Add support annotations

build.gradle

@@ -122,6 +122,7 @@ dependencies {
     compile 'com.android.support:multidex:1.0.1'
     compile 'com.nononsenseapps:filepicker:2.5.2'
     compile "com.android.support:design:${SUPPORT_VERSION}"
+    compile "com.android.support:support-annotations:${SUPPORT_VERSION}"
     compile 'com.jakewharton.timber:timber:4.1.2'
     compile 'com.google.guava:guava:19.0'
     compile 'com.jakewharton:process-phoenix:1.0.2'

src/googleplay/java/com/todoroo/astrid/gtasks/GtasksPreferences.java

@@ -9,6 +9,7 @@ import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.preference.CheckBoxPreference;
+import android.support.annotation.NonNull;
 
 import com.todoroo.andlib.utility.DateUtilities;
 import com.todoroo.astrid.dao.MetadataDao;
@@ -118,7 +119,7 @@ public class GtasksPreferences extends InjectingPreferenceActivity implements Go
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_ACCOUNTS) {
             if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 requestLogin();

src/googleplay/java/org/tasks/activities/SupportGoogleTaskListPicker.java

@@ -3,6 +3,7 @@ package org.tasks.activities;
 import android.app.Activity;
 import android.app.Dialog;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.v7.app.AlertDialog;
 
 import com.todoroo.astrid.gtasks.GtasksList;
@@ -26,6 +27,7 @@ public class SupportGoogleTaskListPicker extends InjectingDialogFragment {
 
     private GoogleTaskListSelectionHandler handler;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         return createDialog(dialogBuilder, gtasksListService, list -> handler.selectedList(list));

src/main/java/com/todoroo/astrid/activity/BeastModePreferences.java

@@ -8,6 +8,7 @@ package com.todoroo.astrid.activity;
 import android.content.Context;
 import android.content.res.Resources;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.v4.content.ContextCompat;
 import android.support.v7.widget.Toolbar;
 import android.view.MenuItem;
@@ -70,8 +71,9 @@ public class BeastModePreferences extends ThemedInjectingAppCompatActivity imple
         items = constructOrderedControlList(preferences, this);
 
         adapter = new ArrayAdapter<String>(this, R.layout.preference_draggable_row, R.id.text, items) {
+            @NonNull
             @Override
-            public View getView(int position, View convertView, ViewGroup parent) {
+            public View getView(int position, View convertView, @NonNull ViewGroup parent) {
                 View v = super.getView(position, convertView, parent);
                 TextView display = (TextView) v.findViewById(R.id.text);
                 display.setText(prefsToDescriptions.get(getItem(position)));

src/main/java/com/todoroo/astrid/adapter/FilterAdapter.java

@@ -10,6 +10,7 @@ import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
+import android.support.annotation.NonNull;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -135,8 +136,9 @@ public class FilterAdapter extends ArrayAdapter<FilterListItem> {
         public View view;
     }
 
+    @NonNull
     @Override
-    public View getView(int position, View convertView, ViewGroup parent) {
+    public View getView(int position, View convertView, @NonNull ViewGroup parent) {
         FilterListItem item = getItem(position);
 
         convertView = newView(convertView, parent, item.getItemType());
@@ -180,7 +182,7 @@ public class FilterAdapter extends ArrayAdapter<FilterListItem> {
     }
 
     @Override
-    public View getDropDownView(int position, View convertView, ViewGroup parent) {
+    public View getDropDownView(int position, View convertView, @NonNull ViewGroup parent) {
         return getView(position, convertView, parent);
     }
     /* ======================================================================

src/main/java/com/todoroo/astrid/core/CustomFilterAdapter.java

@@ -6,6 +6,7 @@
 package com.todoroo.astrid.core;
 
 import android.content.DialogInterface;
+import android.support.annotation.NonNull;
 import android.view.ContextMenu;
 import android.view.LayoutInflater;
 import android.view.MenuItem;
@@ -141,8 +142,9 @@ class CustomFilterAdapter extends ArrayAdapter<CriterionInstance> {
 
