Methods
public static LeanbackListPreferenceDialogFragmentCompat	newInstanceMulti(java.lang.String key) Create a new LeanbackListPreferenceDialogFragmentCompat.
public static LeanbackListPreferenceDialogFragmentCompat	newInstanceSingle(java.lang.String key) Create a new LeanbackListPreferenceDialogFragmentCompat.
public void	onCreate(Bundle savedInstanceState) Called to do initial creation of a fragment.
public View	onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) Called to have the fragment instantiate its user interface view.
public 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 if its process is restarted.
from LeanbackPreferenceDialogFragmentCompat	getPreference
from Fragment	dump, equals, getActivity, getAllowEnterTransitionOverlap, getAllowReturnTransitionOverlap, getArguments, getChildFragmentManager, getContext, getDefaultViewModelCreationExtras, getDefaultViewModelProviderFactory, getEnterTransition, getExitTransition, getFragmentManager, getHost, getId, getLayoutInflater, getLayoutInflater, getLifecycle, getLoaderManager, getParentFragment, getParentFragmentManager, getReenterTransition, getResources, getRetainInstance, getReturnTransition, getSavedStateRegistry, getSharedElementEnterTransition, getSharedElementReturnTransition, getString, getString, getTag, getTargetFragment, getTargetRequestCode, getText, getUserVisibleHint, getView, getViewLifecycleOwner, getViewLifecycleOwnerLiveData, getViewModelStore, hashCode, hasOptionsMenu, instantiate, instantiate, isAdded, isDetached, isHidden, isInLayout, isMenuVisible, isRemoving, isResumed, isStateSaved, isVisible, onActivityCreated, onActivityResult, onAttach, onAttach, onAttachFragment, onConfigurationChanged, onContextItemSelected, onCreateAnimation, onCreateAnimator, onCreateContextMenu, onCreateOptionsMenu, onDestroy, onDestroyOptionsMenu, onDestroyView, onDetach, onGetLayoutInflater, onHiddenChanged, onInflate, onInflate, onLowMemory, onMultiWindowModeChanged, onOptionsItemSelected, onOptionsMenuClosed, onPause, onPictureInPictureModeChanged, onPrepareOptionsMenu, onPrimaryNavigationFragmentChanged, onRequestPermissionsResult, onResume, onStart, onStop, onViewCreated, onViewStateRestored, postponeEnterTransition, postponeEnterTransition, registerForActivityResult, registerForActivityResult, registerForContextMenu, requestPermissions, requireActivity, requireArguments, requireContext, requireFragmentManager, requireHost, requireParentFragment, requireView, setAllowEnterTransitionOverlap, setAllowReturnTransitionOverlap, setArguments, setEnterSharedElementCallback, setEnterTransition, setExitSharedElementCallback, setExitTransition, setHasOptionsMenu, setInitialSavedState, setMenuVisibility, setReenterTransition, setRetainInstance, setReturnTransition, setSharedElementEnterTransition, setSharedElementReturnTransition, setTargetFragment, setUserVisibleHint, shouldShowRequestPermissionRationale, startActivity, startActivity, startActivityForResult, startActivityForResult, startIntentSenderForResult, startPostponedEnterTransition, toString, unregisterForContextMenu
from java.lang.Object	clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructors

public LeanbackListPreferenceDialogFragmentCompat()

Methods

public static LeanbackListPreferenceDialogFragmentCompat newInstanceSingle(java.lang.String key)

Create a new LeanbackListPreferenceDialogFragmentCompat.

Parameters:

key: The key of ListPreference it will be created from.

Returns:

A new LeanbackListPreferenceDialogFragmentCompat to display.

public static LeanbackListPreferenceDialogFragmentCompat newInstanceMulti(java.lang.String key)

Create a new LeanbackListPreferenceDialogFragmentCompat.

Parameters:

key: The key of MultiSelectListPreference it will be created from.

Returns:

A new LeanbackListPreferenceDialogFragmentCompat to display.

public void onCreate(Bundle savedInstanceState)

Called to do initial creation of a fragment. This is called after Fragment.onAttach(Activity) and before Fragment.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, add a LifecycleObserver on the activity's Lifecycle, removing it when it receives the callback.

Any restored child fragments will be created before the base Fragment.onCreate method returns.

