diff --git a/core/java/android/app/Activity.java b/core/java/android/app/Activity.java
index d24b677..e85fa9d 100644
--- a/core/java/android/app/Activity.java
+++ b/core/java/android/app/Activity.java
@@ -959,7 +959,7 @@
     private int mDefaultKeyMode = DEFAULT_KEYS_DISABLE;
     private SpannableStringBuilder mDefaultKeySsb = null;
 
-    private ActivityManager.TaskDescription mTaskDescription =
+    private final ActivityManager.TaskDescription mTaskDescription =
             new ActivityManager.TaskDescription();
 
     protected static final int[] FOCUSED_STATE_SET = {com.android.internal.R.attr.state_focused};
@@ -970,7 +970,7 @@
     private Thread mUiThread;
 
     @UnsupportedAppUsage
-    ActivityTransitionState mActivityTransitionState = new ActivityTransitionState();
+    final ActivityTransitionState mActivityTransitionState = new ActivityTransitionState();
     SharedElementCallback mEnterTransitionListener = SharedElementCallback.NULL_CALLBACK;
     SharedElementCallback mExitTransitionListener = SharedElementCallback.NULL_CALLBACK;
 
@@ -1839,7 +1839,7 @@
         final int numDialogs = ids.length;
         mManagedDialogs = new SparseArray<ManagedDialog>(numDialogs);
         for (int i = 0; i < numDialogs; i++) {
-            final Integer dialogId = ids[i];
+            final int dialogId = ids[i];
             Bundle dialogState = b.getBundle(savedDialogKeyFor(dialogId));
             if (dialogState != null) {
                 // Calling onRestoreInstanceState() below will invoke dispatchOnCreate
@@ -1909,7 +1909,7 @@
      * <code>persistAcrossReboots</code>.
      *
      * @param savedInstanceState The data most recently supplied in {@link #onSaveInstanceState}
-     * @param persistentState The data caming from the PersistableBundle first
+     * @param persistentState The data coming from the PersistableBundle first
      * saved in {@link #onSaveInstanceState(Bundle, PersistableBundle)}.
      *
      * @see #onCreate
@@ -5058,7 +5058,7 @@
      * This hook is called when the user signals the desire to start a search.
      *
      * <p>You can use this function as a simple way to launch the search UI, in response to a
-     * menu item, search button, or other widgets within your activity. Unless overidden,
+     * menu item, search button, or other widgets within your activity. Unless overridden,
      * calling this function is the same as calling
      * {@link #startSearch startSearch(null, false, null, false)}, which launches
      * search for the current activity as specified in its manifest, see {@link SearchManager}.
@@ -8797,7 +8797,7 @@
          * @see Activity#convertFromTranslucent()
          * @see Activity#convertToTranslucent(TranslucentConversionListener, ActivityOptions)
          */
-        public void onTranslucentConversionComplete(boolean drawComplete);
+        void onTranslucentConversionComplete(boolean drawComplete);
     }
 