     // --- view construction
 
+    @NonNull
     @Override
-    public View getView(int position, View convertView, ViewGroup parent) {
+    public View getView(int position, View convertView, @NonNull ViewGroup parent) {
         if(convertView == null) {
             convertView = inflater.inflate(R.layout.custom_filter_row, parent, false);
             ViewHolder viewHolder = new ViewHolder();

src/main/java/com/todoroo/astrid/core/DefaultsPreferences.java

@@ -9,6 +9,7 @@ import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.preference.Preference;
+import android.support.annotation.NonNull;
 
 import org.tasks.R;
 import org.tasks.activities.CalendarSelectionActivity;
@@ -67,7 +68,7 @@ public class DefaultsPreferences extends InjectingPreferenceActivity {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_CALENDAR) {
             if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 startCalendarSelectionActivity();

src/main/java/com/todoroo/astrid/files/AACRecordingActivity.java

@@ -8,6 +8,7 @@ package com.todoroo.astrid.files;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.widget.Chronometer;
 
 import com.todoroo.astrid.voice.AACRecorder;
@@ -99,7 +100,7 @@ public class AACRecordingActivity extends InjectingAppCompatActivity implements
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_MIC) {
             if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 startRecording();

src/main/java/com/todoroo/astrid/provider/Astrid2TaskProvider.java

@@ -11,6 +11,7 @@ import android.content.UriMatcher;
 import android.database.Cursor;
 import android.database.MatrixCursor;
 import android.net.Uri;
+import android.support.annotation.NonNull;
 
 import com.google.common.base.Joiner;
 import com.todoroo.andlib.data.TodorooCursor;
@@ -91,17 +92,17 @@ public class Astrid2TaskProvider extends InjectingContentProvider {
 	}
 
 	@Override
-	public int delete(Uri uri, String selection, String[] selectionArgs) {
+	public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
 		return 0;
 	}
 
 	@Override
-	public String getType(Uri uri) {
+	public String getType(@NonNull Uri uri) {
 		return null;
 	}
 
 	@Override
-	public Uri insert(Uri uri, ContentValues values) {
+	public Uri insert(@NonNull Uri uri, ContentValues values) {
 		return null;
 	}
 
@@ -202,7 +203,7 @@ public class Astrid2TaskProvider extends InjectingContentProvider {
 	}
 
 	@Override
-	public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
+	public Cursor query(@NonNull Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
 		Cursor cursor;
 		switch (URI_MATCHER.match(uri)) {
 
@@ -222,7 +223,7 @@ public class Astrid2TaskProvider extends InjectingContentProvider {
 	}
 
 	@Override
-	public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
+	public int update(@NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
       switch (URI_MATCHER.match(uri)) {
 
         case URI_TASKS:

src/main/java/com/todoroo/astrid/provider/Astrid3ContentProvider.java

@@ -15,6 +15,7 @@ import android.database.Cursor;
 import android.database.SQLException;
 import android.database.sqlite.SQLiteQueryBuilder;
 import android.net.Uri;
+import android.support.annotation.NonNull;
 import android.text.TextUtils;
 
 import com.todoroo.andlib.data.AbstractModel;
@@ -109,7 +110,7 @@ public class Astrid3ContentProvider extends InjectingContentProvider {
     }
 
     @Override
-    public String getType(Uri uri) {
+    public String getType(@NonNull Uri uri) {
         switch (uriMatcher.match(uri)) {
         case URI_DIR:
         case URI_GROUP:
@@ -201,7 +202,7 @@ public class Astrid3ContentProvider extends InjectingContentProvider {
      * @return number of rows deleted
      */
     @Override
-    public int delete(Uri uri, String selection, String[] selectionArgs) {
+    public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
         UriHelper<?> helper = generateHelper(uri, false);
         switch (uriMatcher.match(uri)) {
 
@@ -242,7 +243,7 @@ public class Astrid3ContentProvider extends InjectingContentProvider {
      * Insert key/value pairs into given table
      */
     @Override
-    public Uri insert(Uri uri, ContentValues values) {
+    public Uri insert(@NonNull Uri uri, ContentValues values) {
         UriHelper<?> helper = generateHelper(uri, true);
         switch (uriMatcher.match(uri)) {
 
@@ -277,8 +278,8 @@ public class Astrid3ContentProvider extends InjectingContentProvider {
      * ====================================================================== */
 
