Here's an example XML layout of a PreferenceScreen:
*
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android"
android:key="first_preferencescreen">
<CheckBoxPreference
android:key="wifi enabled"
android:title="WiFi" />
<PreferenceScreen
android:key="second_preferencescreen"
android:title="WiFi settings">
<CheckBoxPreference
android:key="prefer wifi"
android:title="Prefer WiFi" />
... other preferences here ...
</PreferenceScreen>
</PreferenceScreen>
* * In this example, the "first_preferencescreen" will be used as the root of the * hierarchy and given to a {@link PreferenceActivity}. The first screen will * show preferences "WiFi" (which can be used to quickly enable/disable WiFi) * and "WiFi settings". The "WiFi settings" is the "second_preferencescreen" and when * clicked will show another screen of preferences such as "Prefer WiFi" (and * the other preferences that are children of the "second_preferencescreen" tag). * *
For information about building a settings UI with Preferences, * read the Settings * guide.
** This {@link PreferenceScreen} will NOT appear in the returned adapter, instead * it appears in the hierarchy above this {@link PreferenceScreen}. *
* This adapter's {@link Adapter#getItem(int)} should always return a
* subclass of {@link Preference}.
*
* @return An adapter that provides the {@link Preference} contained in this
* {@link PreferenceScreen}.
*/
public ListAdapter getRootAdapter() {
if (mRootAdapter == null) {
mRootAdapter = onCreateRootAdapter();
}
return mRootAdapter;
}
/**
* Creates the root adapter.
*
* @return An adapter that contains the preferences contained in this {@link PreferenceScreen}.
* @see #getRootAdapter()
*/
protected ListAdapter onCreateRootAdapter() {
return new PreferenceGroupAdapter(this);
}
/**
* Binds a {@link ListView} to the preferences contained in this {@link PreferenceScreen} via
* {@link #getRootAdapter()}. It also handles passing list item clicks to the corresponding
* {@link Preference} contained by this {@link PreferenceScreen}.
*
* @param listView The list view to attach to.
*/
public void bind(ListView listView) {
listView.setOnItemClickListener(this);
listView.setAdapter(getRootAdapter());
onAttachedToActivity();
}
@Override
protected void onClick() {
if (getIntent() != null || getFragment() != null || getPreferenceCount() == 0) {
return;
}
showDialog(null);
}
private void showDialog(Bundle state) {
Context context = getContext();
if (mListView != null) {
mListView.setAdapter(null);
}
LayoutInflater inflater = (LayoutInflater)
context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View childPrefScreen = inflater.inflate(
com.android.internal.R.layout.preference_list_fragment, null);
mListView = (ListView) childPrefScreen.findViewById(android.R.id.list);
bind(mListView);
// Set the title bar if title is available, else no title bar
final CharSequence title = getTitle();
Dialog dialog = mDialog = new Dialog(context, context.getThemeResId());
if (TextUtils.isEmpty(title)) {
dialog.getWindow().requestFeature(Window.FEATURE_NO_TITLE);
} else {
dialog.setTitle(title);
}
dialog.setContentView(childPrefScreen);
dialog.setOnDismissListener(this);
if (state != null) {
dialog.onRestoreInstanceState(state);
}
// Add the screen to the list of preferences screens opened as dialogs
getPreferenceManager().addPreferencesScreen(dialog);
dialog.show();
}
public void onDismiss(DialogInterface dialog) {
mDialog = null;
getPreferenceManager().removePreferencesScreen(dialog);
}
/**
* Used to get a handle to the dialog.
* This is useful for cases where we want to manipulate the dialog
* as we would with any other activity or view.
*/
public Dialog getDialog() {
return mDialog;
}
public void onItemClick(AdapterView parent, View view, int position, long id) {
// If the list has headers, subtract them from the index.
if (parent instanceof ListView) {
position -= ((ListView) parent).getHeaderViewsCount();
}
Object item = getRootAdapter().getItem(position);
if (!(item instanceof Preference)) return;
final Preference preference = (Preference) item;
preference.performClick(this);
}
@Override
protected boolean isOnSameScreenAsChildren() {
return false;
}
@Override
protected Parcelable onSaveInstanceState() {
final Parcelable superState = super.onSaveInstanceState();
final Dialog dialog = mDialog;
if (dialog == null || !dialog.isShowing()) {
return superState;
}
final SavedState myState = new SavedState(superState);
myState.isDialogShowing = true;
myState.dialogBundle = dialog.onSaveInstanceState();
return myState;
}
@Override
protected void onRestoreInstanceState(Parcelable state) {
if (state == null || !state.getClass().equals(SavedState.class)) {
// Didn't save state for us in onSaveInstanceState
super.onRestoreInstanceState(state);
return;
}
SavedState myState = (SavedState) state;
super.onRestoreInstanceState(myState.getSuperState());
if (myState.isDialogShowing) {
showDialog(myState.dialogBundle);
}
}
private static class SavedState extends BaseSavedState {
boolean isDialogShowing;
Bundle dialogBundle;
public SavedState(Parcel source) {
super(source);
isDialogShowing = source.readInt() == 1;
dialogBundle = source.readBundle();
}
@Override
public void writeToParcel(Parcel dest, int flags) {
super.writeToParcel(dest, flags);
dest.writeInt(isDialogShowing ? 1 : 0);
dest.writeBundle(dialogBundle);
}
public SavedState(Parcelable superState) {
super(superState);
}
public static final Parcelable.Creator