Improve code readability

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

@@ -234,8 +234,8 @@ public class CategorizationFragment extends Fragment {
 
     private Observable<CategoryItem> gpsCategories() {
         return Observable.fromIterable(
-                MwVolleyApi.GpsCatExists.getGpsCatExists() ?
-                        MwVolleyApi.getGpsCat() : new ArrayList<>())
+                MwVolleyApi.GpsCatExists.getGpsCatExists()
+                        ? MwVolleyApi.getGpsCat() : new ArrayList<>())
                 .map(name -> new CategoryItem(name, false));
     }
 
@@ -266,7 +266,7 @@ public class CategorizationFragment extends Fragment {
                     .map(name -> new CategoryItem(name, false));
         }
 
-        //otherwise if user has typed something in that isn't in cache, search API for matching categories
+        //otherwise, search API for matching categories
         return CommonsApplication.getInstance().getMWApi()
                 .allCategories(term, SEARCH_CATS_LIMIT)
                 .map(name -> new CategoryItem(name, false));
@@ -283,7 +283,7 @@ public class CategorizationFragment extends Fragment {
                 .map(s -> new CategoryItem(s, false));
     }
 
-    private boolean containsYear(String items) {
+    private boolean containsYear(String item) {
         //Check for current and previous year to exclude these categories from removal
         Calendar now = Calendar.getInstance();
         int year = now.get(Calendar.YEAR);
@@ -293,11 +293,11 @@ public class CategorizationFragment extends Fragment {
         String prevYearInString = String.valueOf(prevYear);
         Timber.d("Previous year: %s", prevYearInString);
 
-        //Check if s contains a 4-digit word anywhere within the string (.* is wildcard)
-        //And that s does not equal the current year or previous year
+        //Check if item contains a 4-digit word anywhere within the string (.* is wildcard)
+        //And that item does not equal the current year or previous year
         //And if it is an irrelevant category such as Media_needing_categories_as_of_16_June_2017(Issue #750)
-        return ((items.matches(".*(19|20)\\d{2}.*") && !items.contains(yearInString) && !items.contains(prevYearInString))
-                || items.matches("(.*)needing(.*)") || items.matches("(.*)taken on(.*)"));
+        return ((item.matches(".*(19|20)\\d{2}.*") && !item.contains(yearInString) && !item.contains(prevYearInString))
+                || item.matches("(.*)needing(.*)") || item.matches("(.*)taken on(.*)"));
     }
 
     private void updateCategoryCount(CategoryItem item, ContentProviderClient client) {
@@ -324,6 +324,9 @@ public class CategorizationFragment extends Fragment {
         return selectedCategories.size();
     }
 
+    /**
+     * Show dialog asking for confirmation to leave without saving categories.
+     */
     public void showBackButtonDialog() {
         new AlertDialog.Builder(getActivity())
                 .setMessage("Are you sure you want to go back? The image will not "

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

@@ -54,8 +54,12 @@ class CategoryItem implements Parcelable {
 
     @Override
     public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
 
         CategoryItem that = (CategoryItem) o;
 

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

@@ -57,7 +57,12 @@ public class Category {
         touch();
     }
 
-    // Database/content-provider stuff
+    //region Database/content-provider stuff
+
+    /**
+     * Persist category.
+     * @param client ContentProviderClient to handle DB connection
+     */
     public void save(ContentProviderClient client) {
         try {
             if (contentUri == null) {
@@ -78,7 +83,7 @@ public class Category {
         return cv;
     }
 
-    public static Category fromCursor(Cursor cursor) {
+    private static Category fromCursor(Cursor cursor) {
         // Hardcoding column positions!
         Category c = new Category();
         c.contentUri = CategoryContentProvider.uriForId(cursor.getInt(0));
@@ -88,6 +93,12 @@ public class Category {
         return c;
     }
 
+    /**
+     * Find persisted category in database, based on its name.
+     * @param client ContentProviderClient to handle DB connection
+     * @param name Category's name
+     * @return category from database, or null if not found
+     */
     public static @Nullable Category find(ContentProviderClient client, String name) {
         Cursor cursor = null;
         try {
@@ -112,8 +123,7 @@ public class Category {
     }
 
     /**
-     * Retrieves recently-used categories
-     *
+     * Retrieve recently-used categories, ordered by descending date.
      * @return a list containing recent categories
      */
     public static @NonNull ArrayList<String> recentCategories(ContentProviderClient client, int limit) {
@@ -198,4 +208,5 @@ public class Category {
             }
         }
     }
+    //endregion
 }