Null safety cleanups.

briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java

@@ -70,6 +70,7 @@ import static android.support.v4.app.NotificationCompat.PRIORITY_LOW;
 import static android.support.v4.app.NotificationCompat.PRIORITY_MIN;
 import static android.support.v4.app.NotificationCompat.VISIBILITY_SECRET;
 import static android.support.v4.content.ContextCompat.getColor;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 import static org.briarproject.bramble.util.StringUtils.toHexString;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
@@ -119,8 +120,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		this.androidExecutor = androidExecutor;
 		this.clock = clock;
 		appContext = app.getApplicationContext();
-		notificationManager = (NotificationManager)
+		notificationManager = (NotificationManager) requireNonNull(
-				appContext.getSystemService(NOTIFICATION_SERVICE);
+				appContext.getSystemService(NOTIFICATION_SERVICE));
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java

@@ -30,6 +30,7 @@ import static android.content.Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
 import static android.os.Build.VERSION.SDK_INT;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PASSWORD;
@@ -177,8 +178,8 @@ public abstract class BriarActivity extends BaseActivity {
 		b.setNegativeButton(R.string.cancel,
 				(dialog, which) -> dialog.dismiss());
 		b.setOnDismissListener(dialog -> {
-			CheckBox checkBox =
+			CheckBox checkBox = requireNonNull(
-					((AlertDialog) dialog).findViewById(R.id.checkbox);
+					((AlertDialog) dialog).findViewById(R.id.checkbox));
 			if (checkBox.isChecked())
 				briarController.doNotAskAgainForDozeWhiteListing();
 		});

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseControllerImpl.java

@@ -221,7 +221,6 @@ abstract class BaseControllerImpl extends DbControllerImpl
 			text = HtmlUtils.clean(blogManager.getPostText(m), ARTICLE);
 			textCache.put(m, text);
 		}
-		//noinspection ConstantConditions
 		return text;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -92,13 +92,11 @@ public class BlogFragment extends BaseFragment
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		Bundle args = requireNonNull(getArguments());
-		byte[] b = args.getByteArray(GROUP_ID);
+		groupId = new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
-		if (b == null) throw new IllegalStateException("No group ID in args");
-		groupId = new GroupId(b);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(requireNonNull(getActivity()), this,
+		adapter = new BlogPostAdapter(requireActivity(), this,
 				getFragmentManager());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
@@ -269,7 +267,7 @@ public class BlogFragment extends BaseFragment
 	}
 
 	private void setToolbarTitle(Author a) {
-		getActivity().setTitle(a.getName());
+		requireActivity().setTitle(a.getName());
 	}
 
 	private void loadSharedContacts() {
@@ -311,7 +309,7 @@ public class BlogFragment extends BaseFragment
 
 	private void setToolbarSubTitle(int total, int online) {
 		ActionBar actionBar =
-				((BriarActivity) getActivity()).getSupportActionBar();
+				((BriarActivity) requireActivity()).getSupportActionBar();
 		if (actionBar != null) {
 			actionBar.setSubtitle(
 					getString(R.string.shared_with, total, online));
@@ -336,9 +334,8 @@ public class BlogFragment extends BaseFragment
 		snackbar.getView().setBackgroundResource(R.color.briar_primary);
 		if (scroll) {
 			View.OnClickListener onClick = v -> list.smoothScrollToPosition(0);
-			snackbar.setActionTextColor(ContextCompat
+			snackbar.setActionTextColor(ContextCompat.getColor(requireContext(),
-					.getColor(getContext(),
+					R.color.briar_button_text_positive));
-							R.color.briar_button_text_positive));
 			snackbar.setAction(R.string.blogs_blog_post_scroll_to, onClick);
 		}
 		snackbar.show();
@@ -347,7 +344,7 @@ public class BlogFragment extends BaseFragment
 	private void showDeleteDialog() {
 		DialogInterface.OnClickListener okListener =
 				(dialog, which) -> deleteBlog();
-		AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(),
+		AlertDialog.Builder builder = new AlertDialog.Builder(requireActivity(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.blogs_remove_blog));
 		builder.setMessage(
@@ -362,7 +359,7 @@ public class BlogFragment extends BaseFragment
 				new UiResultExceptionHandler<Void, DbException>(this) {
 					@Override
 					public void onResultUi(Void result) {
-						Toast.makeText(getActivity(),
+						Toast.makeText(requireActivity(),
 								R.string.blogs_blog_removed, LENGTH_SHORT)
 								.show();
 						finish();

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -35,7 +35,6 @@ import javax.inject.Inject;
 import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.support.design.widget.Snackbar.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
@@ -78,14 +77,14 @@ public class FeedFragment extends BaseFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(R.string.blogs_button);
+		requireActivity().setTitle(R.string.blogs_button);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter =
+		adapter = new BlogPostAdapter(requireActivity(), this,
-				new BlogPostAdapter(getActivity(), this, getFragmentManager());
+				getFragmentManager());
 
-		layoutManager = new LinearLayoutManager(getActivity());
+		layoutManager = new LinearLayoutManager(requireActivity());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
@@ -176,19 +175,19 @@ public class FeedFragment extends BaseFragment implements
 		if (personalBlog == null) return false;
 		switch (item.getItemId()) {
 			case R.id.action_write_blog_post:
-				Intent i1 =
+				Intent i1 = new Intent(requireActivity(),
-						new Intent(getActivity(), WriteBlogPostActivity.class);
+								WriteBlogPostActivity.class);
 				i1.putExtra(GROUP_ID, personalBlog.getId().getBytes());
 				startActivityForResult(i1, REQUEST_WRITE_BLOG_POST);
 				return true;
 			case R.id.action_rss_feeds_import:
-				Intent i2 =
+				Intent i2 = new Intent(requireActivity(),
-						new Intent(getActivity(), RssFeedImportActivity.class);
+						RssFeedImportActivity.class);
 				startActivity(i2);
 				return true;
 			case R.id.action_rss_feeds_manage:
-				Intent i3 =
+				Intent i3 = new Intent(requireActivity(),
-						new Intent(getActivity(), RssFeedManageActivity.class);
+						RssFeedManageActivity.class);
 				i3.putExtra(GROUP_ID, personalBlog.getId().getBytes());
 				startActivity(i3);
 				return true;
@@ -230,10 +229,11 @@ public class FeedFragment extends BaseFragment implements
 
 	@Override
 	public void onAuthorClick(BlogPostItem post) {
+		if (getContext() == null) return;
 		Intent i = new Intent(getContext(), BlogActivity.class);
 		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
 		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		getContext().startActivity(i);
+		requireContext().startActivity(i);
 	}
 
 	@Override
@@ -252,9 +252,8 @@ public class FeedFragment extends BaseFragment implements
 		s.getView().setBackgroundResource(R.color.briar_primary);
 		if (scroll) {
 			OnClickListener onClick = v -> list.smoothScrollToPosition(0);
-			s.setActionTextColor(ContextCompat
+			s.setActionTextColor(ContextCompat.getColor(requireContext(),
-					.getColor(getContext(),
+					R.color.briar_button_text_positive));
-							R.color.briar_button_text_positive));
 			s.setAction(R.string.blogs_blog_post_scroll_to, onClick);
 		}
 		s.show();

