【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。