Parameters:

savedInstanceState: If the fragment is being re-created from a previous saved state, this is the state.

public 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 if 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 Fragment.onCreate(Bundle), Fragment.onCreateView(LayoutInflater, ViewGroup, Bundle), and Fragment.onViewCreated(View, Bundle).

This corresponds to and most of the discussion there applies here as well. Note however: this method may be called at any time before Fragment.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 in which to place your saved state.

public 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. This will be called between Fragment.onCreate(Bundle) and Fragment.onViewCreated(View, Bundle).

A default View can be returned by calling Fragment.Fragment(int) in your constructor. Otherwise, this method returns null.

It is recommended to only inflate the layout in this method and move logic that operates on the returned View to Fragment.onViewCreated(View, Bundle).

If you return a View from here, you will later be called in Fragment.onDestroyView() when the view is being released.

Parameters:

inflater: The LayoutInflater object that can be used to inflate any views in the fragment,
container: 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: If non-null, this fragment is being re-constructed from a previous saved state as given here.

Returns:

Return the View for the fragment's UI, or null.

Source

/*
 * Copyright 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.leanback.preference;

import android.content.Context;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.TypedValue;
import android.view.ContextThemeWrapper;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Checkable;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.collection.ArraySet;
import androidx.leanback.widget.VerticalGridView;
import androidx.preference.DialogPreference;
import androidx.preference.ListPreference;
import androidx.preference.MultiSelectListPreference;
import androidx.recyclerview.widget.RecyclerView;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * Implemented a dialog to show {@link ListPreference} or {@link MultiSelectListPreference}.
 */
public class LeanbackListPreferenceDialogFragmentCompat extends
        LeanbackPreferenceDialogFragmentCompat {

    private static final String SAVE_STATE_IS_MULTI =
            "LeanbackListPreferenceDialogFragment.isMulti";
    private static final String SAVE_STATE_ENTRIES = "LeanbackListPreferenceDialogFragment.entries";
    private static final String SAVE_STATE_ENTRY_VALUES =
            "LeanbackListPreferenceDialogFragment.entryValues";
    private static final String SAVE_STATE_TITLE = "LeanbackListPreferenceDialogFragment.title";
    private static final String SAVE_STATE_MESSAGE = "LeanbackListPreferenceDialogFragment.message";
    private static final String SAVE_STATE_INITIAL_SELECTIONS =
            "LeanbackListPreferenceDialogFragment.initialSelections";
    private static final String SAVE_STATE_INITIAL_SELECTION =
            "LeanbackListPreferenceDialogFragment.initialSelection";

    private boolean mMulti;
    private CharSequence[] mEntries;
    private CharSequence[] mEntryValues;
    private CharSequence mDialogTitle;
    private CharSequence mDialogMessage;
    Set<String> mInitialSelections;
    private String mInitialSelection;

    /**
     * Create a new LeanbackListPreferenceDialogFragmentCompat.
     * @param key The key of {@link ListPreference} it will be created from.
     * @return A new LeanbackListPreferenceDialogFragmentCompat to display.
     */
    public static LeanbackListPreferenceDialogFragmentCompat newInstanceSingle(String key) {
        final Bundle args = new Bundle(1);
        args.putString(ARG_KEY, key);

        final LeanbackListPreferenceDialogFragmentCompat
                fragment = new LeanbackListPreferenceDialogFragmentCompat();
        fragment.setArguments(args);

        return fragment;
    }

    /**
     * Create a new LeanbackListPreferenceDialogFragmentCompat.
     * @param key The key of {@link MultiSelectListPreference} it will be created from.
     * @return A new LeanbackListPreferenceDialogFragmentCompat to display.
     */
    public static LeanbackListPreferenceDialogFragmentCompat newInstanceMulti(String key) {
        final Bundle args = new Bundle(1);
        args.putString(ARG_KEY, key);

        final LeanbackListPreferenceDialogFragmentCompat
                fragment = new LeanbackListPreferenceDialogFragmentCompat();
        fragment.setArguments(args);

        return fragment;
    }

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

        if (savedInstanceState == null) {
            final DialogPreference preference = getPreference();
            mDialogTitle = preference.getDialogTitle();
            mDialogMessage = preference.getDialogMessage();

