JComboBox is a combination of a text field and a drop-down list that lets the user either type in a value or select it from a list that is displayed when the user clicks on the down arrow. The editing capability is disabled by default so that the component acts only as a drop down selectable list.

Notice that the JComboBox is created as a single unit. An array of Objects is passed to the constructor, or, Objects are added one at a time later on. The items in a JComboBox don't have to be Strings, they can be anything that is drawable.

JComboBox generates ItemEvents. When a new selection overrides a previous selection, two events are broadcast. It is up to the programmer to distinguish between ItemEvent.SELECTED events and ItemEvent.DESELECTED events.

[Reference: Topley, pp611-622]