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogActivity.java

@@ -2,8 +2,11 @@ package org.briarproject.briar.android.blog;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.view.MenuItem;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
@@ -13,11 +16,13 @@ import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener
 
 import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class ReblogActivity extends BriarActivity implements
 		BaseFragmentListener {
 
 	@Override
-	public void onCreate(Bundle savedInstanceState) {
+	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
 		Intent intent = getIntent();

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -51,7 +51,6 @@ import javax.inject.Inject;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static android.support.v4.view.ViewCompat.getTransitionName;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
@@ -106,13 +105,13 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(R.string.contact_list_button);
+		requireActivity().setTitle(R.string.contact_list_button);
 
 		View contentView = inflater.inflate(R.layout.list, container, false);
 
 		OnContactClickListener<ContactListItem> onContactClickListener =
 				(view, item) -> {
-					Intent i = new Intent(getActivity(),
+					Intent i = new Intent(requireActivity(),
 							ConversationActivity.class);
 					ContactId contactId = item.getContact().getId();
 					i.putExtra(CONTACT_ID, contactId.getInt());
@@ -130,16 +129,17 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 								Pair.create(holder.bulb,
 										getTransitionName(holder.bulb));
 						ActivityOptionsCompat options =
-								makeSceneTransitionAnimation(getActivity(),
+								makeSceneTransitionAnimation(requireActivity(),
 										avatar, bulb);
-						ActivityCompat.startActivity(getActivity(), i,
+						ActivityCompat.startActivity(requireActivity(), i,
 								options.toBundle());
 					} else {
 						// work-around for android bug #224270
 						startActivity(i);
 					}
 				};
-		adapter = new ContactListAdapter(getContext(), onContactClickListener);
+		adapter = new ContactListAdapter(requireContext(),
+				onContactClickListener);
 		list = contentView.findViewById(R.id.list);
 		list.setLayoutManager(new LinearLayoutManager(getContext()));
 		list.setAdapter(adapter);
@@ -161,8 +161,8 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 		// Handle presses on the action bar items
 		switch (item.getItemId()) {
 			case R.id.action_add_contact:
-				Intent intent =
+				Intent intent = new Intent(requireContext(),
-						new Intent(getContext(), ContactExchangeActivity.class);
+						ContactExchangeActivity.class);
 				startActivity(intent);
 				return true;
 			default:

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -69,11 +69,11 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 		View contentView = inflater.inflate(R.layout.list, container, false);
 
 		list = contentView.findViewById(R.id.list);
-		list.setLayoutManager(new LinearLayoutManager(getActivity()));
+		list.setLayoutManager(new LinearLayoutManager(requireActivity()));
 		list.setEmptyImage(R.drawable.ic_empty_state_contact_list);
 		list.setEmptyText(getString(R.string.no_contacts_selector));
 		list.setEmptyAction(getString(R.string.no_contacts_selector_action));
-		adapter = getAdapter(requireNonNull(getContext()), this);
+		adapter = getAdapter(requireContext(), this);
 		list.setAdapter(adapter);
 
 		// restore selected contacts if available

briar-android/src/main/java/org/briarproject/briar/android/conversation/AliasDialogFragment.java

@@ -39,9 +39,8 @@ public class AliasDialogFragment extends AppCompatDialogFragment {
 
 		setStyle(STYLE_NO_TITLE, R.style.BriarDialogTheme);
 
-		BriarActivity a = (BriarActivity) requireNonNull(getActivity());
+		((BriarActivity) requireActivity()).getActivityComponent().inject(this);
-		a.getActivityComponent().inject(this);
+		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
-		viewModel = ViewModelProviders.of(getActivity(), viewModelFactory)
 				.get(ConversationViewModel.class);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -502,7 +502,6 @@ public class ConversationActivity extends BriarActivity
 	 * <p>
 	 * Attention: Call this only after contactName has been initialized.
 	 */
-	@SuppressWarnings("ConstantConditions")
 	private List<ConversationItem> createItems(
 			Collection<ConversationMessageHeader> headers) {
 		List<ConversationItem> items = new ArrayList<>(headers.size());

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageFragment.java

@@ -57,8 +57,7 @@ public class ImageFragment extends Fragment {
 	@Override
 	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
 		super.onActivityCreated(savedInstanceState);
-		BaseActivity a = (BaseActivity) requireNonNull(getActivity());
+		((BaseActivity) requireActivity()).getActivityComponent().inject(this);
-		a.getActivityComponent().inject(this);
 	}
 
 	@Override
@@ -78,8 +77,8 @@ public class ImageFragment extends Fragment {
 		View v = inflater.inflate(R.layout.fragment_image, container,
 				false);
 
-		viewModel = ViewModelProviders.of(requireNonNull(getActivity()),
+		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
-				viewModelFactory).get(ImageViewModel.class);
+				.get(ImageViewModel.class);
 
 		photoView = v.findViewById(R.id.photoView);
 		photoView.setScaleLevels(1, 2, 4);

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListFragment.java

@@ -44,7 +44,6 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.support.design.widget.Snackbar.LENGTH_INDEFINITE;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
@@ -93,24 +92,23 @@ public class ForumListFragment extends BaseEventFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
+		requireActivity().setTitle(R.string.forums_button);
-		requireNonNull(getActivity()).setTitle(R.string.forums_button);
 
 		View contentView =
 				inflater.inflate(R.layout.fragment_forum_list, container,
 						false);
 
-		adapter = new ForumListAdapter(getActivity());
+		adapter = new ForumListAdapter(requireActivity());
 
 		list = contentView.findViewById(R.id.forumList);
-		list.setLayoutManager(new LinearLayoutManager(getActivity()));
+		list.setLayoutManager(new LinearLayoutManager(requireActivity()));
 		list.setAdapter(adapter);
 
 		snackbar = Snackbar.make(list, "", LENGTH_INDEFINITE);
 		snackbar.getView().setBackgroundResource(R.color.briar_primary);
 		snackbar.setAction(R.string.show, this);
-		snackbar.setActionTextColor(ContextCompat
+		snackbar.setActionTextColor(ContextCompat.getColor(requireContext(),
-				.getColor(getActivity(), R.color.briar_button_text_positive));
+						R.color.briar_button_text_positive));
 
 		return contentView;
 	}
@@ -148,8 +146,8 @@ public class ForumListFragment extends BaseEventFragment implements
 		// Handle presses on the action bar items
 		switch (item.getItemId()) {
 			case R.id.action_create_forum:
-				Intent intent =
+				Intent intent = new Intent(requireContext(),
-						new Intent(getContext(), CreateForumActivity.class);
+						CreateForumActivity.class);
 				startActivity(intent);
 				return true;
 			default:
@@ -270,7 +268,7 @@ public class ForumListFragment extends BaseEventFragment implements
 	@Override
 	public void onClick(View view) {
 		// snackbar click
-		Intent i = new Intent(getContext(), ForumInvitationActivity.class);
+		Intent i = new Intent(requireContext(), ForumInvitationActivity.class);
 		startActivity(i);
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/fragment/ScreenFilterDialogFragment.java

