diff --git a/src/main/java/org/thoughtcrime/securesms/components/InputPanel.java b/src/main/java/org/thoughtcrime/securesms/components/InputPanel.java
index f3b182d74..c8c0c22b9 100644
--- a/src/main/java/org/thoughtcrime/securesms/components/InputPanel.java
+++ b/src/main/java/org/thoughtcrime/securesms/components/InputPanel.java
@@ -183,7 +183,7 @@ public class InputPanel extends ConstraintLayout
     if (quoteView.getVisibility() == View.VISIBLE && quoteView.getBody() != null) {
       return Optional.of(new QuoteModel(
               quoteView.getDcContact(), quoteView.getBody().toString(),
-              false, quoteView.getAttachments(), quoteView.getOriginalMsg()
+              quoteView.getAttachments(), quoteView.getOriginalMsg()
       ));
     } else {
       return Optional.absent();
diff --git a/src/main/java/org/thoughtcrime/securesms/contacts/ContactSelectionListItem.java b/src/main/java/org/thoughtcrime/securesms/contacts/ContactSelectionListItem.java
index 0a02f6494..28d627254 100644
--- a/src/main/java/org/thoughtcrime/securesms/contacts/ContactSelectionListItem.java
+++ b/src/main/java/org/thoughtcrime/securesms/contacts/ContactSelectionListItem.java
@@ -83,7 +83,7 @@ public class ContactSelectionListItem extends LinearLayout implements RecipientM
     } else {
       this.avatar.setAvatar(glideRequests, recipient, false);
     }
-    this.avatar.setSeenRecently(contact!=null? contact.wasSeenRecently() : false);
+    this.avatar.setSeenRecently(contact != null && contact.wasSeenRecently());
 
     setText(name, number, label, contact);
     setEnabled(enabled);
@@ -110,7 +110,7 @@ public class ContactSelectionListItem extends LinearLayout implements RecipientM
     this.nameView.setText(name==null? "#" : name);
 
     if(number!=null) {
-      this.numberView.setText(number == null ? "" : number);
+      this.numberView.setText(number);
       this.labelView.setText(label==null? "" : label);
       this.numberContainer.setVisibility(View.VISIBLE);
     }
@@ -154,7 +154,7 @@ public class ContactSelectionListItem extends LinearLayout implements RecipientM
       Util.runOnMain(() -> {
         avatar.setAvatar(glideRequests, recipient, false);
         DcContact contact = recipient.getDcContact();
-        avatar.setSeenRecently(contact!=null? contact.wasSeenRecently() : false);
+        avatar.setSeenRecently(contact != null && contact.wasSeenRecently());
         nameView.setText(recipient.toShortString());
       });
     }
diff --git a/src/main/java/org/thoughtcrime/securesms/contacts/avatars/LocalFileContactPhoto.java b/src/main/java/org/thoughtcrime/securesms/contacts/avatars/LocalFileContactPhoto.java
index 2e43186cc..dac672756 100644
--- a/src/main/java/org/thoughtcrime/securesms/contacts/avatars/LocalFileContactPhoto.java
+++ b/src/main/java/org/thoughtcrime/securesms/contacts/avatars/LocalFileContactPhoto.java
@@ -55,7 +55,7 @@ public abstract class LocalFileContactPhoto implements ContactPhoto {
 
     @Override
     public boolean equals(Object other) {
-        if (other == null || !(other instanceof LocalFileContactPhoto)) return false;
+        if (!(other instanceof LocalFileContactPhoto)) return false;
 
         LocalFileContactPhoto that = (LocalFileContactPhoto) other;
         return this.address.equals(that.address) && this.id == that.id && this.path.equals(that.path);
diff --git a/src/main/java/org/thoughtcrime/securesms/database/CursorRecyclerViewAdapter.java b/src/main/java/org/thoughtcrime/securesms/database/CursorRecyclerViewAdapter.java
index c75af9e59..e517390ca 100644
--- a/src/main/java/org/thoughtcrime/securesms/database/CursorRecyclerViewAdapter.java
+++ b/src/main/java/org/thoughtcrime/securesms/database/CursorRecyclerViewAdapter.java
@@ -115,7 +115,7 @@ public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHold
 
