Android™ Application Development - Bahar Ali Khan

}
super.onCreate(icicle);
CompassView cv = new CompassView(this);
setContentView(cv);
cv.setBearing(45);
Chapter 4: Creating User Interfaces
To use the same control within a layout resource, specify the fully qualifi ed class name when you create
a new node in the layout defi nition, as shown in the following XML snippet:
You can infl ate the layout and get a reference to the CompassView as normal, using the following code:
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
CompassView cv = (CompassView)this.findViewById(R.id.compassView);
cv.setBearing(45);
}
Creating and Using Menus
Menus offer a way to expose application functions without sacrifi cing valuable screen space. Each
Activity can specify its own Activity menu that’s displayed when the device’s menu button is pressed.
Android also supports context menus that can be assigned to any View within an Activity. A View’s
context menu is triggered when a user holds the middle D-pad button, depresses the trackball, or longpresses
the touch screen for around 3 seconds when the View has focus.
Activity and context menus support submenus, checkboxes, radio buttons, shortcut keys, and icons.
Introducing the Android Menu System
If you’ve ever tried to navigate a mobile phone menu system using a stylus or trackball, you’ll know
that traditional menu systems are awkward to use on mobile devices.
To improve the usability of application menus, Android features a three-stage menu system optimized
for small screens:
The Icon Menu
❑ This compact menu (shown in Figure 4-4) appears along the bottom of the
screen when the Menu button is pressed. It displays the icons and text for up to six Menu Items
(or submenus).
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