LocaleList is not properly sorted, so do our own best approx.

It seems that LocaleList does not necessarily return the "Language
Priority List" in the order that the user has prioritized things. So
we have to kind of fake it by first adding the default locale, then
adding the locales from LocaleList based on longest order first (e.g.
de-AT then de).

#987

app/src/main/java/org/fdroid/fdroid/data/App.java

@@ -443,9 +443,22 @@ public class App extends ValueObject implements Comparable<App>, Parcelable {
 
         Set<String> availableLocales = localized.keySet();
         Set<String> localesToUse = new LinkedHashSet<>();
+        if (availableLocales.contains(localeTag)) {
+            localesToUse.add(localeTag);
+        }
+        if (availableLocales.contains(languageTag)) {
+            localesToUse.add(languageTag);
+        }
         if (Build.VERSION.SDK_INT >= 24) {
             LocaleList localeList = Resources.getSystem().getConfiguration().getLocales();
-            for (String toUse : localeList.toLanguageTags().split(",")) {
+            String[] sortedLocaleList = localeList.toLanguageTags().split(",");
+            Arrays.sort(sortedLocaleList, new java.util.Comparator<String>() {
+                @Override
+                public int compare(String s1, String s2) {
+                    return s1.length() - s2.length();
+                }
+            });
+            for (String toUse : sortedLocaleList) {
                 localesToUse.add(toUse);
                 for (String l : availableLocales) {
                     if (l.equals(toUse.split("-")[0])) {
@@ -455,12 +468,6 @@ public class App extends ValueObject implements Comparable<App>, Parcelable {
                 }
             }
         } else {
-            if (availableLocales.contains(localeTag)) {
-                localesToUse.add(localeTag);
-            }
-            if (availableLocales.contains(languageTag)) {
-                localesToUse.add(languageTag);
-            }
             for (String l : availableLocales) {
                 if (l.startsWith(languageTag)) {
                     localesToUse.add(l);
@@ -506,6 +513,18 @@ public class App extends ValueObject implements Comparable<App>, Parcelable {
         tvScreenshots = getLocalizedListEntry(localized, localesToUse, "tvScreenshots");
     }
 
+    /**
+     * Returns the right localized version of this entry, based on an immitation of
+     * the logic that Android/Java uses.  On Android >= 24, this can get the
+     * "Language Priority List", but it doesn't always seem to be properly sorted.
+     * So this method has to kind of fake it by using {@link Locale#getDefault()}
+     * as the first entry, then sorting the rest based on length (e.g. {@code de-AT}
+     * before {@code de}).
+     *
+     * @see LocaleList
+     * @see Locale#getDefault()
+     * @see java.util.Locale.LanguageRange
+     */
     private String getLocalizedEntry(Map<String, Map<String, Object>> localized,
                                      Set<String> locales, String key) {
         try {
@@ -800,14 +819,13 @@ public class App extends ValueObject implements Comparable<App>, Parcelable {
      * Attempts to find the installed {@link Apk} from the database. If not found, will lookup the
      * {@link InstalledAppProvider} to find the details of the installed app and use that to
      * instantiate an {@link Apk} to be returned.
-     *
+     * <p>
      * Cases where an {@link Apk} will not be found in the database and for which we fall back to
      * the {@link InstalledAppProvider} include:
-     *  + System apps which are provided by a repository, but for which the version code bundled
+     * <li>System apps which are provided by a repository, but for which the version code bundled
-     *    with the system is not included in the repository.
+     * with the system is not included in the repository.</li>
-     *  + Regular apps from a repository, where the installed version is old enough that it is no
+     * <li>Regular apps from a repository, where the installed version is old enough that it is no
-     *    longer available in the repository.
+     * longer available in the repository.</li>
-     *
      */
     @Nullable
     public Apk getInstalledApk(Context context) {
@@ -1185,7 +1203,7 @@ public class App extends ValueObject implements Comparable<App>, Parcelable {
      * However, if the app is installed, then we override this and instead want to only encourage
      * the user to try and install versions with that signature (because thats all the OS will let
      * them do).
-     *
+     * <p>
      * Will return null for any {@link App} which represents media (instead of an apk) and thus
      * doesn't have a signer.
      */