Show dialog to guide the user to input subtype enabler

    <!-- Title of the preference settings for custom input styles (language and keyboard layout pairs) [CHAR LIMIT=35]-->

    <string name="custom_input_styles_title">Custom input styles</string>

    <!-- Title of the option menu to add a new style entry in the preference settings [CHAR_LIMIT=16] -->

    <!-- Title of the option menu to add a new style entry in the preference settings [CHAR LIMIT=16] -->

    <string name="add_style">Add style</string>

    <!-- Title of the button to add custom style entry in the settings dialog [CHAR_LIMIT=12]  -->

    <!-- Title of the button to add custom style entry in the settings dialog [CHAR LIMIT=12] -->

    <string name="add">Add</string>

    <!-- Title of the button to remove a custom style entry in the settings dialog [CHAR_LIMIT=12]  -->

    <!-- Title of the button to remove a custom style entry in the settings dialog [CHAR LIMIT=12] -->

    <string name="remove">Remove</string>

    <!-- Title of the button to save a custom style entry in the settings dialog [CHAR_LIMIT=12]  -->

    <!-- Title of the button to save a custom style entry in the settings dialog [CHAR LIMIT=12] -->

    <string name="save">Save</string>

    <!-- Title of the spinner for choosing a language of custom style in the settings dialog [CHAR_LIMIT=12]  -->

    <!-- Title of the spinner for choosing a language of custom style in the settings dialog [CHAR LIMIT=12] -->

    <string name="subtype_locale">Language</string>

    <!-- Title of the spinner for choosing a keyboard layout of custom style in the settings dialog [CHAR_LIMIT=12]  -->

    <!-- Title of the spinner for choosing a keyboard layout of custom style in the settings dialog [CHAR LIMIT=12] -->

    <string name="keyboard_layout_set">Layout</string>

    <!-- The message of the dialog to note that a custom input style needs to be enabled. [CHAR LIMIT=64] -->

    <string name="custom_input_style_note_message">"Your custom input style needs to be enabled before you start using it. Do you want to enable it now?"</string>

    <!-- Title of the button to enable a custom input style entry in the settings dialog [CHAR LIMIT=12] -->

    <string name="enable">Enable</string>

    <!-- Title of the button to postpone enabling a custom input style entry in the settings dialog [CHAR LIMIT=12] -->

    <string name="not_now">Not now</string>

    <!-- Title of an option for usability study mode -->

    <string name="prefs_usability_study_mode">Usability study mode</string>

import android.app.Dialog;

import android.content.Context;

import android.content.DialogInterface;

import android.content.Intent;

import android.content.SharedPreferences;

import android.os.Bundle;

import android.os.Parcel;

import android.widget.Spinner;

import android.widget.SpinnerAdapter;

import com.android.inputmethod.compat.CompatUtils;

import java.util.TreeSet;

public class AdditionalSubtypeSettings extends PreferenceFragment {

    private KeyboardLayoutSetAdapter mKeyboardLayoutSetAdapter;

    private boolean mIsAddingNewSubtype;

    private AlertDialog mSubtypeEnablerNotificationDialog;

    private String mSubtypePreferenceKeyForSubtypeEnabler;

    private static final int MENU_ADD_SUBTYPE = Menu.FIRST;

    private static final String SAVE_IS_ADDING_NEW_SUBTYPE = "is_adding_new_subtype";

    private static final String KEY_IS_ADDING_NEW_SUBTYPE = "is_adding_new_subtype";

    private static final String KEY_IS_SUBTYPE_ENABLER_NOTIFICATION_DIALOG_OPEN =

            "is_subtype_enabler_notification_dialog_open";

    private static final String KEY_SUBTYPE_FOR_SUBTYPE_ENABLER = "subtype_for_subtype_enabler";

    static class SubtypeLocaleItem extends Pair<String, String>

            implements Comparable<SubtypeLocaleItem> {

        setPrefSubtypes(prefSubtypes, context);

        mIsAddingNewSubtype = (savedInstanceState != null)

