a11y: Clean up magnification mode controller and fix lint errors

This cleans up the magnification mode controller and related code. It
also fixes most of the lint errors in the files.

NO_IFTTT=linter not working

Bug: b/388335935
Flag: EXEMPT refactor
Test: com.android.settings.accessibility.ToggleScreenMagnificationPreferenceFragmentTest & com.android.settings.accessibility.MagnificationModePreferenceControllerTest
Change-Id: I368128c3c71285a9511a7831e1d01232e7536d2f

src/com/android/settings/accessibility/AccessibilityDialogUtils.java

@@ -24,6 +24,7 @@ import android.content.DialogInterface;
 import android.view.View;
 import android.widget.AbsListView;
 import android.widget.AdapterView;
+import android.widget.ListAdapter;
 import android.widget.ListView;
 import android.widget.ScrollView;
 
@@ -34,14 +35,15 @@ import androidx.appcompat.app.AlertDialog;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.List;
+import java.util.Optional;
 
 /**
  * Utility class for creating the edit dialog.
  */
 public class AccessibilityDialogUtils {
-    private static final String TAG = "AccessibilityDialogUtils";
+    private static final String TAG = AccessibilityDialogUtils.class.getSimpleName();
 
-    /** Denotes the dialog emuns for show dialog. */
+    /** Denotes the dialog enums for show dialog. */
     @Retention(RetentionPolicy.SOURCE)
     public @interface DialogEnums {
         /**
@@ -89,6 +91,19 @@ public class AccessibilityDialogUtils {
          * OPEN: Settings > Accessibility > Display size and text > Click 'Reset settings' button.
          */
         int DIALOG_RESET_SETTINGS = 1009;
+
+        /**
+         * OPEN: Settings > Accessibility > Magnification > Magnification type.
+         */
+        int DIALOG_MAGNIFICATION_MODE = 1010;
+
+        /**
+         * Enable: Settings > Accessibility > Magnification > Magnification shortcut > Advanced >
+         * Triple tap.
+         * OPEN: Settings > Accessibility > Magnification > Magnification type > Magnify part of
+         * screen / Switch between full and partial screen > Save.
+         */
+        int DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING = 1011;
     }
 
     /**
@@ -118,17 +133,26 @@ public class AccessibilityDialogUtils {
      *                         is clicked
      * @return the {@link Dialog} with the given view
      */
-    public static Dialog createCustomDialog(Context context, CharSequence dialogTitle,
+    @NonNull
-            View customView, CharSequence positiveButtonText,
+    public static Dialog createCustomDialog(@NonNull Context context,
-            DialogInterface.OnClickListener positiveListener, CharSequence negativeButtonText,
+            @NonNull CharSequence dialogTitle, @Nullable View customView,
-            DialogInterface.OnClickListener negativeListener) {
+            @NonNull CharSequence positiveButtonText,
-        final AlertDialog alertDialog = new AlertDialog.Builder(context)
+            @Nullable DialogInterface.OnClickListener positiveListener,
-                .setView(customView)
+            @NonNull CharSequence negativeButtonText,
+            @Nullable DialogInterface.OnClickListener negativeListener) {
+        DialogInterface.OnClickListener doNothingListener =
+                (DialogInterface dialogInterface, int which) -> {};
+        final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(context)
                 .setTitle(dialogTitle)
                 .setCancelable(true)
-                .setPositiveButton(positiveButtonText, positiveListener)
+                .setPositiveButton(positiveButtonText,
-                .setNegativeButton(negativeButtonText, negativeListener)
+                        Optional.ofNullable(positiveListener).orElse(doNothingListener))
-                .create();
+                .setNegativeButton(negativeButtonText,
+                        Optional.ofNullable(negativeListener).orElse(doNothingListener));
+        if (customView != null) {
+            dialogBuilder.setView(customView);
+        }
+        final AlertDialog alertDialog = dialogBuilder.create();
         if (customView instanceof ScrollView || customView instanceof AbsListView) {
             setScrollIndicators(customView);
         }
@@ -151,8 +175,7 @@ public class AccessibilityDialogUtils {
         list.setId(android.R.id.list);
         list.setDivider(/* divider= */ null);
         list.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
-        final ItemInfoArrayAdapter
+        final ListAdapter adapter = new ItemInfoArrayAdapter<>(context, itemInfoList);
-                adapter = new ItemInfoArrayAdapter(context, itemInfoList);
         list.setAdapter(adapter);
         list.setOnItemClickListener(itemListener);
         return list;

src/com/android/settings/accessibility/DialogHelper.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2025 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 com.android.settings.accessibility;
+
+/**
+ * The {@code DialogHelper} interface provides methods for displaying dialogs.
+ * It helps the dialog delegate to show the dialog, and will be injected to the dialog delegate.
+ */
+public interface DialogHelper {
+    /**
+     * Shows a dialog with the specified dialog ID.
+     *
+     * @param dialogId The ID of the dialog to display.
+     */
+    void showDialog(int dialogId);
+}

src/com/android/settings/accessibility/MagnificationModePreferenceController.java

