(1)Preference是什么?
Represents the basic Preference UI building block displayed by a PreferenceActivity
in the form of a ListView
.
(2)它能干什么?
This class provides the View
to be displayed in the activity and associates with a SharedPreferences
to store/retrieve the preference data.
(3)怎么做的?
When specifying a preference hierarchy in XML, each element can point to a subclass of Preference
, similar to the view hierarchy and layouts.
This class contains a key
that will be used as the key into the SharedPreferences
. It is up to the subclass to decide how to store the value.
下面我们对它进行分析:
/**
* Gets the View that will be shown in the {@link PreferenceActivity}.
*
* @param convertView The old View to reuse, if possible. Note: You should
* check that this View is non-null and of an appropriate type
* before using. If it is not possible to convert this View to
* display the correct data, this method can create a new View.
* @param parent The parent that this View will eventually be attached to.
* @return Returns the same Preference object, for chaining multiple calls
* into a single statement.
* @see #onCreateView(ViewGroup)
* @see #onBindView(View)
*/
public View getView(View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = onCreateView(parent);
}
onBindView(convertView);
return convertView;
}