   @SuppressWarnings("unchecked")
   @Override
-  public final void onViewRecycled(ViewHolder holder) {
+  public final void onViewRecycled(@NonNull ViewHolder holder) {
     if (!(holder instanceof HeaderFooterViewHolder)) {
       onItemViewRecycled((VH)holder);
     }
@@ -123,8 +123,9 @@ public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHold
 
   public void onItemViewRecycled(VH holder) {}
 
+  @NonNull
   @Override
-  public final ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+  public final ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
     switch (viewType) {
     case HEADER_TYPE: return new HeaderFooterViewHolder(header);
     case FOOTER_TYPE: return new HeaderFooterViewHolder(footer);
@@ -136,7 +137,7 @@ public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHold
 
   @SuppressWarnings("unchecked")
   @Override
-  public final void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
+  public final void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int position) {
     if (!isHeaderPosition(position) && !isFooterPosition(position)) {
       if (isFastAccessPosition(position)) onBindFastAccessItemViewHolder((VH)viewHolder, position);
       else                                onBindItemViewHolder((VH)viewHolder, getCursorAtPositionOrThrow(position));
diff --git a/src/main/java/org/thoughtcrime/securesms/database/model/ThreadRecord.java b/src/main/java/org/thoughtcrime/securesms/database/model/ThreadRecord.java
index 2ccbad64b..7bd2a7842 100644
--- a/src/main/java/org/thoughtcrime/securesms/database/model/ThreadRecord.java
+++ b/src/main/java/org/thoughtcrime/securesms/database/model/ThreadRecord.java
@@ -73,7 +73,7 @@ public class ThreadRecord {
   }
 
   public @NonNull String getBody() {
-    return body == null ? "" : body;
+    return body;
   }
 
   public Recipient getRecipient() {
diff --git a/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocation.java b/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocation.java
index 50915a69b..23ce38eb4 100644
--- a/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocation.java
+++ b/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocation.java
@@ -29,7 +29,7 @@ public class DcLocation extends Observable {
 
 
     public boolean isValid() {
-        return !lastLocation.getProvider().equals("?");
+        return !"?".equals(lastLocation.getProvider());
     }
 
     void updateLocation(Location location) {
@@ -47,8 +47,7 @@ public class DcLocation extends Observable {
     }
 
     private Location getDefault() {
-        Location location = new Location("?");
-        return location;
+        return new Location("?");
     }
 
     /** https://developer.android.com/guide/topics/location/strategies
diff --git a/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocationManager.java b/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocationManager.java
index 2baec0d99..1876caa2c 100644
--- a/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocationManager.java
+++ b/src/main/java/org/thoughtcrime/securesms/geolocation/DcLocationManager.java
@@ -28,7 +28,7 @@ public class DcLocationManager implements Observer {
         public void onServiceConnected(ComponentName name, IBinder service) {
             Log.d(TAG, "background service connected");
             serviceBinder = (LocationBackgroundService.LocationBackgroundServiceBinder) service;
-            while (pendingShareLastLocation.size() > 0) {
+            while (!pendingShareLastLocation.isEmpty()) {
                 shareLastLocation(pendingShareLastLocation.pop());
             }
         }
diff --git a/src/main/java/org/thoughtcrime/securesms/geolocation/LocationBackgroundService.java b/src/main/java/org/thoughtcrime/securesms/geolocation/LocationBackgroundService.java
index 05ae2409e..4b17f1d27 100644
--- a/src/main/java/org/thoughtcrime/securesms/geolocation/LocationBackgroundService.java
+++ b/src/main/java/org/thoughtcrime/securesms/geolocation/LocationBackgroundService.java
@@ -12,6 +12,8 @@ import android.os.Bundle;
 import android.os.IBinder;
 import android.util.Log;
 
+import androidx.annotation.NonNull;
+
 public class LocationBackgroundService extends Service {
 
     private static final int INITIAL_TIMEOUT = 1000 * 60 * 2;
@@ -111,7 +113,7 @@ public class LocationBackgroundService extends Service {
     private class ServiceLocationListener implements LocationListener {
 