@@ -37,11 +37,13 @@ import androidx.annotation.DrawableRes;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
+import androidx.core.util.Preconditions;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceScreen;
 
 import com.android.settings.DialogCreatable;
 import com.android.settings.R;
+import com.android.settings.accessibility.AccessibilityDialogUtils.DialogEnums;
 import com.android.settings.accessibility.MagnificationCapabilities.MagnificationMode;
 import com.android.settings.core.BasePreferenceController;
 import com.android.settings.utils.AnnotationSpan;
@@ -57,33 +59,37 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
         DialogCreatable, LifecycleObserver, OnCreate, OnSaveInstanceState {
 
     static final String PREF_KEY = "screen_magnification_mode";
-    private static final int DIALOG_ID_BASE = 10;
-    @VisibleForTesting
-    static final int DIALOG_MAGNIFICATION_MODE = DIALOG_ID_BASE + 1;
-    @VisibleForTesting
-    static final int DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING = DIALOG_ID_BASE + 2;
-    @VisibleForTesting
     static final String EXTRA_MODE = "mode";
 
-    private static final String TAG = "MagnificationModePreferenceController";
+    private static final String TAG = MagnificationModePreferenceController.class.getSimpleName();
 
+    @Nullable
     private DialogHelper mDialogHelper;
     // The magnification mode in the dialog.
     @MagnificationMode
     private int mModeCache = MagnificationMode.NONE;
+    @Nullable
     private Preference mModePreference;
+    @Nullable
     private ShortcutPreference mLinkPreference;
 
     @VisibleForTesting
+    @Nullable
     ListView mMagnificationModesListView;
 
     private final List<MagnificationModeInfo> mModeInfos = new ArrayList<>();
 
-    public MagnificationModePreferenceController(Context context, String preferenceKey) {
+    public MagnificationModePreferenceController(@NonNull Context context,
+            @NonNull String preferenceKey) {
         super(context, preferenceKey);
         initModeInfos();
     }
 
+
+    public void setDialogHelper(@NonNull DialogHelper dialogHelper) {
+        mDialogHelper = dialogHelper;
+    }
+
     private void initModeInfos() {
         mModeInfos.add(new MagnificationModeInfo(mContext.getText(
                 R.string.accessibility_magnification_mode_dialog_option_full_screen), null,
@@ -103,6 +109,7 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
         return AVAILABLE;
     }
 
+    @NonNull
     @Override
     public CharSequence getSummary() {
         final int capabilities = MagnificationCapabilities.getCapabilities(mContext);
@@ -110,99 +117,98 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
     }
 
     @Override
-    public void onCreate(Bundle savedInstanceState) {
+    public void onCreate(@Nullable Bundle savedInstanceState) {
         if (savedInstanceState != null) {
             mModeCache = savedInstanceState.getInt(EXTRA_MODE, MagnificationMode.NONE);
         }
     }
 
     @Override
-    public void displayPreference(PreferenceScreen screen) {
+    public void displayPreference(@NonNull PreferenceScreen screen) {
         super.displayPreference(screen);
         mModePreference = screen.findPreference(getPreferenceKey());
         mLinkPreference = screen.findPreference(
                 ToggleFeaturePreferenceFragment.KEY_SHORTCUT_PREFERENCE);
-        mModePreference.setOnPreferenceClickListener(preference -> {
+        Preconditions.checkNotNull(mModePreference).setOnPreferenceClickListener(preference -> {
             mModeCache = MagnificationCapabilities.getCapabilities(mContext);
-            mDialogHelper.showDialog(DIALOG_MAGNIFICATION_MODE);
+            Preconditions.checkNotNull(mDialogHelper).showDialog(
+                    DialogEnums.DIALOG_MAGNIFICATION_MODE);
             return true;
         });
     }
 
     @Override
-    public void onSaveInstanceState(Bundle outState) {
+    public void onSaveInstanceState(@NonNull Bundle outState) {
         outState.putInt(EXTRA_MODE, mModeCache);
     }
 