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.fragment;
 
 import android.annotation.SuppressLint;
-import android.app.Activity;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
@@ -26,6 +25,8 @@ import java.util.Collection;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static java.util.Objects.requireNonNull;
+
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ScreenFilterDialogFragment extends DialogFragment {
@@ -58,26 +59,20 @@ public class ScreenFilterDialogFragment extends DialogFragment {
 	@Override
 	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
 		super.onActivityCreated(savedInstanceState);
-		Activity activity = getActivity();
+		((BaseActivity) requireActivity()).getActivityComponent().inject(this);
-		if (activity == null) throw new IllegalStateException();
-		((BaseActivity) activity).getActivityComponent().inject(this);
 	}
 
 	@Override
 	public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
-		Activity activity = getActivity();
+		AlertDialog.Builder builder = new AlertDialog.Builder(requireActivity(),
-		if (activity == null) throw new IllegalStateException();
-		AlertDialog.Builder builder = new AlertDialog.Builder(activity,
 				R.style.BriarDialogThemeNoFilter);
 		builder.setTitle(R.string.screen_filter_title);
-		Bundle args = getArguments();
+		Bundle args = requireNonNull(getArguments());
-		if (args == null) throw new IllegalStateException();
+		ArrayList<String> appNames =
-		ArrayList<String> appNames = args.getStringArrayList("appNames");
+				requireNonNull(args.getStringArrayList("appNames"));
 		ArrayList<String> packageNames =
-				args.getStringArrayList("packageNames");
+				requireNonNull(args.getStringArrayList("packageNames"));
-		if (appNames == null || packageNames == null)
+		LayoutInflater inflater = requireActivity().getLayoutInflater();
-			throw new IllegalStateException();
-		LayoutInflater inflater = activity.getLayoutInflater();
 		// See https://stackoverflow.com/a/24720976/6314875
 		@SuppressLint("InflateParams")
 		View dialogView = inflater.inflate(R.layout.dialog_screen_filter, null);

briar-android/src/main/java/org/briarproject/briar/android/introduction/ContactChooserFragment.java

@@ -76,7 +76,6 @@ public class ContactChooserFragment extends BaseFragment {
 	@Override
 	public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
 		View contentView = inflater.inflate(R.layout.list, container, false);
 
 		OnContactClickListener<ContactListItem> onContactClickListener =
@@ -85,11 +84,11 @@ public class ContactChooserFragment extends BaseFragment {
 					Contact c2 = item.getContact();
 					showMessageScreen(c1, c2);
 				};
-		adapter = new ContactListAdapter(requireNonNull(getActivity()),
+		adapter = new ContactListAdapter(requireActivity(),
 				onContactClickListener);
 
 		list = contentView.findViewById(R.id.list);
-		list.setLayoutManager(new LinearLayoutManager(getActivity()));
+		list.setLayoutManager(new LinearLayoutManager(requireActivity()));
 		list.setAdapter(adapter);
 		list.setEmptyText(R.string.no_contacts);
 

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/CameraView.java

@@ -36,6 +36,7 @@ import static android.hardware.Camera.Parameters.FOCUS_MODE_MACRO;
 import static android.hardware.Camera.Parameters.SCENE_MODE_AUTO;
 import static android.hardware.Camera.Parameters.SCENE_MODE_BARCODE;
 import static android.os.Build.VERSION.SDK_INT;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
@@ -127,7 +128,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 		}
 		setDisplayOrientation(getScreenRotationDegrees());
 		// Use barcode scene mode if it's available
-		Parameters params = camera.getParameters();
+		Parameters params = requireNonNull(camera).getParameters();
 		params = setSceneMode(camera, params);
 		if (SCENE_MODE_BARCODE.equals(params.getSceneMode())) {
 			// If the scene mode enabled the flash, try to disable it
@@ -164,8 +165,9 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 	 * See {@link Camera#setDisplayOrientation(int)}.
 	 */
 	private int getScreenRotationDegrees() {
-		WindowManager wm =
+		WindowManager wm = (WindowManager)
-				(WindowManager) getContext().getSystemService(WINDOW_SERVICE);
+				getContext().getSystemService(WINDOW_SERVICE);
+		if (wm == null) return 0;
 		Display d = wm.getDefaultDisplay();
 		switch (d.getRotation()) {
 			case Surface.ROTATION_0:

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeErrorFragment.java

@@ -71,9 +71,7 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 
 		// buttons
 		Button tryAgain = v.findViewById(R.id.tryAgainButton);
-		tryAgain.setOnClickListener(view -> {
+		tryAgain.setOnClickListener(view -> requireActivity().onBackPressed());
-			if (getActivity() != null) getActivity().onBackPressed();
-		});
 		Button cancel = v.findViewById(R.id.cancelButton);
 		cancel.setOnClickListener(view -> finish());
 		return v;

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementActivity.java

@@ -42,6 +42,7 @@ import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE;
 import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
 import static android.bluetooth.BluetoothAdapter.STATE_ON;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_BLUETOOTH_DISCOVERABLE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMISSION_CAMERA_LOCATION;
@@ -96,14 +97,13 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		component.inject(this);
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	@Override
 	public void onCreate(@Nullable Bundle state) {
 		super.onCreate(state);
 		setContentView(R.layout.activity_fragment_container_toolbar);
 		Toolbar toolbar = findViewById(R.id.toolbar);
 		setSupportActionBar(toolbar);
-		getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
 		if (state == null) {
 			showInitialFragment(IntroFragment.newInstance());
 		}
@@ -202,7 +202,8 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	}
 
 	@Override
-	public void onActivityResult(int request, int result, Intent data) {
+	public void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		if (request == REQUEST_BLUETOOTH_DISCOVERABLE) {
 			if (result == RESULT_CANCELED) {
 				setBluetoothState(BluetoothState.REFUSED);

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementFragment.java

@@ -53,7 +53,6 @@ import static android.view.View.VISIBLE;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.widget.LinearLayout.HORIZONTAL;
 import static android.widget.Toast.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
@@ -139,8 +138,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@Override
 	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
 		super.onActivityCreated(savedInstanceState);
-		requireNonNull(getActivity())
+		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
-				.setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
 		cameraView.setPreviewConsumer(new QrCodeDecoder(this));
 	}
 
@@ -191,7 +189,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@UiThread
 	private void logCameraExceptionAndFinish(CameraException e) {
 		logException(LOG, WARNING, e);
-		Toast.makeText(getActivity(), R.string.camera_error,
+		Toast.makeText(requireActivity(), R.string.camera_error,
 				LENGTH_LONG).show();
 		finish();
 	}
@@ -262,7 +260,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 		} catch (IOException | IllegalArgumentException e) {
 			LOG.log(WARNING, "QR Code Invalid", e);
 			reset();
-			Toast.makeText(getActivity(), R.string.qr_code_invalid,
+			Toast.makeText(requireActivity(), R.string.qr_code_invalid,
 					LENGTH_LONG).show();
 		}
 	}
@@ -353,7 +351,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 
 	@Override
 	protected void finish() {
-		getActivity().getSupportFragmentManager().popBackStack();
+		requireActivity().getSupportFragmentManager().popBackStack();
 	}
 