         @Override
-        public void onLocationChanged(Location location) {
+        public void onLocationChanged(@NonNull Location location) {
             Log.d(TAG, "onLocationChanged: " + location);
             if (location == null) {
                 return;
@@ -120,12 +122,12 @@ public class LocationBackgroundService extends Service {
         }
 
         @Override
-        public void onProviderDisabled(String provider) {
+        public void onProviderDisabled(@NonNull String provider) {
             Log.e(TAG, "onProviderDisabled: " + provider);
         }
 
         @Override
-        public void onProviderEnabled(String provider) {
+        public void onProviderEnabled(@NonNull String provider) {
             Log.e(TAG, "onProviderEnabled: " + provider);
         }
 
diff --git a/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoFetcher.java b/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoFetcher.java
index d7844ce48..56db549e7 100644
--- a/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoFetcher.java
+++ b/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoFetcher.java
@@ -27,7 +27,7 @@ class ContactPhotoFetcher implements DataFetcher<InputStream> {
   }
 
   @Override
-  public void loadData(Priority priority, DataCallback<? super InputStream> callback) {
+  public void loadData(@NonNull Priority priority, DataCallback<? super InputStream> callback) {
     try {
       inputStream = contactPhoto.openInputStream(context);
       callback.onDataReady(inputStream);
@@ -40,7 +40,7 @@ class ContactPhotoFetcher implements DataFetcher<InputStream> {
   public void cleanup() {
     try {
       if (inputStream != null) inputStream.close();
-    } catch (IOException e) {}
+    } catch (IOException ignored) {}
   }
 
   @Override
diff --git a/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoLoader.java b/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoLoader.java
index 0bafbfc1d..cfe867ce4 100644
--- a/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoLoader.java
+++ b/src/main/java/org/thoughtcrime/securesms/glide/ContactPhotoLoader.java
@@ -2,6 +2,7 @@ package org.thoughtcrime.securesms.glide;
 
 import android.content.Context;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.bumptech.glide.load.Options;
@@ -23,12 +24,12 @@ public class ContactPhotoLoader implements ModelLoader<ContactPhoto, InputStream
 
   @Nullable
   @Override
-  public LoadData<InputStream> buildLoadData(ContactPhoto contactPhoto, int width, int height, Options options) {
+  public LoadData<InputStream> buildLoadData(@NonNull ContactPhoto contactPhoto, int width, int height, @NonNull Options options) {
     return new LoadData<>(contactPhoto, new ContactPhotoFetcher(context, contactPhoto));
   }
 
   @Override
-  public boolean handles(ContactPhoto contactPhoto) {
+  public boolean handles(@NonNull ContactPhoto contactPhoto) {
     return true;
   }
 
@@ -40,8 +41,9 @@ public class ContactPhotoLoader implements ModelLoader<ContactPhoto, InputStream
       this.context = context.getApplicationContext();
     }
 
+    @NonNull
     @Override
-    public ModelLoader<ContactPhoto, InputStream> build(MultiModelLoaderFactory multiFactory) {
+    public ModelLoader<ContactPhoto, InputStream> build(@NonNull MultiModelLoaderFactory multiFactory) {
       return new ContactPhotoLoader(context);
     }
 
diff --git a/src/main/java/org/thoughtcrime/securesms/mms/AttachmentManager.java b/src/main/java/org/thoughtcrime/securesms/mms/AttachmentManager.java
index 77bd46add..d00fe7e9a 100644
--- a/src/main/java/org/thoughtcrime/securesms/mms/AttachmentManager.java
+++ b/src/main/java/org/thoughtcrime/securesms/mms/AttachmentManager.java
@@ -273,7 +273,7 @@ public class AttachmentManager {
         if (slide == null) {
           setAttachmentPresent(false);
           result.set(false);
-        } else if (slide.getFileSize()>1*1024*1024*1024) {
+        } else if (slide.getFileSize() > 1024 * 1024 * 1024) {
           // this is only a rough check, videos and images may be recoded
           // and the core checks more carefully later.
           setAttachmentPresent(false);
@@ -333,28 +333,24 @@ public class AttachmentManager {
       }
 
       private @Nullable Slide getContentResolverSlideInfo(Uri uri, int width, int height, int chatId) {
-        Cursor cursor = null;
-        long   start  = System.currentTimeMillis();
 