     @Override
-    public int update(Uri uri, ContentValues values, String selection,
+    public int update(@NonNull Uri uri, ContentValues values, String selection,
-            String[] selectionArgs) {
+                      String[] selectionArgs) {
         UriHelper<?> helper = generateHelper(uri, true);
 
         switch (uriMatcher.match(uri)) {
@@ -361,8 +362,8 @@ public class Astrid3ContentProvider extends InjectingContentProvider {
      * name of a column
      */
     @Override
-    public Cursor query(Uri uri, String[] projection, String selection,
+    public Cursor query(@NonNull Uri uri, String[] projection, String selection,
-            String[] selectionArgs, String sortOrder) {
+                        String[] selectionArgs, String sortOrder) {
 
         String groupBy = null;
 

src/main/java/com/todoroo/astrid/provider/SqlContentProvider.java

@@ -9,6 +9,7 @@ import android.content.ContentValues;
 import android.content.UriMatcher;
 import android.database.Cursor;
 import android.net.Uri;
+import android.support.annotation.NonNull;
 
 import com.todoroo.astrid.api.AstridApiConstants;
 import com.todoroo.astrid.dao.Database;
@@ -53,7 +54,7 @@ public class SqlContentProvider extends InjectingContentProvider {
     }
 
     @Override
-    public String getType(Uri uri) {
+    public String getType(@NonNull Uri uri) {
         switch (uriMatcher.match(uri)) {
         case 0:
             return "vnd.android.cursor.dir/vnd.astrid";
@@ -71,7 +72,7 @@ public class SqlContentProvider extends InjectingContentProvider {
      * @return number of rows deleted
      */
     @Override
-    public int delete(Uri uri, String selection, String[] selectionArgs) {
+    public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
         throw new UnsupportedOperationException("unimplemented");
     }
 
@@ -83,7 +84,7 @@ public class SqlContentProvider extends InjectingContentProvider {
      * Insert key/value pairs into given table
      */
     @Override
-    public Uri insert(Uri uri, ContentValues values) {
+    public Uri insert(@NonNull Uri uri, ContentValues values) {
         throw new UnsupportedOperationException("unimplemented");
     }
 
@@ -92,7 +93,7 @@ public class SqlContentProvider extends InjectingContentProvider {
      * ====================================================================== */
 
     @Override
-    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
+    public int update(@NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
         throw new UnsupportedOperationException("unimplemented");
     }
 
@@ -108,8 +109,8 @@ public class SqlContentProvider extends InjectingContentProvider {
      * name of a column
      */
     @Override
-    public Cursor query(Uri uri, String[] projection, String selection,
+    public Cursor query(@NonNull Uri uri, String[] projection, String selection,
-            String[] selectionArgs, String sortOrder) {
+                        String[] selectionArgs, String sortOrder) {
 
         return getDatabase().rawQuery(selection);
     }

src/main/java/com/todoroo/astrid/reminders/ReminderPreferences.java

@@ -14,6 +14,7 @@ import android.os.Bundle;
 import android.preference.CheckBoxPreference;
 import android.preference.Preference;
 import android.preference.PreferenceManager;
+import android.support.annotation.NonNull;
 
 import org.tasks.R;
 import org.tasks.activities.ColorPickerActivity;
@@ -113,7 +114,7 @@ public class ReminderPreferences extends InjectingPreferenceActivity {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_CONTACTS) {
             for (int grantResult : grantResults) {
                 if (grantResult != PackageManager.PERMISSION_GRANTED) {

src/main/java/com/todoroo/astrid/tags/TagsControlSet.java

@@ -8,6 +8,7 @@ package com.todoroo.astrid.tags;
 import android.annotation.SuppressLint;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.content.ContextCompat;
 import android.support.v4.graphics.drawable.DrawableCompat;
@@ -153,9 +154,10 @@ public final class TagsControlSet extends TaskEditControlFragment {
         newTagLayout = (LinearLayout) dialogView.findViewById(R.id.newTags);
         tagListView = (ListView) dialogView.findViewById(R.id.existingTags);
         tagListView.setAdapter(new ArrayAdapter<TagData>(getActivity(), R.layout.simple_list_item_multiple_choice_themed, allTags) {
+            @NonNull
             @SuppressLint("NewApi")
             @Override
-            public View getView(int position, View convertView, ViewGroup parent) {
+            public View getView(int position, View convertView, @NonNull ViewGroup parent) {
                 CheckedTextView view = (CheckedTextView) super.getView(position, convertView, parent);
                 TagData tagData = allTags.get(position);
                 ThemeColor themeColor = themeCache.getThemeColor(tagData.getColor() >= 0 ? tagData.getColor() : 19);

