Injected the CategoryDao where needed.

app/src/main/java/fr/free/nrw/commons/category/CategorizationFragment.java

@@ -1,6 +1,5 @@
 package fr.free.nrw.commons.category;
 
-import android.content.ContentProviderClient;
 import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.support.v7.app.AlertDialog;
@@ -48,7 +47,6 @@ import timber.log.Timber;
 
 import static android.view.KeyEvent.ACTION_UP;
 import static android.view.KeyEvent.KEYCODE_BACK;
-import static fr.free.nrw.commons.category.CategoryContentProvider.AUTHORITY;
 
 /**
  * Displays the category suggestion and selection screen. Category search is initiated here.
@@ -70,12 +68,12 @@ public class CategorizationFragment extends DaggerFragment {
 
     @Inject MediaWikiApi mwApi;
     @Inject @Named("default_preferences") SharedPreferences prefs;
+    @Inject CategoryDao categoryDao;
 
     private RVRendererAdapter<CategoryItem> categoriesAdapter;
     private OnCategoriesSaveHandler onCategoriesSaveHandler;
     private HashMap<String, ArrayList<String>> categoriesCache;
     private List<CategoryItem> selectedCategories = new ArrayList<>();
-    private ContentProviderClient databaseClient;
 
     private final CategoriesAdapterFactory adapterFactory = new CategoriesAdapterFactory(item -> {
         if (item.isSelected()) {
@@ -141,7 +139,6 @@ public class CategorizationFragment extends DaggerFragment {
     @Override
     public void onDestroy() {
         super.onDestroy();
-        databaseClient.release();
     }
 
     @Override
@@ -179,7 +176,6 @@ public class CategorizationFragment extends DaggerFragment {
         setHasOptionsMenu(true);
         onCategoriesSaveHandler = (OnCategoriesSaveHandler) getActivity();
         getActivity().setTitle(R.string.categories_activity_title);
-        databaseClient = getActivity().getContentResolver().acquireContentProviderClient(AUTHORITY);
     }
 
     private void updateCategoryList(String filter) {
@@ -262,7 +258,7 @@ public class CategorizationFragment extends DaggerFragment {
     }
 
     private Observable<CategoryItem> recentCategories() {
-        return Observable.fromIterable(new CategoryDao(databaseClient).recentCategories(SEARCH_CATS_LIMIT))
+        return Observable.fromIterable(categoryDao.recentCategories(SEARCH_CATS_LIMIT))
                 .map(s -> new CategoryItem(s, false));
     }
 
@@ -313,7 +309,6 @@ public class CategorizationFragment extends DaggerFragment {
     }
 
     private void updateCategoryCount(CategoryItem item) {
-        CategoryDao categoryDao = new CategoryDao(databaseClient);
         Category category = categoryDao.find(item.getName());
 
         // Newly used category...

app/src/main/java/fr/free/nrw/commons/data/CategoryDao.java

@@ -12,25 +12,33 @@ import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
 
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Provider;
+
 import fr.free.nrw.commons.category.CategoryContentProvider;
 
 public class CategoryDao {
 
-    private final ContentProviderClient client;
+    private final Provider<ContentProviderClient> clientProvider;
 
-    public CategoryDao(ContentProviderClient client) {
-        this.client = client;
+    @Inject
+    public CategoryDao(@Named("category") Provider<ContentProviderClient> clientProvider) {
+        this.clientProvider = clientProvider;
     }
 
     public void save(Category category) {
+        ContentProviderClient db = clientProvider.get();
         try {
             if (category.getContentUri() == null) {
-                category.setContentUri(client.insert(CategoryContentProvider.BASE_URI, toContentValues(category)));
+                category.setContentUri(db.insert(CategoryContentProvider.BASE_URI, toContentValues(category)));
             } else {
-                client.update(category.getContentUri(), toContentValues(category), null, null);
+                db.update(category.getContentUri(), toContentValues(category), null, null);
             }
         } catch (RemoteException e) {
             throw new RuntimeException(e);
+        } finally {
+            db.release();
         }
     }
 
@@ -43,8 +51,9 @@ public class CategoryDao {
     public @Nullable
     Category find(String name) {
         Cursor cursor = null;
+        ContentProviderClient db = clientProvider.get();
         try {
-            cursor = client.query(
+            cursor = db.query(
                     CategoryContentProvider.BASE_URI,
                     Table.ALL_FIELDS,
                     Table.COLUMN_NAME + "=?",
@@ -60,6 +69,7 @@ public class CategoryDao {
             if (cursor != null) {
                 cursor.close();
             }
+            db.release();
         }
         return null;
     }
@@ -73,8 +83,9 @@ public class CategoryDao {
     List<String> recentCategories(int limit) {
         List<String> items = new ArrayList<>();
         Cursor cursor = null;
+        ContentProviderClient db = clientProvider.get();
         try {
-            cursor = client.query(
+            cursor = db.query(
                     CategoryContentProvider.BASE_URI,
                     Table.ALL_FIELDS,
                     null,
@@ -91,6 +102,7 @@ public class CategoryDao {
             if (cursor != null) {
                 cursor.close();
             }
+            db.release();
         }
         return items;
     }

app/src/main/java/fr/free/nrw/commons/di/CommonsApplicationModule.java

@@ -1,5 +1,6 @@
 package fr.free.nrw.commons.di;
 
+import android.content.ContentProviderClient;
 import android.content.SharedPreferences;
 import android.preference.PreferenceManager;
 import android.support.v4.util.LruCache;
@@ -26,6 +27,8 @@ import static android.content.Context.MODE_PRIVATE;
 @Module
 @SuppressWarnings({"WeakerAccess", "unused"})
 public class CommonsApplicationModule {
+    public static final String CATEGORY_AUTHORITY = "fr.free.nrw.commons.categories.contentprovider";
+
     private CommonsApplication application;
 
     public CommonsApplicationModule(CommonsApplication application) {
@@ -37,6 +40,12 @@ public class CommonsApplicationModule {
         return new AccountUtil(application);
     }
 
+    @Provides
+    @Named("category")
+    public ContentProviderClient provideContentProviderClient() {
+        return application.getContentResolver().acquireContentProviderClient(CATEGORY_AUTHORITY);
+    }
+
     @Provides
     @Named("application_preferences")
     public SharedPreferences providesApplicationSharedPreferences() {

app/src/test/java/fr/free/nrw/commons/data/CategoryDaoTest.java

@@ -50,20 +50,20 @@ import static org.mockito.Mockito.when;
 public class CategoryDaoTest {
 
     @Mock
-    ContentProviderClient client;
+    private ContentProviderClient client;
     @Mock
-    SQLiteDatabase database;
+    private SQLiteDatabase database;
     @Captor
-    ArgumentCaptor<ContentValues> captor;
+    private ArgumentCaptor<ContentValues> captor;
     @Captor
-    ArgumentCaptor<String[]> queryCaptor;
+    private ArgumentCaptor<String[]> queryCaptor;
 
     private CategoryDao testObject;
 
     @Before
     public void setUp() throws Exception {
         MockitoAnnotations.initMocks(this);
-        testObject = new CategoryDao(client);
+        testObject = new CategoryDao(() -> client);
     }
 
     @Test