 	@NotNullByDefault

briar-android/src/main/java/org/briarproject/briar/android/login/AuthorNameFragment.java

@@ -17,7 +17,6 @@ import javax.annotation.Nullable;
 
 import static android.view.inputmethod.EditorInfo.IME_ACTION_NEXT;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_NONE;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.util.StringUtils.toUtf8;
 import static org.briarproject.briar.android.util.UiUtils.setError;
@@ -45,7 +44,7 @@ public class AuthorNameFragment extends SetupFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(getString(R.string.setup_title));
+		requireActivity().setTitle(getString(R.string.setup_title));
 		View v = inflater.inflate(R.layout.fragment_setup_author_name,
 				container, false);
 		authorNameWrapper = v.findViewById(R.id.nickname_entry_wrapper);

briar-android/src/main/java/org/briarproject/briar/android/login/DozeFragment.java

@@ -18,7 +18,6 @@ import org.briarproject.briar.android.login.PowerView.OnCheckedChangedListener;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.util.UiUtils.getDozeWhitelistingIntent;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
@@ -49,7 +48,7 @@ public class DozeFragment extends SetupFragment
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(getString(R.string.setup_doze_title));
+		requireActivity().setTitle(getString(R.string.setup_doze_title));
 		setHasOptionsMenu(false);
 		View v = inflater.inflate(R.layout.fragment_setup_doze, container,
 						false);
@@ -100,8 +99,7 @@ public class DozeFragment extends SetupFragment
 
 	@SuppressLint("BatteryLife")
 	private void askForDozeWhitelisting() {
-		if (getContext() == null) return;
+		Intent i = getDozeWhitelistingIntent(requireContext());
-		Intent i = getDozeWhitelistingIntent(getContext());
 		startActivityForResult(i, REQUEST_DOZE_WHITELISTING);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/login/PasswordFragment.java

@@ -22,7 +22,6 @@ import static android.content.Context.INPUT_METHOD_SERVICE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
 import static org.briarproject.briar.android.util.UiUtils.setError;
 
@@ -53,7 +52,7 @@ public class PasswordFragment extends SetupFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(getString(R.string.setup_password_intro));
+		requireActivity().setTitle(getString(R.string.setup_password_intro));
 		View v = inflater.inflate(R.layout.fragment_setup_password, container,
 						false);
 
@@ -115,8 +114,9 @@ public class PasswordFragment extends SetupFragment {
 	@Override
 	public void onClick(View view) {
 		IBinder token = passwordEntry.getWindowToken();
-		Object o = getContext().getSystemService(INPUT_METHOD_SERVICE);
+		InputMethodManager im = (InputMethodManager)
-		((InputMethodManager) o).hideSoftInputFromWindow(token, 0);
+				requireContext().getSystemService(INPUT_METHOD_SERVICE);
+		if (im != null) im.hideSoftInputFromWindow(token, 0);
 		setupController.setPassword(passwordEntry.getText().toString());
 		if (setupController.needToShowDozeFragment()) {
 			setupController.showDozeFragment();

briar-android/src/main/java/org/briarproject/briar/android/login/PowerView.java

@@ -19,6 +19,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
 import static android.content.Context.LAYOUT_INFLATER_SERVICE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
 @UiThread
@@ -42,13 +43,12 @@ abstract class PowerView extends ConstraintLayout {
 		this(context, attrs, 0);
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	public PowerView(Context context, @Nullable AttributeSet attrs,
 			int defStyleAttr) {
 		super(context, attrs, defStyleAttr);
 
-		LayoutInflater inflater = (LayoutInflater) context
+		LayoutInflater inflater = (LayoutInflater) requireNonNull(
-				.getSystemService(LAYOUT_INFLATER_SERVICE);
+				context.getSystemService(LAYOUT_INFLATER_SERVICE));
 		View v = inflater.inflate(R.layout.power_view, this, true);
 
 		textView = v.findViewById(R.id.textView);

briar-android/src/main/java/org/briarproject/briar/android/login/SetupFragment.java

@@ -40,7 +40,7 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		if (item.getItemId() == R.id.action_help) {
-			showOnboardingDialog(getContext(), getHelpText());
+			showOnboardingDialog(requireContext(), getHelpText());
 			return true;
 		} else {
 			return super.onOptionsItemSelected(item);

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -4,7 +4,6 @@ import android.annotation.SuppressLint;
 import android.content.Intent;
 import android.content.res.Configuration;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.design.widget.NavigationView;
 import android.support.design.widget.NavigationView.OnNavigationItemSelectedListener;
@@ -223,7 +222,7 @@ public class NavDrawerActivity extends BriarActivity implements
 	}
 
 	@Override
-	public boolean onNavigationItemSelected(@NonNull MenuItem item) {
+	public boolean onNavigationItemSelected(MenuItem item) {
 		drawerLayout.closeDrawer(START);
 		clearBackStack();
 		if (item.getItemId() == R.id.nav_btn_lock) {
@@ -325,7 +324,6 @@ public class NavDrawerActivity extends BriarActivity implements
 		if (item != null) item.setVisible(visible);
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	private void showExpiryWarning(ExpiryWarning expiry) {
 		int daysUntilExpiry = getDaysUntilExpiry();
 		if (daysUntilExpiry < 0) signOut();

briar-android/src/main/java/org/briarproject/briar/android/panic/PanicPreferencesFragment.java

@@ -53,23 +53,23 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 	}
 
 	private void updatePreferences() {
-		pm = getActivity().getPackageManager();
+		pm = requireActivity().getPackageManager();
 
 		lockPref = (SwitchPreference) findPreference(KEY_LOCK);
 		panicAppPref = (ListPreference) findPreference(KEY_PANIC_APP);
 		purgePref = (SwitchPreference) findPreference(KEY_PURGE);
 
 		// check for connect/disconnect intents from panic trigger apps
-		if (checkForDisconnectIntent(getActivity())) {
+		if (checkForDisconnectIntent(requireActivity())) {
 			LOG.info("Received DISCONNECT intent from Panic Trigger App.");
 			// the necessary action should have been performed by the check
-			getActivity().finish();
+			requireActivity().finish();
 		} else {
 			// check if we got a connect intent from a not yet connected app
-			String packageName = getConnectIntentSender(getActivity());
+			String packageName = getConnectIntentSender(requireActivity());
 			if (!TextUtils.isEmpty((packageName)) &&
 					!TextUtils.equals(packageName,
-							getTriggerPackageName(getActivity()))) {
+							getTriggerPackageName(requireActivity()))) {
 