-    /**
+    @NonNull
-     * Sets {@link DialogHelper} used to show the dialog.
-     */
-    public void setDialogHelper(DialogHelper dialogHelper) {
-        mDialogHelper = dialogHelper;
-        mDialogHelper.setDialogDelegate(this);
-    }
-
     @Override
     public Dialog onCreateDialog(int dialogId) {
-        switch (dialogId) {
+        return switch (dialogId) {
-            case DIALOG_MAGNIFICATION_MODE:
+            case DialogEnums.DIALOG_MAGNIFICATION_MODE -> createMagnificationModeDialog();
-                return createMagnificationModeDialog();
+            case DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING ->
-
+                    createMagnificationTripleTapWarningDialog();
-            case DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING:
+            default -> throw new IllegalArgumentException(
-                return createMagnificationTripleTapWarningDialog();
+                    "This only handles magnification mode and triple tap warning dialog");
-        }
+        };
-        return null;
     }
 
     @Override
     public int getDialogMetricsCategory(int dialogId) {
-        switch (dialogId) {
+        return switch (dialogId) {
-            case DIALOG_MAGNIFICATION_MODE:
+            case DialogEnums.DIALOG_MAGNIFICATION_MODE ->
-                return SettingsEnums.DIALOG_MAGNIFICATION_CAPABILITY;
+                    SettingsEnums.DIALOG_MAGNIFICATION_CAPABILITY;
-            case DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING:
+            case DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING ->
-                return SettingsEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING;
+                    SettingsEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING;
-            default:
+            default -> 0;
-                return 0;
+        };
-        }
     }
 
+    @NonNull
+    private ListView getMagnificationModesListView() {
+        return Preconditions.checkNotNull(mMagnificationModesListView);
+    }
+
+    @NonNull
     private Dialog createMagnificationModeDialog() {
         mMagnificationModesListView = AccessibilityDialogUtils.createSingleChoiceListView(
                 mContext, mModeInfos, this::onMagnificationModeSelected);
 
         final View headerView = LayoutInflater.from(mContext).inflate(
-                R.layout.accessibility_magnification_mode_header, mMagnificationModesListView,
+                R.layout.accessibility_magnification_mode_header,
-                false);
+                getMagnificationModesListView(), /* attachToRoot= */false);
-        mMagnificationModesListView.addHeaderView(headerView, /* data= */ null, /* isSelectable= */
+        getMagnificationModesListView().addHeaderView(headerView, /* data= */null,
-                false);
+                /* isSelectable= */false);
 
-        mMagnificationModesListView.setItemChecked(computeSelectionIndex(), true);
+        getMagnificationModesListView().setItemChecked(computeSelectionIndex(), /* value= */true);
         final CharSequence title = mContext.getString(
                 R.string.accessibility_magnification_mode_dialog_title);
         final CharSequence positiveBtnText = mContext.getString(R.string.save);
         final CharSequence negativeBtnText = mContext.getString(R.string.cancel);
 
         return AccessibilityDialogUtils.createCustomDialog(mContext, title,
-                mMagnificationModesListView,
+                getMagnificationModesListView(), positiveBtnText,
-                positiveBtnText, this::onMagnificationModeDialogPositiveButtonClicked,
+                this::onMagnificationModeDialogPositiveButtonClicked,
                 negativeBtnText, /* negativeListener= */null);
     }
 
     @VisibleForTesting
-    void onMagnificationModeDialogPositiveButtonClicked(DialogInterface dialogInterface,
+    void onMagnificationModeDialogPositiveButtonClicked(@NonNull DialogInterface dialogInterface,
             int which) {
-        final int selectedIndex = mMagnificationModesListView.getCheckedItemPosition();
+        final int selectedIndex = getMagnificationModesListView().getCheckedItemPosition();
         if (selectedIndex == AdapterView.INVALID_POSITION) {
-            Log.w(TAG, "invalid index");
+            Log.w(TAG, "Selected positive button with INVALID_POSITION index");
             return;
         }
 
-        mModeCache = ((MagnificationModeInfo) mMagnificationModesListView.getItemAtPosition(
+        mModeCache = ((MagnificationModeInfo) getMagnificationModesListView().getItemAtPosition(
                 selectedIndex)).mMagnificationMode;
 