     private void dispatchRequestPermissionsResult(int requestCode, Intent data) {
@@ -8920,7 +8920,7 @@
     /**
      * Registers remote animations per transition type for this activity.
      *
-     * @param definition The remote animation definition that defines which transition whould run
+     * @param definition The remote animation definition that defines which transition would run
      *                   which remote animation.
      * @hide
      */
diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index 5ba7a4c..a1e4dbf 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -266,7 +266,6 @@
         implements ActivityThreadInternal {
     /** @hide */
     public static final String TAG = "ActivityThread";
-    private static final android.graphics.Bitmap.Config THUMBNAIL_FORMAT = Bitmap.Config.RGB_565;
     static final boolean localLOGV = false;
     static final boolean DEBUG_MESSAGES = false;
     /** @hide */
@@ -368,7 +367,7 @@
     private final AtomicInteger mNumLaunchingActivities = new AtomicInteger();
     @GuardedBy("mAppThread")
     private int mLastProcessState = PROCESS_STATE_UNKNOWN;
-    ArrayList<WeakReference<AssistStructure>> mLastAssistStructures = new ArrayList<>();
+    final ArrayList<WeakReference<AssistStructure>> mLastAssistStructures = new ArrayList<>();
     private int mLastSessionId;
     final ArrayMap<IBinder, CreateServiceData> mServicesData = new ArrayMap<>();
     @UnsupportedAppUsage
@@ -564,7 +563,7 @@
         Configuration createdConfig;
         Configuration overrideConfig;
         // Used for consolidating configs before sending on to Activity.
-        private Configuration tmpConfig = new Configuration();
+        private final Configuration tmpConfig = new Configuration();
         // Callback used for updating activity override config and camera compat control state.
         ViewRootImpl.ActivityConfigCallback activityConfigCallback;
         ActivityClientRecord nextIdle;
@@ -769,7 +768,7 @@
         }
     }
 
-    final class ProviderClientRecord {
+    static final class ProviderClientRecord {
         final String[] mNames;
         @UnsupportedAppUsage
         final IContentProvider mProvider;
@@ -796,7 +795,7 @@
         }
 
         @UnsupportedAppUsage
-        Intent intent;
+        final Intent intent;
         @UnsupportedAppUsage
         ActivityInfo info;
         @UnsupportedAppUsage
@@ -3336,11 +3335,8 @@
     public void registerOnActivityPausedListener(Activity activity,
             OnActivityPausedListener listener) {
         synchronized (mOnPauseListeners) {
-            ArrayList<OnActivityPausedListener> list = mOnPauseListeners.get(activity);
-            if (list == null) {
-                list = new ArrayList<OnActivityPausedListener>();
-                mOnPauseListeners.put(activity, list);
-            }
+            ArrayList<OnActivityPausedListener> list =
+                    mOnPauseListeners.computeIfAbsent(activity, k -> new ArrayList<>());
             list.add(listener);
         }
     }
@@ -5400,7 +5396,7 @@
     /** Core implementation of activity destroy call. */
     void performDestroyActivity(ActivityClientRecord r, boolean finishing,
             int configChanges, boolean getNonConfigInstance, String reason) {
-        Class<? extends Activity> activityClass = null;
+        Class<? extends Activity> activityClass;
         if (localLOGV) Slog.v(TAG, "Performing finish of " + r);
         activityClass = r.activity.getClass();
         r.activity.mConfigChangeFlags |= configChanges;
@@ -7051,7 +7047,7 @@
         // Note that we cannot hold the lock while acquiring and installing the
         // provider since it might take a long time to run and it could also potentially
         // be re-entrant in the case where the provider is in the same process.
-        ContentProviderHolder holder = null;
+        ContentProviderHolder holder;
         final ProviderKey key = getGetProviderKey(auth, userId);
         try {
             synchronized (key) {
@@ -7105,11 +7101,7 @@
     private ProviderKey getGetProviderKey(String auth, int userId) {
         final ProviderKey key = new ProviderKey(auth, userId);
         synchronized (mGetProviderKeys) {
-            ProviderKey lock = mGetProviderKeys.get(key);
-            if (lock == null) {
-                lock = key;
-                mGetProviderKeys.put(key, lock);
-            }
+            ProviderKey lock = mGetProviderKeys.computeIfAbsent(key, k -> k);
             return lock;
         }
     }
@@ -7744,7 +7736,7 @@
             if (!DEPRECATE_DATA_COLUMNS) return;
 
             // Install interception and make sure it sticks!
-            Os def = null;
+            Os def;
             do {
                 def = Os.getDefault();
             } while (!Os.compareAndSetDefault(def, new AndroidOs(def)));
diff --git a/core/java/android/app/AliasActivity.java b/core/java/android/app/AliasActivity.java
index 37be901..f266769 100644
--- a/core/java/android/app/AliasActivity.java
+++ b/core/java/android/app/AliasActivity.java
@@ -16,9 +16,6 @@
 
 package android.app;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
-
 import android.content.Intent;
 import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
@@ -29,13 +26,16 @@
 
 import com.android.internal.util.XmlUtils;
 