 				// A new panic trigger app asks us to connect
 				LOG.info("Received CONNECT intent from new Panic Trigger App.");
@@ -97,13 +97,13 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 
 		panicAppPref.setOnPreferenceChangeListener((preference, newValue) -> {
 			String packageName = (String) newValue;
-			setTriggerPackageName(getActivity(), packageName);
+			setTriggerPackageName(requireActivity(), packageName);
 			showPanicApp(packageName);
 
 			if (packageName.equals(PACKAGE_NAME_NONE)) {
 				purgePref.setChecked(false);
 				purgePref.setEnabled(false);
-				getActivity().setResult(RESULT_CANCELED);
+				requireActivity().setResult(RESULT_CANCELED);
 			} else {
 				purgePref.setEnabled(true);
 			}
@@ -117,8 +117,8 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 				intent.setData(Uri.parse(
 						"market://details?id=info.guardianproject.ripple"));
 				intent.addFlags(FLAG_ACTIVITY_NEW_TASK);
-				if (intent.resolveActivity(getActivity().getPackageManager())
+				PackageManager pm = requireActivity().getPackageManager();
-						!= null) {
+				if (intent.resolveActivity(pm) != null) {
 					startActivity(intent);
 				}
 				return true;
@@ -134,7 +134,7 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 		getPreferenceScreen().getSharedPreferences()
 				.registerOnSharedPreferenceChangeListener(this);
 		updatePreferences();
-		showPanicApp(getTriggerPackageName(getActivity()));
+		showPanicApp(getTriggerPackageName(requireActivity()));
 	}
 
 	@Override
@@ -184,7 +184,7 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 				purgePref.setEnabled(true);
 			} catch (PackageManager.NameNotFoundException e) {
 				// revert back to no app, just to be safe
-				setTriggerPackageName(getActivity(), PACKAGE_NAME_NONE);
+				setTriggerPackageName(requireActivity(), PACKAGE_NAME_NONE);
 				showPanicApp(PACKAGE_NAME_NONE);
 			}
 		}
@@ -192,16 +192,16 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 
 	private void showOptInDialog() {
 		DialogInterface.OnClickListener okListener = (dialog, which) -> {
-			setTriggerPackageName(getActivity());
+			setTriggerPackageName(requireActivity());
-			showPanicApp(getTriggerPackageName(getActivity()));
+			showPanicApp(getTriggerPackageName(requireActivity()));
-			getActivity().setResult(RESULT_OK);
+			requireActivity().setResult(RESULT_OK);
 		};
 		DialogInterface.OnClickListener cancelListener = (dialog, which) -> {
-			getActivity().setResult(RESULT_CANCELED);
+			requireActivity().setResult(RESULT_CANCELED);
-			getActivity().finish();
+			requireActivity().finish();
 		};
 
-		AlertDialog.Builder builder = new AlertDialog.Builder(getContext(),
+		AlertDialog.Builder builder = new AlertDialog.Builder(requireContext(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.dialog_title_connect_panic_app));
 
@@ -226,7 +226,7 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 
 	@Nullable
 	private String getCallingPackageName() {
-		ComponentName componentName = getActivity().getCallingActivity();
+		ComponentName componentName = requireActivity().getCallingActivity();
 		String packageName = null;
 		if (componentName != null) {
 			packageName = componentName.getPackageName();

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupControllerImpl.java

@@ -177,7 +177,6 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 						// Continue
 					}
 				}
-				//noinspection ConstantConditions
 				handler.onResult(null);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupFragment.java

@@ -50,9 +50,9 @@ public class CreateGroupFragment extends BaseFragment {
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
 		View v = inflater.inflate(R.layout.fragment_create_group, container,
 				false);
 		nameEntry = v.findViewById(R.id.name);

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/GroupInviteFragment.java

@@ -14,7 +14,6 @@ import org.briarproject.briar.android.contactselection.SelectableContactItem;
 
 import javax.inject.Inject;
 
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @MethodsNotNullByDefault
@@ -42,7 +41,7 @@ public class GroupInviteFragment extends ContactSelectorFragment {
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
-		requireNonNull(getActivity()).setTitle(R.string.groups_invite_members);
+		requireActivity().setTitle(R.string.groups_invite_members);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListFragment.java

@@ -37,7 +37,6 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.support.design.widget.Snackbar.LENGTH_INDEFINITE;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 
 @MethodsNotNullByDefault
@@ -71,12 +70,11 @@ public class GroupListFragment extends BaseFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
+		requireActivity().setTitle(R.string.groups_button);
-		requireNonNull(getActivity()).setTitle(R.string.groups_button);
 
 		View v = inflater.inflate(R.layout.list, container, false);
 
-		adapter = new GroupListAdapter(getActivity(), this);
+		adapter = new GroupListAdapter(requireActivity(), this);
 		list = v.findViewById(R.id.list);
 		list.setEmptyImage(R.drawable.ic_empty_state_group_list);
 		list.setEmptyText(R.string.groups_list_empty);
@@ -87,8 +85,8 @@ public class GroupListFragment extends BaseFragment implements
 		snackbar = Snackbar.make(list, "", LENGTH_INDEFINITE);
 		snackbar.getView().setBackgroundResource(R.color.briar_primary);
 		snackbar.setAction(R.string.show, this);
-		snackbar.setActionTextColor(ContextCompat
+		snackbar.setActionTextColor(ContextCompat.getColor(requireContext(),
-				.getColor(getActivity(), R.color.briar_button_text_positive));
+				R.color.briar_button_text_positive));
 
 		return v;
 	}
@@ -121,7 +119,8 @@ public class GroupListFragment extends BaseFragment implements
 	public boolean onOptionsItemSelected(MenuItem item) {
 		switch (item.getItemId()) {
 			case R.id.action_add_group:
-				Intent i = new Intent(getContext(), CreateGroupActivity.class);
+				Intent i = new Intent(requireContext(),
+						CreateGroupActivity.class);
 				startActivity(i);
 				return true;
 			default:
@@ -239,7 +238,7 @@ public class GroupListFragment extends BaseFragment implements
 	 */
 	@Override
 	public void onClick(View v) {
-		Intent i = new Intent(getContext(), GroupInvitationActivity.class);
+		Intent i = new Intent(requireContext(), GroupInvitationActivity.class);
 		startActivity(i);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/privategroup/reveal/RevealContactsActivity.java

@@ -43,7 +43,6 @@ public class RevealContactsActivity extends ContactSelectorActivity
 	}
 
 	@Override
-	@SuppressWarnings("ConstantConditions")
 	public void onCreate(@Nullable Bundle bundle) {
 		super.onCreate(bundle);
 

briar-android/src/main/java/org/briarproject/briar/android/reporting/DevReportActivity.java

@@ -44,6 +44,7 @@ import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
 import static android.view.inputmethod.InputMethodManager.SHOW_FORCED;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.acra.ACRAConstants.EXTRA_REPORT_FILE;
@@ -130,8 +131,7 @@ public class DevReportActivity extends BaseCrashReportDialog
 		report = findViewById(R.id.report_content);
 		progress = findViewById(R.id.progress_wheel);
 