         // Do not save mode until user clicks positive button in triple tap warning dialog.
         if (isTripleTapEnabled(mContext) && mModeCache != MagnificationMode.FULLSCREEN) {
-            mDialogHelper.showDialog(DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
+            Preconditions.checkNotNull(mDialogHelper).showDialog(
+                    DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
         } else { // Save mode (capabilities) value, don't need to show dialog to confirm.
             updateCapabilitiesAndSummary(mModeCache);
         }
@@ -211,15 +217,14 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
     private void updateCapabilitiesAndSummary(@MagnificationMode int mode) {
         mModeCache = mode;
         MagnificationCapabilities.setCapabilities(mContext, mModeCache);
-        mModePreference.setSummary(
+        Preconditions.checkNotNull(mModePreference).setSummary(
                 MagnificationCapabilities.getSummary(mContext, mModeCache));
     }
 
-    private void onMagnificationModeSelected(AdapterView<?> parent, View view, int position,
+    private void onMagnificationModeSelected(@NonNull AdapterView<?> parent, @NonNull View view,
-            long id) {
+            int position, long id) {
         final MagnificationModeInfo modeInfo =
-                (MagnificationModeInfo) mMagnificationModesListView.getItemAtPosition(
+                (MagnificationModeInfo) getMagnificationModesListView().getItemAtPosition(position);
-                        position);
         if (modeInfo.mMagnificationMode == mModeCache) {
             return;
         }
@@ -230,20 +235,22 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
         final int modesSize = mModeInfos.size();
         for (int i = 0; i < modesSize; i++) {
             if (mModeInfos.get(i).mMagnificationMode == mModeCache) {
-                return i + mMagnificationModesListView.getHeaderViewsCount();
+                return i + getMagnificationModesListView().getHeaderViewsCount();
             }
         }
-        Log.w(TAG, "computeSelectionIndex failed");
+        Log.w(TAG, "Can not find matching mode in mModeInfos");
         return 0;
     }
 
     @VisibleForTesting
-    static boolean isTripleTapEnabled(Context context) {
+    static boolean isTripleTapEnabled(@NonNull Context context) {
         return Settings.Secure.getInt(context.getContentResolver(),
                 Settings.Secure.ACCESSIBILITY_DISPLAY_MAGNIFICATION_ENABLED, OFF) == ON;
     }
 
+    @NonNull
     private Dialog createMagnificationTripleTapWarningDialog() {
+        @SuppressWarnings({"InflateParams"})
         final View contentView = LayoutInflater.from(mContext).inflate(
                 R.layout.magnification_triple_tap_warning_dialog, /* root= */ null);
         final CharSequence title = mContext.getString(
@@ -263,12 +270,13 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
         return dialog;
     }
 
-    private void updateLinkInTripleTapWarningDialog(Dialog dialog, View contentView) {
+    private void updateLinkInTripleTapWarningDialog(@NonNull Dialog dialog,
+            @NonNull View contentView) {
         final TextView messageView = contentView.findViewById(R.id.message);
         // TODO(b/225682559): Need to remove performClick() after refactoring accessibility dialog.
         final View.OnClickListener linkListener = view -> {
             updateCapabilitiesAndSummary(mModeCache);
-            mLinkPreference.performClick();
+            Preconditions.checkNotNull(mLinkPreference).performClick();
             dialog.dismiss();
         };
         final AnnotationSpan.LinkInfo linkInfo = new AnnotationSpan.LinkInfo(
@@ -285,25 +293,18 @@ public class MagnificationModePreferenceController extends BasePreferenceControl
 
     @VisibleForTesting
     void onMagnificationTripleTapWarningDialogNegativeButtonClicked(
-            DialogInterface dialogInterface, int which) {
+            @NonNull DialogInterface dialogInterface, int which) {
         mModeCache = MagnificationCapabilities.getCapabilities(mContext);
-        mDialogHelper.showDialog(DIALOG_MAGNIFICATION_MODE);
+        Preconditions.checkNotNull(mDialogHelper).showDialog(
+                DialogEnums.DIALOG_MAGNIFICATION_MODE);
     }
 
     @VisibleForTesting
     void onMagnificationTripleTapWarningDialogPositiveButtonClicked(
-            DialogInterface dialogInterface, int which) {
+            @NonNull DialogInterface dialogInterface, int which) {
         updateCapabilitiesAndSummary(mModeCache);
     }
 