src/main/java/com/todoroo/astrid/ui/HideUntilControlSet.java

@@ -9,6 +9,7 @@ import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -91,8 +92,9 @@ public class HideUntilControlSet extends TaskEditControlFragment implements OnIt
     public View onCreateView(final LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         View view = super.onCreateView(inflater, container, savedInstanceState);
         adapter = new HiddenTopArrayAdapter<HideUntilValue>(context, android.R.layout.simple_spinner_item, spinnerItems) {
+            @NonNull
             @Override
-            public View getView(int position, View convertView, ViewGroup parent) {
+            public View getView(int position, View convertView, @NonNull ViewGroup parent) {
                 int selectedItemPosition = position;
                 if (parent instanceof AdapterView) {
                     selectedItemPosition = ((AdapterView) parent).getSelectedItemPosition();

src/main/java/com/todoroo/astrid/ui/ReminderControlSet.java

@@ -11,6 +11,7 @@ import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.os.Parcelable;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -266,7 +267,7 @@ public class ReminderControlSet extends TaskEditControlFragment {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_LOCATION) {
             if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 pickLocation();

src/main/java/org/tasks/ErrorReportingSingleThreadExecutor.java

@@ -1,5 +1,7 @@
 package org.tasks;
 
+import android.support.annotation.NonNull;
+
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 
 import org.tasks.analytics.Tracker;
@@ -23,7 +25,7 @@ public class ErrorReportingSingleThreadExecutor implements Executor, Thread.Unca
     }
 
     @Override
-    public void execute(Runnable runnable) {
+    public void execute(@NonNull Runnable runnable) {
         try {
             executorService.execute(runnable);
         } catch (Exception e) {

src/main/java/org/tasks/dialogs/AddAttachmentDialog.java

@@ -3,6 +3,7 @@ package org.tasks.dialogs;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 
 import org.tasks.R;
 import org.tasks.injection.DialogFragmentComponent;
@@ -38,6 +39,7 @@ public class AddAttachmentDialog extends InjectingDialogFragment {
     private AddAttachmentCallback callback;
     private DialogInterface.OnCancelListener onCancelListener;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         List<String> entries = newArrayList();

src/main/java/org/tasks/dialogs/ColorPickerDialog.java

@@ -7,6 +7,7 @@ import android.content.Context;
 import android.content.DialogInterface;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.v4.content.ContextCompat;
 import android.support.v4.graphics.drawable.DrawableCompat;
 import android.view.LayoutInflater;
@@ -57,6 +58,7 @@ public class ColorPickerDialog extends InjectingDialogFragment {
     private ThemePickerCallback callback;
     private ArrayAdapter<String> adapter;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         if (savedInstanceState != null) {
@@ -70,9 +72,10 @@ public class ColorPickerDialog extends InjectingDialogFragment {
 
         final LayoutInflater inflater = theme.getLayoutInflater(context);
         adapter = new ArrayAdapter<String>(context, R.layout.color_selection_row, themes) {
+            @NonNull
             @SuppressLint("NewApi")
             @Override
-            public View getView(int position, View convertView, ViewGroup parent) {
+            public View getView(int position, View convertView, @NonNull ViewGroup parent) {
                 TextView textView = (TextView) (convertView == null
                         ? inflater.inflate(R.layout.color_selection_row, parent, false)
                         : convertView);

src/main/java/org/tasks/dialogs/SortDialog.java

@@ -4,6 +4,7 @@ import android.app.Activity;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.v7.app.AlertDialog;
 import android.view.View;
 import android.widget.Button;
@@ -47,6 +48,7 @@ public class SortDialog extends InjectingDialogFragment {
     private AlertDialog alertDialog;
     private SortDialogCallback callback;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