-		//noinspection ConstantConditions
+		requireNonNull(getDelegate().getSupportActionBar()).setTitle(
-		getDelegate().getSupportActionBar().setTitle(
 				isFeedback() ? R.string.feedback_title :
 						R.string.crash_report_title);
 		userCommentView.setHint(isFeedback() ? R.string.enter_feedback :
@@ -152,8 +152,9 @@ public class DevReportActivity extends BaseCrashReportDialog
 			reviewing = true;
 			reportForm.setVisibility(VISIBLE);
 			requestReport.setVisibility(INVISIBLE);
-			((InputMethodManager) getSystemService(INPUT_METHOD_SERVICE))
+			InputMethodManager im = (InputMethodManager)
-					.showSoftInput(userCommentView, SHOW_FORCED);
+					getSystemService(INPUT_METHOD_SERVICE);
+			if (im != null) im.showSoftInput(userCommentView, SHOW_FORCED);
 		});
 		findViewById(R.id.declineButton).setOnClickListener(v -> closeReport());
 		chevron.setOnClickListener(v -> {

briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java

@@ -67,6 +67,7 @@ import static android.provider.Settings.System.DEFAULT_NOTIFICATION_URI;
 import static android.support.v4.view.ViewCompat.LAYOUT_DIRECTION_LTR;
 import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Arrays.asList;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
@@ -189,21 +190,19 @@ public class SettingsFragment extends PreferenceFragmentCompat
 
 		language.setOnPreferenceChangeListener(this);
 		theme.setOnPreferenceChangeListener((preference, newValue) -> {
-			if (getActivity() != null) {
+			// activate new theme
-				// activate new theme
+			setTheme(requireActivity(), (String) newValue);
-				setTheme(getActivity(), (String) newValue);
+			// bring up parent activity, so it can change its theme as well
-				// bring up parent activity, so it can change its theme as well
+			// upstream bug: https://issuetracker.google.com/issues/38352704
-				// upstream bug: https://issuetracker.google.com/issues/38352704
+			Intent intent = new Intent(requireActivity(),
-				Intent intent =
+					NavDrawerActivity.class);
-						new Intent(getActivity(), NavDrawerActivity.class);
+			intent.setFlags(FLAG_ACTIVITY_CLEAR_TASK | FLAG_ACTIVITY_NEW_TASK);
-				intent.setFlags(
+			startActivity(intent);
-						FLAG_ACTIVITY_CLEAR_TASK | FLAG_ACTIVITY_NEW_TASK);
+			// bring this activity back to the foreground
-				startActivity(intent);
+			intent = new Intent(requireActivity(),
-				// bring this activity back to the foreground
+					requireActivity().getClass());
-				intent = new Intent(getActivity(), getActivity().getClass());
+			startActivity(intent);
-				startActivity(intent);
+			requireActivity().finish();
-				getActivity().finish();
-			}
 			return true;
 		});
 		enableBluetooth.setOnPreferenceChangeListener(this);
@@ -247,7 +246,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 			Bundle savedInstanceState) {
 		View view = super.onCreateView(inflater, container, savedInstanceState);
 		ColorDrawable divider = new ColorDrawable(
-				ContextCompat.getColor(getContext(), R.color.divider));
+				ContextCompat.getColor(requireContext(), R.color.divider));
 		setDivider(divider);
 		return view;
 	}
@@ -487,8 +486,9 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		pref.setWidgetLayoutResource(0);
 		pref.setSummary(summary);
 		pref.setOnPreferenceClickListener(clickedPref -> {
+			String packageName = requireContext().getPackageName();
 			Intent intent = new Intent(ACTION_CHANNEL_NOTIFICATION_SETTINGS)
-					.putExtra(EXTRA_APP_PACKAGE, getContext().getPackageName())
+					.putExtra(EXTRA_APP_PACKAGE, packageName)
 					.putExtra(EXTRA_CHANNEL_ID, channelId);
 			startActivity(intent);
 			return true;
@@ -571,19 +571,18 @@ public class SettingsFragment extends PreferenceFragmentCompat
 
 	private void languageChanged(String newValue) {
 		AlertDialog.Builder builder =
-				new AlertDialog.Builder(getActivity());
+				new AlertDialog.Builder(requireActivity());
 		builder.setTitle(R.string.pref_language_title);
 		builder.setMessage(R.string.pref_language_changed);
-		builder.setPositiveButton(R.string.sign_out_button,
+		builder.setPositiveButton(R.string.sign_out_button, (dialog, i) -> {
-				(dialogInterface, i) -> {
+			language.setValue(newValue);
-					language.setValue(newValue);
+			Intent intent = new Intent(requireContext(),
-					Intent intent = new Intent(getContext(),
+					NavDrawerActivity.class);
-							NavDrawerActivity.class);
+			intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
-					intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
+			intent.putExtra(INTENT_SIGN_OUT, true);
-					intent.putExtra(INTENT_SIGN_OUT, true);
+			requireActivity().startActivity(intent);
-					getActivity().startActivity(intent);
+			requireActivity().finish();
-					getActivity().finish();
+		});
-				});
 		builder.setNegativeButton(R.string.cancel, null);
 		builder.setCancelable(false);
 		builder.show();
@@ -634,7 +633,8 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_RINGTONE && result == RESULT_OK) {
 			Settings s = new Settings();
-			Uri uri = data.getParcelableExtra(EXTRA_RINGTONE_PICKED_URI);
+			Uri uri = requireNonNull(data).getParcelableExtra(
+					EXTRA_RINGTONE_PICKED_URI);
 			if (uri == null) {
 				// The user chose silence
 				s.putBoolean(PREF_NOTIFY_SOUND, false);
@@ -647,12 +647,12 @@ public class SettingsFragment extends PreferenceFragmentCompat
 				s.put(PREF_NOTIFY_RINGTONE_URI, "");
 			} else {
 				// The user chose a ringtone other than the default
-				Ringtone r = RingtoneManager.getRingtone(getContext(), uri);
+				Ringtone r = RingtoneManager.getRingtone(requireContext(), uri);
 				if (r == null) {
-					Toast.makeText(getContext(), R.string.cannot_load_ringtone,
+					Toast.makeText(requireContext(),
-							LENGTH_SHORT).show();
+							R.string.cannot_load_ringtone, LENGTH_SHORT).show();
 				} else {
-					String name = r.getTitle(getContext());
+					String name = r.getTitle(requireContext());
 					s.putBoolean(PREF_NOTIFY_SOUND, true);
 					s.put(PREF_NOTIFY_RINGTONE_NAME, name);
 					s.put(PREF_NOTIFY_RINGTONE_URI, uri.toString());

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListActivity.java

@@ -77,7 +77,6 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 
 	@CallSuper
 	@Override
-	@SuppressWarnings("ConstantConditions")
 	public void onCreate(@Nullable Bundle state) {
 		super.onCreate(state);
 

briar-android/src/main/java/org/briarproject/briar/android/view/EmojiTextInputView.java