-    /**
-     * An interface to help the delegate to show the dialog. It will be injected to the delegate.
-     */
-    interface DialogHelper extends DialogCreatable {
-        void showDialog(int dialogId);
-        void setDialogDelegate(DialogCreatable delegate);
-    }
-
     @VisibleForTesting
     static class MagnificationModeInfo extends ItemInfoArrayAdapter.ItemInfo {
         @MagnificationMode

src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragment.java

@@ -19,7 +19,6 @@ package com.android.settings.accessibility;
 import static com.android.internal.accessibility.AccessibilityShortcutController.MAGNIFICATION_COMPONENT_NAME;
 import static com.android.internal.accessibility.AccessibilityShortcutController.MAGNIFICATION_CONTROLLER_NAME;
 import static com.android.internal.accessibility.common.ShortcutConstants.UserShortcutType.DEFAULT;
-import static com.android.settings.accessibility.AccessibilityDialogUtils.DialogEnums;
 import static com.android.settings.accessibility.AccessibilityUtil.State.OFF;
 import static com.android.settings.accessibility.AccessibilityUtil.State.ON;
 import static com.android.settings.accessibility.AccessibilityUtil.getShortcutSummaryList;
@@ -42,8 +41,10 @@ import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityManager;
 import android.view.accessibility.AccessibilityManager.TouchExplorationStateChangeListener;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.StringRes;
+import androidx.core.util.Preconditions;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceCategory;
 import androidx.preference.SwitchPreferenceCompat;
@@ -53,6 +54,7 @@ import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.accessibility.Flags;
 import com.android.settings.DialogCreatable;
 import com.android.settings.R;
+import com.android.settings.accessibility.AccessibilityDialogUtils.DialogEnums;
 import com.android.settings.accessibility.shortcuts.EditShortcutsPreferenceFragment;
 import com.android.settings.search.BaseSearchIndexProvider;
 import com.android.settingslib.core.AbstractPreferenceController;
@@ -74,10 +76,10 @@ import java.util.stream.Stream;
  */
 @SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
 public class ToggleScreenMagnificationPreferenceFragment extends
-        ToggleFeaturePreferenceFragment implements
+        ToggleFeaturePreferenceFragment implements DialogHelper {
-        MagnificationModePreferenceController.DialogHelper {
 
-    private static final String TAG = "ToggleScreenMagnificationPreferenceFragment";
+    private static final String TAG =
+            ToggleScreenMagnificationPreferenceFragment.class.getSimpleName();
     @VisibleForTesting
     static final String KEY_MAGNIFICATION_SHORTCUT_PREFERENCE = "magnification_shortcut_preference";
     private static final char COMPONENT_NAME_SEPARATOR = ':';
@@ -86,23 +88,30 @@ public class ToggleScreenMagnificationPreferenceFragment extends
 
     // TODO(b/147021230): Move duplicated functions with android/internal/accessibility into util.
     private TouchExplorationStateChangeListener mTouchExplorationStateChangeListener;
-    private DialogCreatable mDialogDelegate;
+    @Nullable
+    private DialogCreatable mMagnificationModeDialogDelegate;
 
     @Nullable
     MagnificationOneFingerPanningPreferenceController mOneFingerPanningPreferenceController;
 
     private boolean mInSetupWizard;
 
+    @VisibleForTesting
+    public void setMagnificationModeDialogDelegate(@NonNull DialogCreatable delegate) {
+        mMagnificationModeDialogDelegate = delegate;
+    }
+
     @Override
-    public void onCreate(Bundle savedInstanceState) {
+    public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         getActivity().setTitle(R.string.accessibility_screen_magnification_title);
         mInSetupWizard = WizardManagerHelper.isAnySetupWizard(getIntent());
     }
 
+    @NonNull
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container,
+    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
-            Bundle savedInstanceState) {
+            @NonNull Bundle savedInstanceState) {
         mFeatureName = getString(R.string.accessibility_screen_magnification_title);
         mImageUri = new Uri.Builder().scheme(ContentResolver.SCHEME_ANDROID_RESOURCE)
                 .authority(getPrefContext().getPackageName())
@@ -161,15 +170,14 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         super.onPause();
     }
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(int dialogId) {
-        if (mDialogDelegate != null) {
-            mDialog = mDialogDelegate.onCreateDialog(dialogId);
-            if (mDialog != null) {
-                return mDialog;
-            }
-        }
         switch (dialogId) {
+            case DialogEnums.DIALOG_MAGNIFICATION_MODE:
+            case DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING:
+                return Preconditions.checkNotNull(mMagnificationModeDialogDelegate)
+                        .onCreateDialog(dialogId);
             case DialogEnums.GESTURE_NAVIGATION_TUTORIAL:
                 return AccessibilityShortcutsTutorial
                         .showAccessibilityGestureTutorialDialog(getPrefContext());
@@ -238,9 +246,10 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         generalCategory.addPreference(mSettingsPreference);
 