-        try {
-          cursor = context.getContentResolver().query(uri, null, null, null, null);
+        long   start  = System.currentTimeMillis();
+        try (Cursor cursor = context.getContentResolver().query(uri, null, null, null, null)) {
 
           if (cursor != null && cursor.moveToFirst()) {
             String fileName = cursor.getString(cursor.getColumnIndexOrThrow(OpenableColumns.DISPLAY_NAME));
-            long   fileSize = cursor.getLong(cursor.getColumnIndexOrThrow(OpenableColumns.SIZE));
+            long fileSize = cursor.getLong(cursor.getColumnIndexOrThrow(OpenableColumns.SIZE));
             String mimeType = context.getContentResolver().getType(uri);
 
             if (width == 0 || height == 0) {
               Pair<Integer, Integer> dimens = MediaUtil.getDimensions(context, mimeType, uri);
-              width  = dimens.first;
+              width = dimens.first;
               height = dimens.second;
             }
 
             Log.w(TAG, "remote slide with size " + fileSize + " took " + (System.currentTimeMillis() - start) + "ms");
             return mediaType.createSlide(context, uri, fileName, mimeType, fileSize, width, height, chatId);
           }
-        } finally {
-          if (cursor != null) cursor.close();
         }
 
         return null;
@@ -395,7 +391,7 @@ public class AttachmentManager {
           try {
             fileName = new File(uri.getPath()).getName();
           } catch(Exception e) {
-            Log.w(TAG, "Could not get file name from uri: " + e.toString());
+            Log.w(TAG, "Could not get file name from uri: " + e);
           }
         }
 
@@ -431,14 +427,11 @@ public class AttachmentManager {
 
   public static @Nullable String getFileName(Context context, Uri uri) {
     String result = null;
-    if (uri.getScheme().equals("content")) {
-      Cursor cursor = context.getContentResolver().query(uri, new String[]{OpenableColumns.DISPLAY_NAME}, null, null, null);
-      try {
+    if ("content".equals(uri.getScheme())) {
+      try (Cursor cursor = context.getContentResolver().query(uri, new String[]{OpenableColumns.DISPLAY_NAME}, null, null, null)) {
         if (cursor != null && cursor.moveToFirst()) {
           result = cursor.getString(cursor.getColumnIndexOrThrow(OpenableColumns.DISPLAY_NAME));
         }
-      } finally {
-        if (cursor != null) cursor.close();
       }
     }
     if (result == null) {
@@ -495,11 +488,10 @@ public class AttachmentManager {
             .withPermanentDenialDialog(activity.getString(R.string.perm_explain_access_to_location_denied))
             .onAllGranted(() -> {
               ShareLocationDialog.show(activity, durationInSeconds -> {
-                switch (durationInSeconds) {
-                  case 1: dcLocationManager.shareLastLocation(chatId); break;
-                  default:
-                    dcLocationManager.shareLocation(durationInSeconds, chatId);
-                    break;
+                if (durationInSeconds == 1) {
+                  dcLocationManager.shareLastLocation(chatId);
+                } else {
+                  dcLocationManager.shareLocation(durationInSeconds, chatId);
                 }
               });
             });
@@ -704,7 +696,7 @@ public class AttachmentManager {
               return slide;
             }
           } catch (RpcException e) {
-            e.printStackTrace();
+            Log.e(TAG, "Error in call to rpc.parseVcard()", e);
           }
         }
 
diff --git a/src/main/java/org/thoughtcrime/securesms/mms/AudioSlide.java b/src/main/java/org/thoughtcrime/securesms/mms/AudioSlide.java
index 421c2db62..48a9a904b 100644
--- a/src/main/java/org/thoughtcrime/securesms/mms/AudioSlide.java
+++ b/src/main/java/org/thoughtcrime/securesms/mms/AudioSlide.java
@@ -58,11 +58,6 @@ public class AudioSlide extends Slide {
     return null;
   }
 