@@ -218,17 +218,17 @@ public class EmojiTextInputView extends KeyboardAwareLinearLayout implements
 	}
 
 	void showSoftKeyboard() {
-		Object o = getContext().getSystemService(INPUT_METHOD_SERVICE);
+		InputMethodManager imm = (InputMethodManager)
-		InputMethodManager imm = (InputMethodManager) requireNonNull(o);
+				getContext().getSystemService(INPUT_METHOD_SERVICE);
-		imm.showSoftInput(editText, SHOW_IMPLICIT);
+		if (imm != null) imm.showSoftInput(editText, SHOW_IMPLICIT);
 	}
 
 	void hideSoftKeyboard() {
 		if (emojiPopup.isShowing()) emojiPopup.dismiss();
 		IBinder token = editText.getWindowToken();
-		Object o = getContext().getSystemService(INPUT_METHOD_SERVICE);
+		InputMethodManager imm = (InputMethodManager)
-		InputMethodManager imm = (InputMethodManager) requireNonNull(o);
+				getContext().getSystemService(INPUT_METHOD_SERVICE);
-		imm.hideSoftInputFromWindow(token, 0);
+		if (imm != null) imm.hideSoftInputFromWindow(token, 0);
 	}
 
 	interface TextInputListener {

briar-android/src/main/java/org/briarproject/briar/android/view/QrCodeView.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.android.view;
 
 import android.content.Context;
 import android.graphics.Bitmap;
-import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 import android.util.AttributeSet;
@@ -11,52 +10,58 @@ import android.view.animation.AlphaAnimation;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
+import static android.content.Context.LAYOUT_INFLATER_SERVICE;
+import static java.util.Objects.requireNonNull;
+
+@NotNullByDefault
 public class QrCodeView extends FrameLayout {
 
-    private final ImageView qrCodeImageView;
+	private final ImageView qrCodeImageView;
-    private boolean fullscreen = false;
+	private boolean fullscreen = false;
-    private FullscreenListener listener;
+	@Nullable
+	private FullscreenListener listener;
 
-    public QrCodeView(@NonNull Context context, @Nullable AttributeSet attrs) {
+	public QrCodeView(Context context, @Nullable AttributeSet attrs) {
-        super(context, attrs);
+		super(context, attrs);
-        LayoutInflater inflater = (LayoutInflater) context
+		LayoutInflater inflater = (LayoutInflater) requireNonNull(
-                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
+				context.getSystemService(LAYOUT_INFLATER_SERVICE));
-        inflater.inflate(R.layout.qr_code_view, this, true);
+		inflater.inflate(R.layout.qr_code_view, this, true);
-        qrCodeImageView = findViewById(R.id.qr_code);
+		qrCodeImageView = findViewById(R.id.qr_code);
-        ImageView fullscreenButton = findViewById(R.id.fullscreen_button);
+		ImageView fullscreenButton = findViewById(R.id.fullscreen_button);
-        fullscreenButton.setOnClickListener(v -> {
+		fullscreenButton.setOnClickListener(v -> {
-                    fullscreen = !fullscreen;
+					fullscreen = !fullscreen;
-                    if (!fullscreen) {
+					if (!fullscreen) {
-                        fullscreenButton.setImageResource(
+						fullscreenButton.setImageResource(
-                                R.drawable.ic_fullscreen_black_48dp);
+								R.drawable.ic_fullscreen_black_48dp);
-                    } else {
+					} else {
-                        fullscreenButton.setImageResource(
+						fullscreenButton.setImageResource(
-                                R.drawable.ic_fullscreen_exit_black_48dp);
+								R.drawable.ic_fullscreen_exit_black_48dp);
-                    }
+					}
-                    if (listener != null)
+					if (listener != null)
-                        listener.setFullscreen(fullscreen);
+						listener.setFullscreen(fullscreen);
-                }
+				}
-        );
+		);
-    }
+	}
 
-    @UiThread
+	@UiThread
-    public void setQrCode(Bitmap qrCode) {
+	public void setQrCode(Bitmap qrCode) {
-        qrCodeImageView.setImageBitmap(qrCode);
+		qrCodeImageView.setImageBitmap(qrCode);
-        // Simple fade-in animation
+		// Simple fade-in animation
-        AlphaAnimation anim = new AlphaAnimation(0.0f, 1.0f);
+		AlphaAnimation anim = new AlphaAnimation(0.0f, 1.0f);
-        anim.setDuration(200);
+		anim.setDuration(200);
-        qrCodeImageView.startAnimation(anim);
+		qrCodeImageView.startAnimation(anim);
-    }
+	}
 
-    @UiThread
+	@UiThread
-    public void setFullscreenListener(FullscreenListener listener) {
+	public void setFullscreenListener(FullscreenListener listener) {
-        this.listener = listener;
+		this.listener = listener;
-    }
+	}
 
-    public interface FullscreenListener {
+	public interface FullscreenListener {
-        void setFullscreen(boolean fullscreen);
+		void setFullscreen(boolean fullscreen);
-    }
+	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/view/TextAvatarView.java

@@ -18,6 +18,9 @@ import javax.annotation.Nullable;
 
 import de.hdodenhof.circleimageview.CircleImageView;
 
+import static android.content.Context.LAYOUT_INFLATER_SERVICE;
+import static java.util.Objects.requireNonNull;
+
 @UiThread
 public class TextAvatarView extends FrameLayout {
 
@@ -28,8 +31,8 @@ public class TextAvatarView extends FrameLayout {
 	public TextAvatarView(Context context, @Nullable AttributeSet attrs) {
 		super(context, attrs);
 
-		LayoutInflater inflater = (LayoutInflater) context
+		LayoutInflater inflater = (LayoutInflater) requireNonNull(
-				.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
+				context.getSystemService(LAYOUT_INFLATER_SERVICE));
 		inflater.inflate(R.layout.text_avatar_view, this, true);
 		character = findViewById(R.id.textAvatarView);
 		background = findViewById(R.id.avatarBackground);

briar-android/src/main/java/org/briarproject/briar/android/view/UnreadMessageButton.java

@@ -16,6 +16,9 @@ import java.util.Locale;
 
 import javax.annotation.Nullable;
 
+import static android.content.Context.LAYOUT_INFLATER_SERVICE;
+import static java.util.Objects.requireNonNull;
+
 @UiThread
 @NotNullByDefault
 public class UnreadMessageButton extends FrameLayout {
@@ -37,8 +40,8 @@ public class UnreadMessageButton extends FrameLayout {
 			int defStyleAttr) {
 		super(context, attrs, defStyleAttr);
 
-		LayoutInflater inflater = (LayoutInflater) context
+		LayoutInflater inflater = (LayoutInflater) requireNonNull(
-				.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
+				context.getSystemService(LAYOUT_INFLATER_SERVICE));
 		inflater.inflate(R.layout.unread_message_button, this, true);
 
 		fab = findViewById(R.id.fab);

briar-android/src/main/java/org/briarproject/briar/android/widget/LinkDialogFragment.java

@@ -5,7 +5,7 @@ import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.net.Uri;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.support.v4.app.DialogFragment;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -13,13 +13,18 @@ import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.TextView;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 
 import java.util.List;
 
 import static android.content.Intent.ACTION_VIEW;
 import static android.content.pm.PackageManager.MATCH_DEFAULT_ONLY;
+import static java.util.Objects.requireNonNull;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class LinkDialogFragment extends DialogFragment {
 
 	private static final String TAG = LinkDialogFragment.class.getName();
@@ -37,18 +42,18 @@ public class LinkDialogFragment extends DialogFragment {
 	}
 
