes or no question, or a blank field for someone to type in. Or even better a combo box. It includes a cancel and ok button.
It's pretty simple for the basic needs. All you need to do is make the option return the data type you need: string, int, enum variable.