                && savedInstanceState.containsKey(SAVE_IS_ADDING_NEW_SUBTYPE);

                && savedInstanceState.containsKey(KEY_IS_ADDING_NEW_SUBTYPE);

        if (mIsAddingNewSubtype) {

            getPreferenceScreen().addPreference(

                    SubtypePreference.newIncompleteSubtypePreference(context, mSubtypeProxy));

        }

        super.onActivityCreated(savedInstanceState);

        if (savedInstanceState != null && savedInstanceState.containsKey(

                KEY_IS_SUBTYPE_ENABLER_NOTIFICATION_DIALOG_OPEN)) {

            mSubtypePreferenceKeyForSubtypeEnabler = savedInstanceState.getString(

                    KEY_SUBTYPE_FOR_SUBTYPE_ENABLER);

            final SubtypePreference subtypePref = (SubtypePreference)findPreference(

                    mSubtypePreferenceKeyForSubtypeEnabler);

            mSubtypeEnablerNotificationDialog = createDialog(subtypePref);

            mSubtypeEnablerNotificationDialog.show();

        }

    }

    @Override

    public void onSaveInstanceState(Bundle outState) {

        super.onSaveInstanceState(outState);

        if (mIsAddingNewSubtype) {

            outState.putBoolean(SAVE_IS_ADDING_NEW_SUBTYPE, true);

            outState.putBoolean(KEY_IS_ADDING_NEW_SUBTYPE, true);

        }

        if (mSubtypeEnablerNotificationDialog != null

                && mSubtypeEnablerNotificationDialog.isShowing()) {

            outState.putBoolean(KEY_IS_SUBTYPE_ENABLER_NOTIFICATION_DIALOG_OPEN, true);

            outState.putString(

                    KEY_SUBTYPE_FOR_SUBTYPE_ENABLER, mSubtypePreferenceKeyForSubtypeEnabler);

        }

    }

        @Override

        public void onAddPressed(SubtypePreference subtypePref) {

            mIsAddingNewSubtype = false;

            setAdditionalInputMethodSubtypes(getPrefSubtypes());

            mSubtypePreferenceKeyForSubtypeEnabler = subtypePref.getKey();

            mSubtypeEnablerNotificationDialog = createDialog(subtypePref);

            mSubtypeEnablerNotificationDialog.show();

        }

        @Override

        }

    };

    private AlertDialog createDialog(SubtypePreference subtypePref) {

        final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());

        builder.setTitle(R.string.custom_input_styles_title)

                .setMessage(R.string.custom_input_style_note_message)

                .setNegativeButton(R.string.not_now, null)

                .setPositiveButton(R.string.enable, new DialogInterface.OnClickListener() {

                    @Override

                    public void onClick(DialogInterface dialog, int which) {

                        final Intent intent = CompatUtils.getInputLanguageSelectionIntent(

                                ImfUtils.getInputMethodIdOfThisIme(getActivity()),

                                Intent.FLAG_ACTIVITY_NEW_TASK

                                | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED

                                | Intent.FLAG_ACTIVITY_CLEAR_TOP);

                        // TODO: Add newly adding subtype to extra value of the intent as a hint

                        // for the input language selection activity.

                        // intent.putExtra("newlyAddedSubtype", subtypePref.getSubtype());

                        startActivity(intent);

                    }

                });

        return builder.create();

    }

    private void setPrefSubtypes(String prefSubtypes, Context context) {

        final PreferenceGroup group = getPreferenceScreen();

        group.removeAll();

        } finally {

            editor.apply();

        }

        setAdditionalInputMethodSubtypes(prefSubtypes);

    }

    private void setAdditionalInputMethodSubtypes(final String prefSubtypes) {

        final InputMethodSubtype[] subtypes =

                AdditionalSubtype.createAdditionalSubtypesArray(prefSubtypes);

        ImfUtils.setAdditionalInputMethodSubtypes(getActivity(), subtypes);