src/main/java/org/tasks/files/FileExplore.java

@@ -6,6 +6,7 @@ import android.content.pm.PackageManager;
 import android.net.Uri;
 import android.os.Bundle;
 import android.os.Environment;
+import android.support.annotation.NonNull;
 
 import com.google.common.base.Strings;
 import com.nononsenseapps.filepicker.FilePickerActivity;
@@ -76,7 +77,7 @@ public class FileExplore extends InjectingAppCompatActivity {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_FILE_WRITE) {
             if (grantResults.length > 0) {
                 if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {

src/main/java/org/tasks/preferences/AppCompatPreferenceActivity.java

@@ -20,6 +20,7 @@ import android.content.res.Configuration;
 import android.os.Bundle;
 import android.preference.PreferenceActivity;
 import android.support.annotation.LayoutRes;
+import android.support.annotation.NonNull;
 import android.support.v7.app.AppCompatDelegate;
 import android.view.MenuInflater;
 import android.view.View;
@@ -48,6 +49,7 @@ public abstract class AppCompatPreferenceActivity extends PreferenceActivity {
         getDelegate().onPostCreate(savedInstanceState);
     }
 
+    @NonNull
     @Override
     public MenuInflater getMenuInflater() {
         return getDelegate().getMenuInflater();

src/main/java/org/tasks/preferences/MiscellaneousPreferences.java

@@ -5,6 +5,7 @@ import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.preference.CheckBoxPreference;
 import android.speech.tts.TextToSpeech;
+import android.support.annotation.NonNull;
 
 import com.todoroo.astrid.voice.VoiceOutputAssistant;
 
@@ -141,7 +142,7 @@ public class MiscellaneousPreferences extends InjectingPreferenceActivity {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == PermissionRequestor.REQUEST_CALENDAR) {
             if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 calendarReminderPreference.setChecked(true);

src/main/java/org/tasks/ui/CalendarControlSet.java

@@ -10,6 +10,7 @@ import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
 import android.provider.CalendarContract;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -284,7 +285,7 @@ public class CalendarControlSet extends TaskEditControlFragment {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         if (requestCode == REQUEST_CODE_OPEN_EVENT) {
             if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 openCalendarEvent();

src/main/java/org/tasks/ui/DeadlineControlSet.java

@@ -5,6 +5,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.content.ContextCompat;
 import android.support.v4.graphics.drawable.DrawableCompat;
@@ -132,8 +133,9 @@ public class DeadlineControlSet extends TaskEditControlFragment {
         }
         final int overdueColor = getColor(context, R.color.overdue);
         dueDateAdapter = new HiddenTopArrayAdapter<String>(context, android.R.layout.simple_spinner_item, dueDateOptions) {
+            @NonNull
             @Override
-            public View getView(final int position, final View convertView, final ViewGroup parent) {
+            public View getView(final int position, final View convertView, @NonNull final ViewGroup parent) {
                 int selectedItemPosition = position;
                 if (parent instanceof AdapterView) {
                     selectedItemPosition = ((AdapterView) parent).getSelectedItemPosition();
@@ -157,8 +159,9 @@ public class DeadlineControlSet extends TaskEditControlFragment {
         dueDateSpinner.setAdapter(dueDateAdapter);
 
         dueTimeAdapter = new HiddenTopArrayAdapter<String>(context, android.R.layout.simple_spinner_item, dueTimeOptions, dueTimeHint) {
+            @NonNull
             @Override
-            public View getView(final int position, final View convertView, final ViewGroup parent) {
+            public View getView(final int position, final View convertView, @NonNull final ViewGroup parent) {
                 int selectedItemPosition = position;
                 if (parent instanceof AdapterView) {
                     selectedItemPosition = ((AdapterView) parent).getSelectedItemPosition();

src/main/java/org/tasks/ui/HiddenTopArrayAdapter.java

@@ -1,6 +1,7 @@
 package org.tasks.ui;
 
 import android.content.Context;
+import android.support.annotation.NonNull;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -26,7 +27,7 @@ public class HiddenTopArrayAdapter<T> extends ArrayAdapter<T> {
     }
 
     @Override
-    public View getDropDownView(final int position, final View convertView, final ViewGroup parent) {
+    public View getDropDownView(final int position, final View convertView, @NonNull final ViewGroup parent) {
         View v;
 
         if (position == 0) {