【起航计划 030】2015 起航计划 Android APIDemo的魔鬼步伐 29 App->Preferences->Preferences from code

这里我们使用类比的方法，将 PreferenceActivity 与一般的Activity 作个类比，可以更好的理解Android.Preference中的各个类。

PreferenceActivity	Activity
Preference	View
PreferenceGroup	ViewGroup
PreferenceScreen	LinearLayout
CheckBoxPreference	CheckBox
EditTextPreference	EditText
ListPreference	List
PreferenceCategory	ViewGroup
…	..

PreferenceActivity 的UI是通过Preference等来定义，和Activity的ContentView一样，PreferenceActivity 的UI可以通过XML定义，也可以使用代码来定义，本例就是使用代码来定义PreferenceActivity 的UI。部分代码如下：

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

PreferenceScreen root = getPreferenceManager().createPreferenceScreen(this);
setPreferenceScreen(root);
populatePreferenceHierarchy(root);
}

private void populatePreferenceHierarchy(PreferenceScreen root) {
// Inline preferences
PreferenceCategory inlinePrefCat = new PreferenceCategory(this);
inlinePrefCat.setTitle(R.string.inline_preferences);
root.addPreference(inlinePrefCat);

// Checkbox preference
CheckBoxPreference checkboxPref = new CheckBoxPreference(this);
checkboxPref.setKey("checkbox_preference");
checkboxPref.setTitle(R.string.title_checkbox_preference);
checkboxPref.setSummary(R.string.summary_checkbox_preference);
inlinePrefCat.addPreference(checkboxPref);

// Switch preference
SwitchPreference switchPref = new SwitchPreference(this);
switchPref.setKey("switch_preference");
switchPref.setTitle(R.string.title_switch_preference);
switchPref.setSummary(R.string.summary_switch_preference);
inlinePrefCat.addPreference(switchPref);

// Dialog based preferences
PreferenceCategory dialogBasedPrefCat = new PreferenceCategory(this);
dialogBasedPrefCat.setTitle(R.string.dialog_based_preferences);
root.addPreference(dialogBasedPrefCat);

// Edit text preference
EditTextPreference editTextPref = new EditTextPreference(this);
editTextPref.setDialogTitle(R.string.dialog_title_edittext_preference);
editTextPref.setKey("edittext_preference");
editTextPref.setTitle(R.string.title_edittext_preference);
editTextPref.setSummary(R.string.summary_edittext_preference);
dialogBasedPrefCat.addPreference(editTextPref);

// List preference
ListPreference listPref = new ListPreference(this);
listPref.setEntries(R.array.entries_list_preference);
listPref.setEntryValues(R.array.entryvalues_list_preference);
listPref.setDialogTitle(R.string.dialog_title_list_preference);
listPref.setKey("list_preference");
listPref.setTitle(R.string.title_list_preference);
listPref.setSummary(R.string.summary_list_preference);
dialogBasedPrefCat.addPreference(listPref);

// Launch preferences
PreferenceCategory launchPrefCat = new PreferenceCategory(this);
launchPrefCat.setTitle(R.string.launch_preferences);
root.addPreference(launchPrefCat);

/*
* The Preferences screenPref serves as a screen break (similar to page
* break in word processing). Like for other preference types, we assign
* a key here so that it is able to save and restore its instance state.
*/
// Screen preference
PreferenceScreen screenPref = getPreferenceManager().createPreferenceScreen(this);
screenPref.setKey("screen_preference");
screenPref.setTitle(R.string.title_screen_preference);
screenPref.setSummary(R.string.summary_screen_preference);
launchPrefCat.addPreference(screenPref);

/*
* You can add more preferences to screenPref that will be shown on the
* next screen.childCheckBoxPref.setDependency(PARENT_CHECKBOX_PREFERENCE);
*/

// Example of next screen toggle preference
CheckBoxPreference nextScreenCheckBoxPref = new CheckBoxPreference(this);
nextScreenCheckBoxPref.setKey("next_screen_toggle_preference");
nextScreenCheckBoxPref.setTitle(R.string.title_next_screen_toggle_preference);
nextScreenCheckBoxPref.setSummary(R.string.summary_next_screen_toggle_preference);
screenPref.addPreference(nextScreenCheckBoxPref);

// Intent preference
PreferenceScreen intentPref = getPreferenceManager().createPreferenceScreen(this);
intentPref.setIntent(new Intent().setAction(Intent.ACTION_VIEW)
.setData(Uri.parse("http://www.android.com")));
intentPref.setTitle(R.string.title_intent_preference);
intentPref.setSummary(R.string.summary_intent_preference);
launchPrefCat.addPreference(intentPref);

// Preference attributes
PreferenceCategory prefAttrsCat = new PreferenceCategory(this);
prefAttrsCat.setTitle(R.string.preference_attributes);
root.addPreference(prefAttrsCat);

// Visual parent toggle preference
CheckBoxPreference parentCheckBoxPref = new CheckBoxPreference(this);
parentCheckBoxPref.setTitle(R.string.title_parent_preference);
parentCheckBoxPref.setSummary(R.string.summary_parent_preference);
prefAttrsCat.addPreference(parentCheckBoxPref);
parentCheckBoxPref.setKey(PARENT_CHECKBOX_PREFERENCE);

// Visual child toggle preference
// See res/values/attrs.xml for the <declare-styleable> that defines
// TogglePrefAttrs.
TypedArray a = obtainStyledAttributes(R.styleable.TogglePrefAttrs);
CheckBoxPreference childCheckBoxPref = new CheckBoxPreference(this);
childCheckBoxPref.setTitle(R.string.title_child_preference);
childCheckBoxPref.setSummary(R.string.summary_child_preference);
childCheckBoxPref.setLayoutResource(
a.getResourceId(R.styleable.TogglePrefAttrs_android_preferenceLayoutChild,
0));
prefAttrsCat.addPreference(childCheckBoxPref);
childCheckBoxPref.setDependency(PARENT_CHECKBOX_PREFERENCE);
a.recycle();
}

基本上和使用XML定义一一对应。