Java Swing

The JComboBox Class

JComboBox is the Swing version of a combo box component. It is very similar to the AWT Choice component, and even implements the ItemSelectable interface for backward compatibility. By default, the JComboBox component provides a single text edit field adjacent to a small button with a downward arrow. When the button is pressed, a popup list of choices is displayed below the text edit field, one of which can be selected by the user. If a selection is made, the choice is copied into a text edit field and the popup disappears. If there was a previous selection, it is erased. You can also remove the popup by pressing the TAB key while the combo box has the focus. Figure 7.11 shows combo boxes for three look-and-feels.

Figure 7-11. The JComboBox component in the three look-and-feels

The text field in the JComboBox component can have one of two states: editable or static. This state is given by the editable property. If the text field is editable, the user is allowed to type information into the text box, as well as make selections from the list. If the component is not editable, the user can only make selections from the list.

Unless you specify a set of objects in the constructor, the combo box comes up empty. You can use the addItem() method to add objects to the combo box list. Conversely, the removeItem() and removeItemAt() methods remove a specified object ...