How to Write an Item Listener

Item events are fired by components that implement the ItemSelectable interface. Generally, ItemSelectable components maintain on/off state for one or more items. The Swing components that fire item events include buttons like check boxes, check menu items, toggle buttons etc...and combo boxes.

Here is some item-event handling code taken from :

//where initialization occurs
public void itemStateChanged(ItemEvent e) {
    if (e.getStateChange() == ItemEvent.SELECTED) {
    } else {

The Item Listener API

The ItemListener Interface

Because ItemListener has only one method, it has no corresponding adapter class.

Method Purpose
itemStateChanged(ItemEvent) Called just after a state change in the listened-to component.

The ItemEvent Class

Method Purpose
Object getItem() Returns the component-specific object associated with the item whose state changed. Often this is a String containing the text on the selected item.
ItemSelectable getItemSelectable() Returns the component that fired the item event. You can use this instead of the getSource method.
int getStateChange() Returns the new state of the item. The ItemEvent class defines two states: SELECTED and DESELECTED.

Examples that Use Item Listeners

The following table lists some examples that use item listeners.

Example Where Described Notes
ComponentEventDemo This section and How to Write a Component Listener Listens for item events on a check box, which determines whether a lable is visible.
CheckBoxDemo How to Use Check Boxes Four check boxes share one item listener, which uses getItemSelected to determine which check box fired the event.
MenuDemo How to Use Menus Listens for item events on a check box menu item.
MenuDemo How to Use Scroll Panes Listens for item events on a toggle button.