Professional Android 4 Application Development

388 x CHAPTER 10 EXPANDING THE USER EXPERIENCE
Using Context Menus and Popup Menus
Context Menus are contextualized by the currently focused View and are triggered when a user
long-presses the trackball, middle D-pad button, or a View (typically for approximately 3 seconds).
A Context Menu is displayed as a floating window above your Activity.
Android 3.0 (API level 11) introduced the PopupMenu class, a lighter-weight alternative to the
ContextMenu that anchors itself to a specific View.
You define and populate Context Menus and Popup Menus as you define and populate Activity
Menus. There are two options available for creating Context Menus for a particular View.
Creating Context Menus
One option is to create a generic ContextMenu object for a View class by overriding a View’s
onCreateContextMenu handler, as shown here:
@Override
public void onCreateContextMenu(ContextMenu menu) {
super.onCreateContextMenu(menu);
menu.add(“ContextMenuItem1”);
}
The Context Menu created here will be available within any Activity that includes this View class.
The more common alternative is to create Activity-specific Context Menus by overriding the
Activity’s onCreateContextMenu method, and registering the Views that should use it using the
registerForContextMenu method, as shown in Listing 10-19.
LISTING 10-19: Assigning a Context Menu to a View
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
EditText view = new EditText(this);
setContentView(view);
}
registerForContextMenu(view);
code snippet PA4AD_Ch10_ActionBar/src/ActionBarActivity.java
Once a View has been registered, the onCreateContextMenu handler will be triggered the first time
a Context Menu is displayed for that View.
To populate the Context Menu parameter with the appropriate Menu Items, override onCreate
ContextMenu and check which View has triggered the menu creation.
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);