-  @Override
-  public boolean hasImage() {
-    return false;
-  }
-
   @Override
   public boolean hasAudio() {
     return true;
diff --git a/src/main/java/org/thoughtcrime/securesms/mms/GifSlide.java b/src/main/java/org/thoughtcrime/securesms/mms/GifSlide.java
index 44620dac8..2811be6e3 100644
--- a/src/main/java/org/thoughtcrime/securesms/mms/GifSlide.java
+++ b/src/main/java/org/thoughtcrime/securesms/mms/GifSlide.java
@@ -3,8 +3,6 @@ package org.thoughtcrime.securesms.mms;
 import android.content.Context;
 import android.net.Uri;
 
-import androidx.annotation.Nullable;
-
 import com.b44t.messenger.DcMsg;
 
 import org.thoughtcrime.securesms.util.MediaUtil;
@@ -19,9 +17,4 @@ public class GifSlide extends ImageSlide {
     super(context, constructAttachmentFromUri(context, uri, MediaUtil.IMAGE_GIF, size, width, height, uri, fileName, false));
   }
 
-  @Override
-  @Nullable
-  public Uri getThumbnailUri() {
-    return getUri();
-  }
 }
diff --git a/src/main/java/org/thoughtcrime/securesms/mms/QuoteModel.java b/src/main/java/org/thoughtcrime/securesms/mms/QuoteModel.java
index 9969f594b..3b6655c61 100644
--- a/src/main/java/org/thoughtcrime/securesms/mms/QuoteModel.java
+++ b/src/main/java/org/thoughtcrime/securesms/mms/QuoteModel.java
@@ -17,7 +17,7 @@ public class QuoteModel {
   private final List<Attachment> attachments;
   private final DcMsg quotedMsg;
 
-  public QuoteModel(DcContact author, String text, boolean missing, @Nullable List<Attachment> attachments, DcMsg quotedMsg) {
+  public QuoteModel(DcContact author, String text, @Nullable List<Attachment> attachments, DcMsg quotedMsg) {
     this.author      = author;
     this.text        = text;
     this.attachments = attachments;
diff --git a/src/main/java/org/thoughtcrime/securesms/mms/SignalGlideModule.java b/src/main/java/org/thoughtcrime/securesms/mms/SignalGlideModule.java
index 01095ad12..862c7c7fd 100644
--- a/src/main/java/org/thoughtcrime/securesms/mms/SignalGlideModule.java
+++ b/src/main/java/org/thoughtcrime/securesms/mms/SignalGlideModule.java
@@ -32,7 +32,7 @@ public class SignalGlideModule extends AppGlideModule {
   }
 
   @Override
-  public void applyOptions(Context context, GlideBuilder builder) {
+  public void applyOptions(@NonNull Context context, GlideBuilder builder) {
     builder.setLogLevel(Log.ERROR);
 //    builder.setDiskCache(new NoopDiskCacheFactory());
   }
diff --git a/src/main/java/org/thoughtcrime/securesms/notifications/InChatSounds.java b/src/main/java/org/thoughtcrime/securesms/notifications/InChatSounds.java
index 6838def9c..373d7bc09 100644
--- a/src/main/java/org/thoughtcrime/securesms/notifications/InChatSounds.java
+++ b/src/main/java/org/thoughtcrime/securesms/notifications/InChatSounds.java
@@ -1,7 +1,7 @@
 package org.thoughtcrime.securesms.notifications;
 
 import android.content.Context;
-import android.media.AudioManager;
+import android.media.AudioAttributes;
 import android.media.SoundPool;
 import android.util.Log;
 
@@ -28,7 +28,11 @@ public class InChatSounds {
 
     private InChatSounds(Context context) {
         try {
-            soundPool = new SoundPool(3, AudioManager.STREAM_SYSTEM, 0);
+            AudioAttributes audioAttrs = new AudioAttributes.Builder()
+              .setUsage(AudioAttributes.USAGE_ASSISTANCE_SONIFICATION)
+              .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
+              .build();
+            soundPool = new SoundPool.Builder().setMaxStreams(3).setAudioAttributes(audioAttrs).build();
             soundIn = soundPool.load(context, R.raw.sound_in, 1);
             soundOut = soundPool.load(context, R.raw.sound_out, 1);
         } catch(Exception e) {
diff --git a/src/main/java/org/thoughtcrime/securesms/notifications/NotificationCenter.java b/src/main/java/org/thoughtcrime/securesms/notifications/NotificationCenter.java
index 7c39fee4f..5e2f07d1d 100644
--- a/src/main/java/org/thoughtcrime/securesms/notifications/NotificationCenter.java
+++ b/src/main/java/org/thoughtcrime/securesms/notifications/NotificationCenter.java
@@ -241,7 +241,7 @@ public class NotificationCenter {
                     return new ChatData(accountId, chatId);
                 }
             }
-        } catch(Exception e) { }
+        } catch(Exception ignored) { }
         return null;
     }
 