         final MagnificationModePreferenceController magnificationModePreferenceController =
-                new MagnificationModePreferenceController(getContext(),
+                new MagnificationModePreferenceController(Preconditions.checkNotNull(getContext()),
                         MagnificationModePreferenceController.PREF_KEY);
-        magnificationModePreferenceController.setDialogHelper(this);
+        magnificationModePreferenceController.setDialogHelper(/* dialogHelper= */this);
+        mMagnificationModeDialogDelegate = magnificationModePreferenceController;
         getSettingsLifecycle().addObserver(magnificationModePreferenceController);
         magnificationModePreferenceController.displayPreference(getPreferenceScreen());
         addPreferenceController(magnificationModePreferenceController);
@@ -388,11 +397,6 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         super.showDialog(dialogId);
     }
 
-    @Override
-    public void setDialogDelegate(DialogCreatable delegate) {
-        mDialogDelegate = delegate;
-    }
-
     @Override
     protected void registerKeysToObserverCallback(
             AccessibilitySettingsContentObserver contentObserver) {
@@ -470,14 +474,11 @@ public class ToggleScreenMagnificationPreferenceFragment extends
 
     @Override
     public int getDialogMetricsCategory(int dialogId) {
-        if (mDialogDelegate != null) {
-            final int category = mDialogDelegate.getDialogMetricsCategory(dialogId);
-            if (category != 0) {
-                return category;
-            }
-        }
-
         switch (dialogId) {
+            case DialogEnums.DIALOG_MAGNIFICATION_MODE:
+            case DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING:
+                return Preconditions.checkNotNull(mMagnificationModeDialogDelegate)
+                        .getDialogMetricsCategory(dialogId);
             case DialogEnums.GESTURE_NAVIGATION_TUTORIAL:
                 return SettingsEnums.DIALOG_TOGGLE_SCREEN_MAGNIFICATION_GESTURE_NAVIGATION;
             case DialogEnums.ACCESSIBILITY_BUTTON_TUTORIAL:
@@ -514,7 +515,7 @@ public class ToggleScreenMagnificationPreferenceFragment extends
     }
 
     @Override
-    public void onToggleClicked(ShortcutPreference preference) {
+    public void onToggleClicked(@NonNull ShortcutPreference preference) {
         final int shortcutTypes = getUserPreferredShortcutTypes();
         getPrefContext().getSystemService(AccessibilityManager.class).enableShortcutsForTargets(
                 preference.isChecked(), shortcutTypes,
@@ -527,7 +528,7 @@ public class ToggleScreenMagnificationPreferenceFragment extends
     }
 
     @Override
-    public void onSettingsClicked(ShortcutPreference preference) {
+    public void onSettingsClicked(@NonNull ShortcutPreference preference) {
         EditShortcutsPreferenceFragment.showEditShortcutScreen(
                 requireContext(),
                 getMetricsCategory(),
@@ -581,7 +582,8 @@ public class ToggleScreenMagnificationPreferenceFragment extends
      *
      * @param context The current context.
      */
-    public static CharSequence getServiceSummary(Context context) {
+    @NonNull
+    public static CharSequence getServiceSummary(@NonNull Context context) {
         // Get the user shortcut type from settings provider.
         final int userShortcutType = ShortcutUtils.getEnabledShortcutTypes(
                 context, MAGNIFICATION_CONTROLLER_NAME);
@@ -604,8 +606,9 @@ public class ToggleScreenMagnificationPreferenceFragment extends
     public static final Indexable.SearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
             new BaseSearchIndexProvider() {
                 // LINT.IfChange(search_data)
+                @NonNull
                 @Override
-                public List<SearchIndexableRaw> getRawDataToIndex(Context context,
+                public List<SearchIndexableRaw> getRawDataToIndex(@NonNull Context context,
                         boolean enabled) {
                     final List<SearchIndexableRaw> rawData =
                             super.getRawDataToIndex(context, enabled);
@@ -628,8 +631,9 @@ public class ToggleScreenMagnificationPreferenceFragment extends
                     return rawData;
                 }
 