 	@Override
-	public void onCreate(Bundle savedInstanceState) {
+	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
-		url = getArguments().getString("url");
+		url = requireNonNull(getArguments()).getString("url");
 
 		setStyle(STYLE_NO_TITLE, R.style.BriarDialogTheme);
 	}
 
 	@Override
-	public View onCreateView(@NonNull LayoutInflater inflater,
+	public View onCreateView(LayoutInflater inflater,
-			ViewGroup container, Bundle savedInstanceState) {
+			@Nullable ViewGroup container,
-
+			@Nullable Bundle savedInstanceState) {
 		View v = inflater.inflate(R.layout.fragment_link_dialog, container,
 				false);
 
@@ -57,7 +62,7 @@ public class LinkDialogFragment extends DialogFragment {
 
 		// prepare normal intent or intent chooser
 		Intent i = new Intent(ACTION_VIEW, Uri.parse(url));
-		PackageManager pm = getContext().getPackageManager();
+		PackageManager pm = requireContext().getPackageManager();
 		List activities = pm.queryIntentActivities(i, MATCH_DEFAULT_ONLY);
 		boolean choice = activities.size() > 1;
 		Intent intent = choice ? Intent.createChooser(i,

briar-core/src/main/java/org/briarproject/briar/introduction/IntroduceeProtocolEngine.java

@@ -42,6 +42,7 @@ import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.introduction.IntroduceeState.AWAIT_AUTH;
 import static org.briarproject.briar.introduction.IntroduceeState.AWAIT_RESPONSES;
@@ -453,15 +454,13 @@ class IntroduceeProtocolEngine
 							localAuthor.getId());
 
 			// add the keys to the new contact
-			//noinspection ConstantConditions
+			keys = keyManager.addContact(txn, c.getId(),
-			keys = keyManager
+					new SecretKey(requireNonNull(s.getMasterKey())),
-					.addContact(txn, c.getId(), new SecretKey(s.getMasterKey()),
+					timestamp, s.getLocal().alice, false);
-							timestamp, s.getLocal().alice, false);
 
 			// add signed transport properties for the contact
-			//noinspection ConstantConditions
 			transportPropertyManager.addRemoteProperties(txn, c.getId(),
-					s.getRemote().transportProperties);
+					requireNonNull(s.getRemote().transportProperties));
 
 			// Broadcast IntroductionSucceededEvent, because contact got added
 			IntroductionSucceededEvent e = new IntroductionSucceededEvent(c);

briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionCryptoImpl.java

@@ -21,6 +21,7 @@ import java.security.GeneralSecurityException;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.briar.api.introduction.IntroductionConstants.LABEL_ACTIVATE_MAC;
 import static org.briarproject.briar.api.introduction.IntroductionConstants.LABEL_ALICE_MAC_KEY;
 import static org.briarproject.briar.api.introduction.IntroductionConstants.LABEL_AUTH_MAC;
@@ -71,13 +72,12 @@ class IntroductionCryptoImpl implements IntroductionCrypto {
 	}
 
 	@Override
-	@SuppressWarnings("ConstantConditions")
 	public SecretKey deriveMasterKey(IntroduceeSession s)
 			throws GeneralSecurityException {
 		return deriveMasterKey(
-				s.getLocal().ephemeralPublicKey,
+				requireNonNull(s.getLocal().ephemeralPublicKey),
-				s.getLocal().ephemeralPrivateKey,
+				requireNonNull(s.getLocal().ephemeralPrivateKey),
-				s.getRemote().ephemeralPublicKey,
+				requireNonNull(s.getRemote().ephemeralPublicKey),
 				s.getLocal().alice
 		);
 	}
@@ -109,7 +109,6 @@ class IntroductionCryptoImpl implements IntroductionCrypto {
 	}
 
 	@Override
-	@SuppressWarnings("ConstantConditions")
 	public byte[] authMac(SecretKey macKey, IntroduceeSession s,
 			AuthorId localAuthorId) {
 		// the macKey is not yet available in the session at this point
@@ -129,10 +128,9 @@ class IntroductionCryptoImpl implements IntroductionCrypto {
 	}
 
 	@Override
-	@SuppressWarnings("ConstantConditions")
 	public void verifyAuthMac(byte[] mac, IntroduceeSession s,
 			AuthorId localAuthorId) throws GeneralSecurityException {
-		verifyAuthMac(mac, new SecretKey(s.getRemote().macKey),
+		verifyAuthMac(mac, new SecretKey(requireNonNull(s.getRemote().macKey)),
 				s.getIntroducer().getId(), localAuthorId, s.getLocal(),
 				s.getRemote().author.getId(), s.getRemote());
 	}
@@ -148,7 +146,6 @@ class IntroductionCryptoImpl implements IntroductionCrypto {
 		}
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	private byte[] getAuthMacInputs(AuthorId introducerId,
 			AuthorId localAuthorId, Common local, AuthorId remoteAuthorId,
 			Common remote) {
@@ -156,13 +153,15 @@ class IntroductionCryptoImpl implements IntroductionCrypto {
 				localAuthorId,
 				local.acceptTimestamp,
 				local.ephemeralPublicKey,
-				clientHelper.toDictionary(local.transportProperties)
+				clientHelper.toDictionary(requireNonNull(
+						local.transportProperties))
 		);
 		BdfList remoteInfo = BdfList.of(
 				remoteAuthorId,
 				remote.acceptTimestamp,
 				remote.ephemeralPublicKey,
-				clientHelper.toDictionary(remote.transportProperties)
+				clientHelper.toDictionary(requireNonNull(
+						remote.transportProperties))
 		);
 		BdfList macList = BdfList.of(
 				introducerId,
@@ -187,10 +186,9 @@ class IntroductionCryptoImpl implements IntroductionCrypto {
 	}
 
 	@Override
-	@SuppressWarnings("ConstantConditions")
 	public void verifySignature(byte[] signature, IntroduceeSession s)
 			throws GeneralSecurityException {
-		SecretKey macKey = new SecretKey(s.getRemote().macKey);
+		SecretKey macKey = new SecretKey(requireNonNull(s.getRemote().macKey));
 		verifySignature(macKey, s.getRemote().author.getPublicKey(), signature);
 	}
 

briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java

@@ -1309,13 +1309,10 @@ public class IntroductionIntegrationTest
 		Message m = ch.getMessage(id);
 		BdfList body = ch.getMessageAsList(id);
 		if (type == ACCEPT) {
-			//noinspection ConstantConditions
 			return c0.getMessageParser().parseAcceptMessage(m, body);
 		} else if (type == DECLINE) {
-			//noinspection ConstantConditions
 			return c0.getMessageParser().parseDeclineMessage(m, body);
 		} else if (type == AUTH) {
-			//noinspection ConstantConditions
 			return c0.getMessageParser().parseAuthMessage(m, body);
 		} else throw new AssertionError("Not implemented");
 	}

briar-core/src/test/java/org/briarproject/briar/privategroup/PrivateGroupManagerIntegrationTest.java

@@ -120,7 +120,6 @@ public class PrivateGroupManagerIntegrationTest
 		addGroup();
 
 		// create and add test message with no previousMsgId
-		@SuppressWarnings("ConstantConditions")
 		GroupMessage msg = groupMessageFactory
 				.createGroupMessage(groupId0, clock.currentTimeMillis(), null,
 						author0, "test", null);