public
abstract
class
PreferenceFragmentCompat
extends Fragment
implements
PreferenceManager.OnPreferenceTreeClickListener,
PreferenceManager.OnDisplayPreferenceDialogListener,
PreferenceManager.OnNavigateToScreenListener,
DialogPreference.TargetFragment
java.lang.Object | ||
↳ | android.support.v4.app.Fragment | |
↳ | android.support.v7.preference.PreferenceFragmentCompat |
Shows a hierarchy of Preference
objects as
lists. These preferences will
automatically save to SharedPreferences
as the user interacts with
them. To retrieve an instance of SharedPreferences
that the
preference hierarchy in this fragment will use, call
getDefaultSharedPreferences(android.content.Context)
with a context in the same package as this fragment.
Furthermore, the preferences shown will follow the visual style of system preferences. It is easy to create a hierarchy of preferences (that can be shown on multiple screens) via XML. For these reasons, it is recommended to use this fragment (as a superclass) to deal with preferences in applications.
A PreferenceScreen
object should be at the top of the preference
hierarchy. Furthermore, subsequent PreferenceScreen
in the hierarchy
denote a screen break--that is the preferences contained within subsequent
PreferenceScreen
should be shown on another screen. The preference
framework handles this by calling onNavigateToScreen(PreferenceScreen)
.
The preference hierarchy can be formed in multiple ways:
Activities
that each specify its own
preferences in an XML file via Activity
meta-data
PreferenceScreen
To inflate from XML, use the addPreferencesFromResource(int)
. The
root element should be a PreferenceScreen
. Subsequent elements can point
to actual Preference
subclasses. As mentioned above, subsequent
PreferenceScreen
in the hierarchy will result in the screen break.
To specify an object hierarchy rooted with PreferenceScreen
, use
setPreferenceScreen(PreferenceScreen)
.
As a convenience, this fragment implements a click listener for any
preference in the current hierarchy, see
onPreferenceTreeClick(Preference)
.
For information about using PreferenceFragment
,
read the Settings
guide.
The following sample code shows a simple preference fragment that is populated from a resource. The resource it loads is:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <PreferenceCategory android:title="@string/inline_preferences"> <CheckBoxPreference android:key="checkbox_preference" android:title="@string/title_checkbox_preference" android:summary="@string/summary_checkbox_preference" /> </PreferenceCategory> <PreferenceCategory android:title="@string/dialog_based_preferences"> <EditTextPreference android:key="edittext_preference" android:title="@string/title_edittext_preference" android:summary="@string/summary_edittext_preference" android:dialogTitle="@string/dialog_title_edittext_preference" /> <ListPreference android:key="list_preference" android:title="@string/title_list_preference" android:summary="@string/summary_list_preference" android:entries="@array/entries_list_preference" android:entryValues="@array/entryvalues_list_preference" android:dialogTitle="@string/dialog_title_list_preference" /> </PreferenceCategory> <PreferenceCategory android:title="@string/launch_preferences"> <!-- This PreferenceScreen tag serves as a screen break (similar to page break in word processing). Like for other preference types, we assign a key here so it is able to save and restore its instance state. --> <PreferenceScreen android:key="screen_preference" android:title="@string/title_screen_preference" android:summary="@string/summary_screen_preference"> <!-- You can place more preferences here that will be shown on the next screen. --> <CheckBoxPreference android:key="next_screen_checkbox_preference" android:title="@string/title_next_screen_toggle_preference" android:summary="@string/summary_next_screen_toggle_preference" /> </PreferenceScreen> <PreferenceScreen android:title="@string/title_intent_preference" android:summary="@string/summary_intent_preference"> <intent android:action="android.intent.action.VIEW" android:data="http://www.android.com" /> </PreferenceScreen> </PreferenceCategory> <PreferenceCategory android:title="@string/preference_attributes"> <CheckBoxPreference android:key="parent_checkbox_preference" android:title="@string/title_parent_preference" android:summary="@string/summary_parent_preference" /> <!-- The visual style of a child is defined by this styled theme attribute. --> <CheckBoxPreference android:key="child_checkbox_preference" android:dependency="parent_checkbox_preference" android:layout="?android:attr/preferenceLayoutChild" android:title="@string/title_child_preference" android:summary="@string/summary_child_preference" /> </PreferenceCategory> </PreferenceScreen>
The fragment implementation itself simply populates the preferences when created. Note that the preferences framework takes care of loading the current values out of the app preferences and writing them when changed:
public static class PrefsFragment extends PreferenceFragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Load the preferences from an XML resource addPreferencesFromResource(R.xml.preferences); } }
See also:
Nested classes | |
---|---|
interface |
PreferenceFragmentCompat.OnPreferenceDisplayDialogCallback
|
interface |
PreferenceFragmentCompat.OnPreferenceStartFragmentCallback
Interface that PreferenceFragment's containing activity should implement to be able to process preference items that wish to switch to a specified fragment. |
interface |
PreferenceFragmentCompat.OnPreferenceStartScreenCallback
Interface that PreferenceFragment's containing activity should implement to be able to process preference items that wish to switch to a new screen of preferences. |
XML attributes | |
---|---|
android:divider |
List separator to draw between preference views
May be a reference to another resource, in the form
" |
android:dividerHeight |
List separator height
May be a dimension value, which is a floating point number appended with a
unit such as " |
Constants | |
---|---|
String |
ARG_PREFERENCE_ROOT
Fragment argument used to specify the tag of the desired root
|
Public constructors | |
---|---|
PreferenceFragmentCompat()
|
Public methods | |
---|---|
void
|
addPreferencesFromResource(int preferencesResId)
Inflates the given XML resource and adds the preference hierarchy to the current preference hierarchy. |
Preference
|
findPreference(CharSequence key)
Finds a |
final
RecyclerView
|
getListView()
|
PreferenceManager
|
getPreferenceManager()
Returns the |
PreferenceScreen
|
getPreferenceScreen()
Gets the root of the preference hierarchy that this fragment is showing. |
void
|
onActivityCreated(Bundle savedInstanceState)
Called when the fragment's activity has been created and this fragment's view hierarchy instantiated. |
void
|
onCreate(Bundle savedInstanceState)
Called to do initial creation of a fragment. |
RecyclerView.LayoutManager
|
onCreateLayoutManager()
Called from |
abstract
void
|
onCreatePreferences(Bundle savedInstanceState, String rootKey)
Called during |
RecyclerView
|
onCreateRecyclerView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState)
Creates the |
View
|
onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
Called to have the fragment instantiate its user interface view. |
void
|
onDestroyView()
Called when the view previously created by |
void
|
onDisplayPreferenceDialog(Preference preference)
Called when a preference in the tree requests to display a dialog. |
void
|
onNavigateToScreen(PreferenceScreen preferenceScreen)
Called by
|
boolean
|
onPreferenceTreeClick(Preference preference)
Called when a preference in the tree rooted at this
|
void
|
onSaveInstanceState(Bundle outState)
Called to ask the fragment to save its current dynamic state, so it can later be reconstructed in a new instance of its process is restarted. |
void
|
onStart()
Called when the Fragment is visible to the user. |
void
|
onStop()
Called when the Fragment is no longer started. |
void
|
onViewCreated(View view, Bundle savedInstanceState)
Called immediately after |
void
|
scrollToPreference(Preference preference)
|
void
|
scrollToPreference(String key)
|
void
|
setDivider(Drawable divider)
Sets the drawable that will be drawn between each item in the list. |
void
|
setDividerHeight(int height)
Sets the height of the divider that will be drawn between each item in the list. |
void
|
setPreferenceScreen(PreferenceScreen preferenceScreen)
Sets the root of the preference hierarchy that this fragment is showing. |
void
|
setPreferencesFromResource(int preferencesResId, String key)
Inflates the given XML resource and replaces the current preference hierarchy (if any) with
the preference hierarchy rooted at |
Protected methods | |
---|---|
Adapter
|
onCreateAdapter(PreferenceScreen preferenceScreen)
Creates the root adapter. |
Inherited methods | |
---|---|
From
class
android.support.v4.app.Fragment
| |
From
class
java.lang.Object
| |
From
interface
android.content.ComponentCallbacks
| |
From
interface
android.view.View.OnCreateContextMenuListener
| |
From
interface
android.support.v7.preference.PreferenceManager.OnPreferenceTreeClickListener
| |
From
interface
android.support.v7.preference.PreferenceManager.OnDisplayPreferenceDialogListener
| |
From
interface
android.support.v7.preference.PreferenceManager.OnNavigateToScreenListener
| |
From
interface
android.support.v7.preference.DialogPreference.TargetFragment
|
List separator to draw between preference views
May be a reference to another resource, in the form
"@[+][package:]type/name
" or a theme
attribute in the form
"?[package:]type/name
".
May be a color value, in the form of "#rgb
",
"#argb
", "#rrggbb
#aarrggbb".
Related methods:
List separator height
May be a dimension value, which is a floating point number appended with a
unit such as "14.5sp
".
Available units are: px (pixels), dp (density-independent pixels),
sp (scaled pixels based on preferred font size), in (inches), and
mm (millimeters).
Related methods:
String ARG_PREFERENCE_ROOT
Fragment argument used to specify the tag of the desired root
PreferenceScreen
object.