@@ -326,7 +326,7 @@ public class NotificationCenter {
                 }
             }
             catch(Exception e) {
-                e.printStackTrace();
+                Log.e(TAG, "Error in getNotificationChannel()", e);
             }
         }
 
@@ -604,7 +604,7 @@ public class NotificationCenter {
                     .setGroup(GRP_MSG + "." + accountId)
                     .setGroupSummary(true)
                     .setSmallIcon(R.drawable.icon_notification)
-                    .setColor(context.getResources().getColor(R.color.delta_primary))
+                    .setColor(context.getResources().getColor(R.color.delta_primary, null))
                     .setCategory(NotificationCompat.CATEGORY_MESSAGE)
                     .setContentTitle("Delta Chat") // content title would only be used on SDK <24
                     .setContentText("New messages") // content text would only be used on SDK <24
@@ -692,7 +692,7 @@ public class NotificationCenter {
         }
     }
 
-  private class ChatData {
+  private static class ChatData {
     public final int accountId;
     public final int chatId;
 
diff --git a/src/main/java/org/thoughtcrime/securesms/permissions/PermissionsRequest.java b/src/main/java/org/thoughtcrime/securesms/permissions/PermissionsRequest.java
index 3c008fc1e..2bc0812fe 100644
--- a/src/main/java/org/thoughtcrime/securesms/permissions/PermissionsRequest.java
+++ b/src/main/java/org/thoughtcrime/securesms/permissions/PermissionsRequest.java
@@ -66,18 +66,18 @@ class PermissionsRequest {
       }
     }
 
-    if (allGrantedListener != null && granted.size() > 0 && (denied.size() == 0 && permanentlyDenied.size() == 0)) {
+    if (allGrantedListener != null && !granted.isEmpty() && (denied.isEmpty() && permanentlyDenied.isEmpty())) {
       allGrantedListener.run();
-    } else if (someGrantedListener != null && granted.size() > 0) {
+    } else if (someGrantedListener != null && !granted.isEmpty()) {
       someGrantedListener.accept(granted);
     }
 
-    if (denied.size() > 0) {
+    if (!denied.isEmpty()) {
       if (anyDeniedListener != null)  anyDeniedListener.run();
       if (someDeniedListener != null) someDeniedListener.accept(denied);
     }
 
-    if (permanentlyDenied.size() > 0) {
+    if (!permanentlyDenied.isEmpty()) {
       if (anyPermanentlyDeniedListener != null)  anyPermanentlyDeniedListener.run();
       if (somePermanentlyDeniedListener != null) somePermanentlyDeniedListener.accept(permanentlyDenied);
     }
diff --git a/src/main/java/org/thoughtcrime/securesms/preferences/AppearancePreferenceFragment.java b/src/main/java/org/thoughtcrime/securesms/preferences/AppearancePreferenceFragment.java
index fe95915d7..e5dc4939c 100644
--- a/src/main/java/org/thoughtcrime/securesms/preferences/AppearancePreferenceFragment.java
+++ b/src/main/java/org/thoughtcrime/securesms/preferences/AppearancePreferenceFragment.java
@@ -4,6 +4,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.preference.ListPreference;
 import androidx.preference.Preference;
@@ -82,9 +83,9 @@ public class AppearancePreferenceFragment extends ListSummaryPreferenceFragment
 