            if (preference instanceof ListPreference) {
                mMulti = false;
                mEntries = ((ListPreference) preference).getEntries();
                mEntryValues = ((ListPreference) preference).getEntryValues();
                mInitialSelection = ((ListPreference) preference).getValue();
            } else if (preference instanceof MultiSelectListPreference) {
                mMulti = true;
                mEntries = ((MultiSelectListPreference) preference).getEntries();
                mEntryValues = ((MultiSelectListPreference) preference).getEntryValues();
                mInitialSelections = ((MultiSelectListPreference) preference).getValues();
            } else {
                throw new IllegalArgumentException("Preference must be a ListPreference or "
                        + "MultiSelectListPreference");
            }
        } else {
            mDialogTitle = savedInstanceState.getCharSequence(SAVE_STATE_TITLE);
            mDialogMessage = savedInstanceState.getCharSequence(SAVE_STATE_MESSAGE);
            mMulti = savedInstanceState.getBoolean(SAVE_STATE_IS_MULTI);
            mEntries = savedInstanceState.getCharSequenceArray(SAVE_STATE_ENTRIES);
            mEntryValues = savedInstanceState.getCharSequenceArray(SAVE_STATE_ENTRY_VALUES);
            if (mMulti) {
                final String[] initialSelections = savedInstanceState.getStringArray(
                        SAVE_STATE_INITIAL_SELECTIONS);
                mInitialSelections = new ArraySet<>(
                        initialSelections != null ? initialSelections.length : 0);
                if (initialSelections != null) {
                    Collections.addAll(mInitialSelections, initialSelections);
                }
            } else {
                mInitialSelection = savedInstanceState.getString(SAVE_STATE_INITIAL_SELECTION);
            }
        }
    }

    @Override
    public void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putCharSequence(SAVE_STATE_TITLE, mDialogTitle);
        outState.putCharSequence(SAVE_STATE_MESSAGE, mDialogMessage);
        outState.putBoolean(SAVE_STATE_IS_MULTI, mMulti);
        outState.putCharSequenceArray(SAVE_STATE_ENTRIES, mEntries);
        outState.putCharSequenceArray(SAVE_STATE_ENTRY_VALUES, mEntryValues);
        if (mMulti) {
            outState.putStringArray(SAVE_STATE_INITIAL_SELECTIONS,
                    mInitialSelections.toArray(new String[mInitialSelections.size()]));
        } else {
            outState.putString(SAVE_STATE_INITIAL_SELECTION, mInitialSelection);
        }
    }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        final TypedValue tv = new TypedValue();
        getActivity().getTheme().resolveAttribute(
                androidx.preference.R.attr.preferenceTheme, tv, true);
        int theme = tv.resourceId;
        if (theme == 0) {
            // Fallback to default theme.
            theme = R.style.PreferenceThemeOverlayLeanback;
        }
        Context styledContext = new ContextThemeWrapper(getActivity(), theme);
        LayoutInflater styledInflater = inflater.cloneInContext(styledContext);
        final View view = styledInflater.inflate(R.layout.leanback_list_preference_fragment,
                container, false);
        final VerticalGridView verticalGridView =
                (VerticalGridView) view.findViewById(android.R.id.list);

        verticalGridView.setWindowAlignment(VerticalGridView.WINDOW_ALIGN_BOTH_EDGE);
        verticalGridView.setFocusScrollStrategy(VerticalGridView.FOCUS_SCROLL_ALIGNED);
        verticalGridView.setAdapter(onCreateAdapter());
        verticalGridView.requestFocus();

        final CharSequence title = mDialogTitle;
        if (!TextUtils.isEmpty(title)) {
            final TextView titleView = (TextView) view.findViewById(R.id.decor_title);
            titleView.setText(title);
        }

        final CharSequence message = mDialogMessage;
        if (!TextUtils.isEmpty(message)) {
            final TextView messageView = (TextView) view.findViewById(android.R.id.message);
            messageView.setVisibility(View.VISIBLE);
            messageView.setText(message);
        }

        return view;
    }

    RecyclerView.Adapter onCreateAdapter() {
        //final DialogPreference preference = getPreference();
        if (mMulti) {
            return new AdapterMulti(mEntries, mEntryValues, mInitialSelections);
        } else {
            return new AdapterSingle(mEntries, mEntryValues, mInitialSelection);
        }
    }

    final class AdapterSingle extends RecyclerView.Adapter<ViewHolder>
            implements OnItemClickListener {

        private final CharSequence[] mEntries;
        private final CharSequence[] mEntryValues;
        private CharSequence mSelectedValue;