+import org.xmlpull.v1.XmlPullParser;
+import org.xmlpull.v1.XmlPullParserException;
+
 import java.io.IOException;
 
 /**
  * Stub activity that launches another activity (and then finishes itself)
  * based on information in its component's manifest meta-data.  This is a
  * simple way to implement an alias-like mechanism.
- * 
+ *
  * To use this activity, you should include in the manifest for the associated
  * component an entry named "android.app.alias".  It is a reference to an XML
  * resource describing an intent that launches the real application.
@@ -51,11 +51,11 @@
      * {@hide}
      */
     public final String ALIAS_META_DATA = "android.app.alias";
-    
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        
+
         XmlResourceParser parser = null;
         try {
             ActivityInfo ai = getPackageManager().getActivityInfo(
@@ -66,21 +66,17 @@
                 throw new RuntimeException("Alias requires a meta-data field "
                         + ALIAS_META_DATA);
             }
-            
+
             Intent intent = parseAlias(parser);
             if (intent == null) {
                 throw new RuntimeException(
                         "No <intent> tag found in alias description");
             }
-            
+
             startActivity(intent);
             finish();
-            
-        } catch (PackageManager.NameNotFoundException e) {
-            throw new RuntimeException("Error parsing alias", e);
-        } catch (XmlPullParserException e) {
-            throw new RuntimeException("Error parsing alias", e);
-        } catch (IOException e) {
+
+        } catch (PackageManager.NameNotFoundException | XmlPullParserException | IOException e) {
             throw new RuntimeException("Error parsing alias", e);
         } finally {
             if (parser != null) parser.close();
@@ -90,21 +86,21 @@
     private Intent parseAlias(XmlPullParser parser)
             throws XmlPullParserException, IOException {
         AttributeSet attrs = Xml.asAttributeSet(parser);
-        
+
         Intent intent = null;
-        
+
         int type;
         while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                 && type != XmlPullParser.START_TAG) {
         }
-        
+
         String nodeName = parser.getName();
         if (!"alias".equals(nodeName)) {
             throw new RuntimeException(
                     "Alias meta-data must start with <alias> tag; found"
                     + nodeName + " at " + parser.getPositionDescription());
         }
-        
+
         int outerDepth = parser.getDepth();
         while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                && (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
@@ -120,8 +116,8 @@
                 XmlUtils.skipCurrentTag(parser);
             }
         }
-        
+
         return intent;
     }
-    
+
 }
diff --git a/core/java/android/app/SearchableInfo.java b/core/java/android/app/SearchableInfo.java
index bd5d105..05742e6 100644
--- a/core/java/android/app/SearchableInfo.java
+++ b/core/java/android/app/SearchableInfo.java
@@ -535,7 +535,7 @@
      */
     public static SearchableInfo getActivityMetaData(Context context, ActivityInfo activityInfo,
             int userId) {
-        Context userContext = null;
+        Context userContext;
         try {
             userContext = context.createPackageContextAsUser("system", 0,
                 new UserHandle(userId));
diff --git a/core/java/android/app/WallpaperManager.java b/core/java/android/app/WallpaperManager.java
index dea1a05..75b450d 100644
--- a/core/java/android/app/WallpaperManager.java
+++ b/core/java/android/app/WallpaperManager.java
@@ -1629,7 +1629,6 @@
                     mContext.getUserId());
             if (fd != null) {
                 FileOutputStream fos = null;
-                boolean ok = false;
                 try {
                     fos = new ParcelFileDescriptor.AutoCloseOutputStream(fd);
                     copyStreamToWallpaperFile(resources.openRawResource(resid), fos);