Professional Android 4 Application Development

382 x CHAPTER 10 EXPANDING THE USER EXPERIENCE
‰ Icons — Icons are displayed only in the icon menu or as an action; they are not visible
in the extended menu or submenus. You can specify any Drawable resource as a menu
icon.
menuItem.setIcon(R.drawable.menu_item_icon);
‰ Menu item click listener — An event handler that will execute when the Menu Item is
selected. For efficiency, the use of such an event handler is discouraged; instead, Menu Item
selections should be handled by the onOptionsItemSelected handler, as shown in the
“Handling Menu Selections” section later in this chapter.
menuItem.setOnMenuItemClickListener(new OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem _menuItem) {
[ ... execute click handling, return true if handled ... ]
return true;
}
});
‰ Intents — An Intent assigned to a Menu Item is triggered when a Menu Item click isn’t
handled by a MenuItemClickListener or the Activity’s onOptionsItemSelected handler.
When the Intent is triggered, Android will execute startActivity, passing in the specified
Intent.
menuItem.setIntent(new Intent(this, MyOtherActivity.class));
Adding Action Views and Action Providers
The introduction of actions and the Action Bar in Android 3.0 (API level 11) made it possible to add
richer interaction modes to the menu system. In particular, it’s now possible to add interactive Views
to your Action Bar actions in the form of action Views and Action Providers.
You can replace the icon/text used to represent an action with any View or layout using the Menu
Item’s setActionView method, passing in either a View instance or a layout resource, as shown in
Listing 10-13.
LISTING 10-13: Adding an action View
menuItem.setActionView(R.layout.my_action_view)
.setShowAsActionFlags(MenuItem.SHOW_AS_ACTION_IF_ROOM|
MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW);
code snippet PA4AD_Ch10_ActionBar/src/ActionBarActivity.java
Once added, the action View will be displayed whenever the associated Menu Item is displayed as
an action in the Action Bar, but will never be displayed if the Menu Item is relegated to the overflow
menu.
A better alternative, introduced in Android 4.0 (API level 14), is to add the MenuItem.SHOW_AS_
ACTION_COLLAPSE_ACTION_VIEW flag. When this flag is set, the Menu Item will be represented using