        AdapterSingle(CharSequence[] entries, CharSequence[] entryValues,
                CharSequence selectedValue) {
            mEntries = entries;
            mEntryValues = entryValues;
            mSelectedValue = selectedValue;
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
            final View view = inflater.inflate(R.layout.leanback_list_preference_item_single,
                    parent, false);
            return new ViewHolder(view, this);
        }

        @Override
        public void onBindViewHolder(ViewHolder holder, int position) {
            holder.getWidgetView().setChecked(
                    TextUtils.equals(mEntryValues[position].toString(), mSelectedValue));
            holder.getTitleView().setText(mEntries[position]);
        }

        @Override
        public int getItemCount() {
            return mEntries.length;
        }

        @Override
        public void onItemClick(ViewHolder viewHolder) {
            final int index = viewHolder.getAbsoluteAdapterPosition();
            if (index == RecyclerView.NO_POSITION) {
                return;
            }
            final CharSequence entry = mEntryValues[index];
            final ListPreference preference = (ListPreference) getPreference();
            if (index >= 0) {
                String value = mEntryValues[index].toString();
                if (preference.callChangeListener(value)) {
                    preference.setValue(value);
                    mSelectedValue = entry;
                }
            }

            getFragmentManager().popBackStack();
            notifyDataSetChanged();
        }
    }

    final class AdapterMulti extends RecyclerView.Adapter<ViewHolder>
            implements OnItemClickListener {

        private final CharSequence[] mEntries;
        private final CharSequence[] mEntryValues;
        private final Set<String> mSelections;

        AdapterMulti(CharSequence[] entries, CharSequence[] entryValues,
                Set<String> initialSelections) {
            mEntries = entries;
            mEntryValues = entryValues;
            mSelections = new HashSet<>(initialSelections);
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
            final View view = inflater.inflate(R.layout.leanback_list_preference_item_multi, parent,
                    false);
            return new ViewHolder(view, this);
        }

        @Override
        public void onBindViewHolder(ViewHolder holder, int position) {
            holder.getWidgetView().setChecked(
                    mSelections.contains(mEntryValues[position].toString()));
            holder.getTitleView().setText(mEntries[position]);
        }

        @Override
        public int getItemCount() {
            return mEntries.length;
        }

        @Override
        public void onItemClick(ViewHolder viewHolder) {
            final int index = viewHolder.getAbsoluteAdapterPosition();
            if (index == RecyclerView.NO_POSITION) {
                return;
            }
            final String entry = mEntryValues[index].toString();
            if (mSelections.contains(entry)) {
                mSelections.remove(entry);
            } else {
                mSelections.add(entry);
            }
            final MultiSelectListPreference multiSelectListPreference =
                    (MultiSelectListPreference) getPreference();
            // Pass copies of the set to callChangeListener and setValues to avoid mutations
            if (multiSelectListPreference.callChangeListener(new HashSet<>(mSelections))) {
                multiSelectListPreference.setValues(new HashSet<>(mSelections));
                mInitialSelections = mSelections;
            } else {
                // Change refused, back it out
                if (mSelections.contains(entry)) {
                    mSelections.remove(entry);
                } else {
                    mSelections.add(entry);
                }
            }

            notifyDataSetChanged();
        }
    }

    private interface OnItemClickListener {
        void onItemClick(ViewHolder viewHolder);
    }

    /**
     * ViewHolder for each Item in the List.
     */
    public static final class ViewHolder extends RecyclerView.ViewHolder
            implements View.OnClickListener {

        private final Checkable mWidgetView;
        private final TextView mTitleView;
        private final ViewGroup mContainer;
        private final OnItemClickListener mListener;

        ViewHolder(@NonNull View view, @NonNull OnItemClickListener listener) {
            super(view);
            mWidgetView = (Checkable) view.findViewById(R.id.button);
            mContainer = (ViewGroup) view.findViewById(R.id.container);
            mTitleView = (TextView) view.findViewById(android.R.id.title);
            mContainer.setOnClickListener(this);
            mListener = listener;
        }

        public Checkable getWidgetView() {
            return mWidgetView;
        }

        public TextView getTitleView() {
            return mTitleView;
        }

        public ViewGroup getContainer() {
            return mContainer;
        }

        @Override
        public void onClick(View v) {
            mListener.onItemClick(this);
        }
    }
}