   private class BackgroundClickListener implements Preference.OnPreferenceClickListener {
     @Override
-    public boolean onPreferenceClick(Preference preference) {
+    public boolean onPreferenceClick(@NonNull Preference preference) {
       Intent intent = new Intent(getContext(), ChatBackgroundActivity.class);
-      getActivity().startActivity(intent);
+      requireActivity().startActivity(intent);
       return true;
     }
   }
diff --git a/src/main/java/org/thoughtcrime/securesms/preferences/ChatBackgroundActivity.java b/src/main/java/org/thoughtcrime/securesms/preferences/ChatBackgroundActivity.java
index c02cc58dc..f4b58b581 100644
--- a/src/main/java/org/thoughtcrime/securesms/preferences/ChatBackgroundActivity.java
+++ b/src/main/java/org/thoughtcrime/securesms/preferences/ChatBackgroundActivity.java
@@ -134,11 +134,7 @@ public class ChatBackgroundActivity extends PassphraseRequiredActionBarActivity
                     .get();
             FileOutputStream outStream = new FileOutputStream(destinationPath);
             scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 85, outStream);
-        } catch (InterruptedException e) {
-            e.printStackTrace();
-            Prefs.setBackgroundImagePath(context, accountId, "");
-            showBackgroundSaveError();
-        } catch (ExecutionException e) {
+        } catch (InterruptedException | ExecutionException e) {
             e.printStackTrace();
             Prefs.setBackgroundImagePath(context, accountId, "");
             showBackgroundSaveError();
diff --git a/src/main/java/org/thoughtcrime/securesms/preferences/CorrectedPreferenceFragment.java b/src/main/java/org/thoughtcrime/securesms/preferences/CorrectedPreferenceFragment.java
index e31ee397f..7c8796a71 100644
--- a/src/main/java/org/thoughtcrime/securesms/preferences/CorrectedPreferenceFragment.java
+++ b/src/main/java/org/thoughtcrime/securesms/preferences/CorrectedPreferenceFragment.java
@@ -4,6 +4,7 @@ package org.thoughtcrime.securesms.preferences;
 import android.os.Bundle;
 import android.view.View;
 
+import androidx.annotation.NonNull;
 import androidx.fragment.app.DialogFragment;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceFragmentCompat;
@@ -26,7 +27,7 @@ public abstract class CorrectedPreferenceFragment extends PreferenceFragmentComp
   }
 
   @Override
-  public void onDisplayPreferenceDialog(Preference preference) {
+  public void onDisplayPreferenceDialog(@NonNull Preference preference) {
     DialogFragment dialogFragment = null;
 
     if (preference instanceof CustomDefaultPreference) {
diff --git a/src/main/java/org/thoughtcrime/securesms/preferences/ListSummaryPreferenceFragment.java b/src/main/java/org/thoughtcrime/securesms/preferences/ListSummaryPreferenceFragment.java
index 067c84286..140e4a6bb 100644
--- a/src/main/java/org/thoughtcrime/securesms/preferences/ListSummaryPreferenceFragment.java
+++ b/src/main/java/org/thoughtcrime/securesms/preferences/ListSummaryPreferenceFragment.java
@@ -72,7 +72,7 @@ public abstract class ListSummaryPreferenceFragment extends CorrectedPreferenceF
 
   protected class ListSummaryListener implements Preference.OnPreferenceChangeListener {
     @Override
-    public boolean onPreferenceChange(Preference preference, Object value) {
+    public boolean onPreferenceChange(@NonNull Preference preference, Object value) {
       updateListSummary(preference, value);
       return true;
     }
diff --git a/src/main/java/org/thoughtcrime/securesms/preferences/widgets/ProfilePreference.java b/src/main/java/org/thoughtcrime/securesms/preferences/widgets/ProfilePreference.java
index 8dfef4bdb..34785739e 100644
--- a/src/main/java/org/thoughtcrime/securesms/preferences/widgets/ProfilePreference.java
+++ b/src/main/java/org/thoughtcrime/securesms/preferences/widgets/ProfilePreference.java
@@ -7,6 +7,7 @@ import android.util.AttributeSet;
 import android.widget.ImageView;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceViewHolder;
 
@@ -50,7 +51,7 @@ public class ProfilePreference extends Preference {
   }
 
   @Override
-  public void onBindViewHolder(PreferenceViewHolder viewHolder) {
+  public void onBindViewHolder(@NonNull PreferenceViewHolder viewHolder) {
     super.onBindViewHolder(viewHolder);
     avatarView        = (ImageView)viewHolder.findViewById(R.id.avatar);
     profileNameView   = (TextView)viewHolder.findViewById(R.id.profile_name);