+                @NonNull
                 @Override
-                public List<String> getNonIndexableKeys(Context context) {
+                public List<String> getNonIndexableKeys(@NonNull Context context) {
                     final List<String> niks = super.getNonIndexableKeys(context);
 
                     if (!com.android.settings.accessibility.Flags.fixA11ySettingsSearch()) {

tests/robotests/src/com/android/settings/accessibility/MagnificationModePreferenceControllerTest.java

@@ -17,8 +17,6 @@
 package com.android.settings.accessibility;
 
 import static com.android.settings.accessibility.AccessibilityUtil.State.ON;
-import static com.android.settings.accessibility.MagnificationCapabilities.MagnificationMode;
-import static com.android.settings.accessibility.MagnificationModePreferenceController.MagnificationModeInfo;
 
 import static com.google.common.truth.Truth.assertThat;
 
@@ -37,6 +35,7 @@ import android.widget.AdapterView;
 import android.widget.ListView;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceManager;
 import androidx.preference.PreferenceScreen;
@@ -44,6 +43,9 @@ import androidx.test.core.app.ApplicationProvider;
 
 import com.android.settings.DialogCreatable;
 import com.android.settings.R;
+import com.android.settings.accessibility.AccessibilityDialogUtils.DialogEnums;
+import com.android.settings.accessibility.MagnificationCapabilities.MagnificationMode;
+import com.android.settings.accessibility.MagnificationModePreferenceController.MagnificationModeInfo;
 import com.android.settings.utils.AnnotationSpan;
 
 import org.junit.Before;
@@ -82,6 +84,8 @@ public class MagnificationModePreferenceControllerTest {
         mScreen.addPreference(mModePreference);
         MagnificationCapabilities.setCapabilities(mContext, MAGNIFICATION_MODE_DEFAULT);
         mController = new MagnificationModePreferenceController(mContext, PREF_KEY);
+        mController.setDialogHelper(mDialogHelper);
+        mDialogHelper.setDialogDelegate(mController);
         showPreferenceOnTheScreen(null);
     }
 
@@ -107,7 +111,7 @@ public class MagnificationModePreferenceControllerTest {
         performItemClickWith(MagnificationMode.WINDOW);
 
         reshowPreferenceOnTheScreen();
-        mDialogHelper.showDialog(MagnificationModePreferenceController.DIALOG_MAGNIFICATION_MODE);
+        mDialogHelper.showDialog(DialogEnums.DIALOG_MAGNIFICATION_MODE);
 
         assertThat(getCheckedModeFromDialog()).isEqualTo(
                 MagnificationMode.WINDOW);
@@ -123,7 +127,7 @@ public class MagnificationModePreferenceControllerTest {
                 DialogInterface.BUTTON_POSITIVE);
 
         verify(mDialogHelper, never()).showDialog(
-                MagnificationModePreferenceController.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
+                DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
     }
 
     @Test
@@ -135,8 +139,7 @@ public class MagnificationModePreferenceControllerTest {
         mController.onMagnificationModeDialogPositiveButtonClicked(mDialogHelper.getDialog(),
                 DialogInterface.BUTTON_POSITIVE);
 
-        verify(mDialogHelper).showDialog(
+        verify(mDialogHelper).showDialog(DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
-                MagnificationModePreferenceController.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
     }
 
     @Test
@@ -148,20 +151,17 @@ public class MagnificationModePreferenceControllerTest {
         mController.onMagnificationModeDialogPositiveButtonClicked(mDialogHelper.getDialog(),
                 DialogInterface.BUTTON_POSITIVE);
 
-        verify(mDialogHelper).showDialog(
+        verify(mDialogHelper).showDialog(DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
-                MagnificationModePreferenceController.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
     }
 
     @Test
     public void onTripleTapWarningDialogNegativeButtonClicked_showModeDialog() {
-        mDialogHelper.showDialog(
+        mDialogHelper.showDialog(DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
-                MagnificationModePreferenceController.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
 
         mController.onMagnificationTripleTapWarningDialogNegativeButtonClicked(
                 mDialogHelper.getDialog(), DialogInterface.BUTTON_NEGATIVE);
 
-        verify(mDialogHelper).showDialog(
+        verify(mDialogHelper).showDialog(DialogEnums.DIALOG_MAGNIFICATION_MODE);
-                MagnificationModePreferenceController.DIALOG_MAGNIFICATION_MODE);
     }
 
     @Test
@@ -182,8 +182,7 @@ public class MagnificationModePreferenceControllerTest {
 