Constant Value: "android.support.v7.preference.PreferenceFragmentCompat.PREFERENCE_ROOT"
PreferenceFragmentCompat ()
void addPreferencesFromResource (int preferencesResId)
Inflates the given XML resource and adds the preference hierarchy to the current preference hierarchy.
Parameters | |
---|---|
preferencesResId |
int :
The XML resource ID to inflate.
|
Preference findPreference (CharSequence key)
Finds a Preference
based on its key.
Parameters | |
---|---|
key |
CharSequence :
The key of the preference to retrieve. |
Returns | |
---|---|
Preference |
The Preference with the key, or null. |
See also:
PreferenceManager getPreferenceManager ()
Returns the PreferenceManager
used by this fragment.
Returns | |
---|---|
PreferenceManager |
The PreferenceManager .
|
PreferenceScreen getPreferenceScreen ()
Gets the root of the preference hierarchy that this fragment is showing.
Returns | |
---|---|
PreferenceScreen |
The PreferenceScreen that is the root of the preference
hierarchy.
|
void onActivityCreated (Bundle savedInstanceState)
Called when the fragment's activity has been created and this
fragment's view hierarchy instantiated. It can be used to do final
initialization once these pieces are in place, such as retrieving
views or restoring state. It is also useful for fragments that use
setRetainInstance(boolean)
to retain their instance,
as this callback tells the fragment when it is fully associated with
the new activity instance. This is called after onCreateView(LayoutInflater, ViewGroup, Bundle)
and before onViewStateRestored(Bundle)
.
Parameters | |
---|---|
savedInstanceState |
Bundle :
If the fragment is being re-created from
a previous saved state, this is the state.
|
void onCreate (Bundle savedInstanceState)
Called to do initial creation of a fragment. This is called after
onAttach(Activity)
and before
onCreateView(LayoutInflater, ViewGroup, Bundle)
.
Note that this can be called while the fragment's activity is
still in the process of being created. As such, you can not rely
on things like the activity's content view hierarchy being initialized
at this point. If you want to do work once the activity itself is
created, see onActivityCreated(Bundle)
.
Any restored child fragments will be created before the base
Fragment.onCreate
method returns.
Parameters | |
---|---|
savedInstanceState |
Bundle :
If the fragment is being re-created from
a previous saved state, this is the state.
|
RecyclerView.LayoutManager onCreateLayoutManager ()
Called from onCreateRecyclerView(LayoutInflater, ViewGroup, Bundle)
to create the
RecyclerView.LayoutManager
for the created
RecyclerView
.
Returns | |
---|---|
RecyclerView.LayoutManager |
A new RecyclerView.LayoutManager instance.
|
void onCreatePreferences (Bundle savedInstanceState, String rootKey)
Called during onCreate(Bundle)
to supply the preferences for this fragment.
Subclasses are expected to call setPreferenceScreen(PreferenceScreen)
either
directly or via helper methods such as addPreferencesFromResource(int)
.
Parameters | |
---|---|
savedInstanceState |
Bundle :
If the fragment is being re-created from
a previous saved state, this is the state. |
rootKey |
String :
If non-null, this preference fragment should be rooted at the
PreferenceScreen with this key.
|
RecyclerView onCreateRecyclerView (LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState)
Creates the RecyclerView
used to display the preferences.
Subclasses may override this to return a customized
RecyclerView
.
Parameters | |
---|---|
inflater |
LayoutInflater :
The LayoutInflater object that can be used to inflate the
RecyclerView . |
parent |
ViewGroup :
The parent View that the RecyclerView will be attached to.
This method should not add the view itself, but this can be used to generate
the LayoutParams of the view. |
savedInstanceState |
Bundle :
If non-null, this view is being re-constructed from a previous
saved state as given here |
Returns | |
---|---|
RecyclerView |
A new RecyclerView object to be placed into the view hierarchy |
View onCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
Called to have the fragment instantiate its user interface view.
This is optional, and non-graphical fragments can return null (which
is the default implementation). This will be called between
onCreate(Bundle)
and onActivityCreated(Bundle)
.
If you return a View from here, you will later be called in
onDestroyView()
when the view is being released.