     @Test
     public void checkSpansInTripleTapWarningDialog_existAnnotationSpan() {
-        mDialogHelper.showDialog(
+        mDialogHelper.showDialog(DialogEnums.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
-                MagnificationModePreferenceController.DIALOG_MAGNIFICATION_TRIPLE_TAP_WARNING);
         final View contentView = mDialogHelper.getDialog().findViewById(android.R.id.content);
         final TextView messageView = contentView.findViewById(R.id.message);
         final CharSequence textInTripleTapWarningDialog = messageView.getText();
@@ -256,13 +255,11 @@ public class MagnificationModePreferenceControllerTest {
     }
 
     private void showPreferenceOnTheScreen(Bundle savedInstanceState) {
-        mController.setDialogHelper(mDialogHelper);
         mController.onCreate(savedInstanceState);
         mController.displayPreference(mScreen);
     }
 
-    private static class TestDialogHelper implements DialogCreatable,
+    private static class TestDialogHelper implements DialogCreatable, DialogHelper {
-            MagnificationModePreferenceController.DialogHelper {
         private DialogCreatable mDialogDelegate;
         private Dialog mDialog;
 
@@ -271,11 +268,11 @@ public class MagnificationModePreferenceControllerTest {
             mDialog = onCreateDialog(dialogId);
         }
 
-        @Override
+        public void setDialogDelegate(@NonNull DialogCreatable delegate) {
-        public void setDialogDelegate(DialogCreatable delegate) {
             mDialogDelegate = delegate;
         }
 
+        @NonNull
         @Override
         public Dialog onCreateDialog(int dialogId) {
             return mDialogDelegate.onCreateDialog(dialogId);

tests/robotests/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragmentTest.java

@@ -64,6 +64,8 @@ import com.android.server.accessibility.Flags;
 import com.android.settings.DialogCreatable;
 import com.android.settings.R;
 import com.android.settings.SettingsActivity;
+import com.android.settings.accessibility.AccessibilityDialogUtils.DialogEnums;
+import com.android.settings.accessibility.MagnificationCapabilities.MagnificationMode;
 import com.android.settings.testutils.shadow.ShadowAccessibilityManager;
 import com.android.settings.testutils.shadow.ShadowDeviceConfig;
 import com.android.settings.testutils.shadow.ShadowStorageManager;
@@ -550,7 +552,8 @@ public class ToggleScreenMagnificationPreferenceFragmentTest {
         ToggleScreenMagnificationPreferenceFragment fragment = mFragController.create(
                 R.id.main_content, /* bundle= */ null).start().resume().get();
 
-        DialogCreatable dialogDelegate = ReflectionHelpers.getField(fragment, "mDialogDelegate");
+        DialogCreatable dialogDelegate = ReflectionHelpers.getField(fragment,
+                "mMagnificationModeDialogDelegate");
         List<LifecycleObserver> lifecycleObservers = ReflectionHelpers.getField(
                 fragment.getSettingsLifecycle(), "mObservers");
         assertThat(dialogDelegate).isInstanceOf(MagnificationModePreferenceController.class);
@@ -592,19 +595,19 @@ public class ToggleScreenMagnificationPreferenceFragmentTest {
     }
 
     @Test
-    public void onCreateDialog_setDialogDelegate_invokeDialogDelegate() {
+    public void onCreateDialog_setMagnificationModeDialogDelegate_invokeDialogDelegate() {
         ToggleScreenMagnificationPreferenceFragment fragment =
                 mFragController.create(
                         R.id.main_content, /* bundle= */ null).start().resume().get();
         final DialogCreatable dialogDelegate = mock(DialogCreatable.class, RETURNS_DEEP_STUBS);
-        when(dialogDelegate.getDialogMetricsCategory(anyInt())).thenReturn(1);
+        final int dialogId = DialogEnums.DIALOG_MAGNIFICATION_MODE;
-        fragment.setDialogDelegate(dialogDelegate);
+        when(dialogDelegate.getDialogMetricsCategory(anyInt())).thenReturn(dialogId);
+        fragment.setMagnificationModeDialogDelegate(dialogDelegate);
 
-        fragment.onCreateDialog(1);
+        fragment.onCreateDialog(dialogId);
-        fragment.getDialogMetricsCategory(1);
+        fragment.getDialogMetricsCategory(dialogId);
-
+        verify(dialogDelegate).onCreateDialog(dialogId);
-        verify(dialogDelegate).onCreateDialog(1);
+        verify(dialogDelegate).getDialogMetricsCategory(dialogId);
-        verify(dialogDelegate).getDialogMetricsCategory(1);
     }
 
     @Test