Parameters | |
---|---|
inflater |
LayoutInflater :
The LayoutInflater object that can be used to inflate
any views in the fragment, |
container |
ViewGroup :
If non-null, this is the parent view that the fragment's
UI should be attached to. The fragment should not add the view itself,
but this can be used to generate the LayoutParams of the view. |
savedInstanceState |
Bundle :
If non-null, this fragment is being re-constructed
from a previous saved state as given here. |
Returns | |
---|---|
View |
Return the View for the fragment's UI, or null. |
void onDestroyView ()
Called when the view previously created by onCreateView(LayoutInflater, ViewGroup, Bundle)
has
been detached from the fragment. The next time the fragment needs
to be displayed, a new view will be created. This is called
after onStop()
and before onDestroy()
. It is called
regardless of whether onCreateView(LayoutInflater, ViewGroup, Bundle)
returned a
non-null view. Internally it is called after the view's state has
been saved but before it has been removed from its parent.
void onDisplayPreferenceDialog (Preference preference)
Called when a preference in the tree requests to display a dialog. Subclasses should override this method to display custom dialogs or to handle dialogs for custom preference classes.
Parameters | |
---|---|
preference |
Preference :
The Preference object requesting the dialog.
|
void onNavigateToScreen (PreferenceScreen preferenceScreen)
Called by
onClick()
in order to navigate to a
new screen of preferences. Calls
onPreferenceStartScreen(PreferenceFragmentCompat, PreferenceScreen)
if the target fragment or containing activity implements
PreferenceFragmentCompat.OnPreferenceStartScreenCallback
.
Parameters | |
---|---|
preferenceScreen |
PreferenceScreen :
The PreferenceScreen to
navigate to.
|
boolean onPreferenceTreeClick (Preference preference)
Called when a preference in the tree rooted at this
PreferenceScreen
has been clicked.
Parameters | |
---|---|
preference |
Preference :
The preference that was clicked. |
Returns | |
---|---|
boolean |
Whether the click was handled. |
void onSaveInstanceState (Bundle outState)
Called to ask the fragment to save its current dynamic state, so it
can later be reconstructed in a new instance of its process is
restarted. If a new instance of the fragment later needs to be
created, the data you place in the Bundle here will be available
in the Bundle given to onCreate(Bundle)
,
onCreateView(LayoutInflater, ViewGroup, Bundle)
, and
onActivityCreated(Bundle)
.
This corresponds to Activity.onSaveInstanceState(Bundle)
and most of the discussion there
applies here as well. Note however: this method may be called
at any time before onDestroy()
. There are many situations
where a fragment may be mostly torn down (such as when placed on the
back stack with no UI showing), but its state will not be saved until
its owning activity actually needs to save its state.
Parameters | |
---|---|
outState |
Bundle :
Bundle in which to place your saved state.
|
void onStart ()
Called when the Fragment is visible to the user. This is generally
tied to Activity.onStart
of the containing
Activity's lifecycle.
void onStop ()
Called when the Fragment is no longer started. This is generally
tied to Activity.onStop
of the containing
Activity's lifecycle.
void onViewCreated (View view, Bundle savedInstanceState)
Called immediately after onCreateView(LayoutInflater, ViewGroup, Bundle)
has returned, but before any saved state has been restored in to the view.
This gives subclasses a chance to initialize themselves once
they know their view hierarchy has been completely created. The fragment's
view hierarchy is not however attached to its parent at this point.
Parameters | |
---|---|
view |
View :
The View returned by onCreateView(LayoutInflater, ViewGroup, Bundle) . |
savedInstanceState |
Bundle :
If non-null, this fragment is being re-constructed
from a previous saved state as given here.
|
void setDivider (Drawable divider)
Sets the drawable that will be drawn between each item in the list.
Note: If the drawable does not have an intrinsic
height, you should also call setDividerHeight(int)
.
Related XML Attributes:
Parameters | |
---|---|
divider |
Drawable :
the drawable to use |
void setDividerHeight (int height)
Sets the height of the divider that will be drawn between each item in the list. Calling
this will override the intrinsic height as set by setDivider(Drawable)
Related XML Attributes:
Parameters | |
---|---|
height |
int :
The new height of the divider in pixels. |
void setPreferenceScreen (PreferenceScreen preferenceScreen)
Sets the root of the preference hierarchy that this fragment is showing.
Parameters | |
---|---|
preferenceScreen |
PreferenceScreen :
The root PreferenceScreen of the preference hierarchy.
|
void setPreferencesFromResource (int preferencesResId, String key)
Inflates the given XML resource and replaces the current preference hierarchy (if any) with
the preference hierarchy rooted at key
.
Parameters | |
---|---|
preferencesResId |
int :
The XML resource ID to inflate. |
key |
String :
The preference key of the PreferenceScreen
to use as the root of the preference hierarchy, or null to use the root
PreferenceScreen .
|
Adapter onCreateAdapter (PreferenceScreen preferenceScreen)
Creates the root adapter.
Parameters | |
---|---|
preferenceScreen |
PreferenceScreen :
Preference screen object to create the adapter for. |
Returns | |
---|---|
Adapter |
An adapter that contains the preferences contained in this PreferenceScreen .
|