android: Actually show recently used in "Recent files" list

Previously, a set was used to store the recently used files,
meaning the order was lost when restoring from the prefs.

Use a space-delimited string to store the entries in prefs
instead, and convert that into an (ordered) list.
This way, it's possible to always drop the oldest entry
(instead of a random one) when inserting a new one and
the max count has been reached, so the list of
recently used files shows those that are actually the
(up to 4) most recently used ones.

Change the key used for the preference
(variable 'RECENT_DOCUMENTS_KEY') to a different value,
so there is no problem about trying to
read old values stored as a Set<String> as a
plain String.

Change-Id: I95cc3627cd2975f0463f5ecb94292a26fe714066
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/113462
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

1 files changed, 18 insertions, 19 deletions

diff --git a/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java b/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java
index e968f97b3a32..3236b53e7dc5 100644
--- a/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java
+++ b/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java
@@ -44,6 +44,7 @@ import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.Toolbar;
+import android.text.TextUtils;
 import android.util.Log;
 import android.view.ContextMenu;
 import android.view.ContextMenu.ContextMenuInfo;
@@ -125,7 +126,9 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
     public static final String EXPLORER_VIEW_TYPE_KEY = "EXPLORER_VIEW_TYPE";
     public static final String EXPLORER_PREFS_KEY = "EXPLORER_PREFS";
     public static final String SORT_MODE_KEY = "SORT_MODE";
-    private static final String RECENT_DOCUMENTS_KEY = "RECENT_DOCUMENTS";
+    private static final String RECENT_DOCUMENTS_KEY = "RECENT_DOCUMENT_URIS";
+    // delimiter used for storing multiple URIs in a string
+    private static final String RECENT_DOCUMENTS_DELIMITER = " ";
     private static final String ENABLE_SHOW_HIDDEN_FILES_KEY = "ENABLE_SHOW_HIDDEN_FILES";
     private static final String DISPLAY_LANGUAGE = "DISPLAY_LANGUAGE";
 
@@ -263,7 +266,8 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
 
         recentRecyclerView = findViewById(R.id.list_recent);
 
-        Set<String> recentFileStrings = prefs.getStringSet(RECENT_DOCUMENTS_KEY, new HashSet<String>());
+        String recentPref = prefs.getString(RECENT_DOCUMENTS_KEY, "");
+        List<String> recentFileStrings = Arrays.asList(recentPref.split(RECENT_DOCUMENTS_DELIMITER));
 
         final List<RecentFile> recentFiles = new ArrayList();
         for (String recentFileString : recentFileStrings) {
@@ -1088,7 +1092,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
             // ContentResolver#takePersistableUriPermission only available from SDK level 19 on
             Log.i(LOGTAG, "Recently used files not supported, requires SDK version >= 19.");
             // drop potential entries
-            prefs.edit().putStringSet(RECENT_DOCUMENTS_KEY, new HashSet<String>()).apply();
+            prefs.edit().putString(RECENT_DOCUMENTS_KEY, "").apply();
             return;
         }
 
@@ -1097,17 +1101,13 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         getContentResolver().takePersistableUriPermission(fileUri, Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
 
         String newRecent = fileUri.toString();
-        Set<String> recentsSet = prefs.getStringSet(RECENT_DOCUMENTS_KEY, new HashSet<String>());
+        List<String> recentsList = new ArrayList(Arrays.asList(prefs.getString(RECENT_DOCUMENTS_KEY, "").split(RECENT_DOCUMENTS_DELIMITER)));
 
-        //create array to work with
-        ArrayList<String> recentsArrayList = new ArrayList<String>(recentsSet);
-
-        //remove string if present, so that it doesn't appear multiple times
-        recentsSet.remove(newRecent);
-
-        //put the new value in the first place
-        recentsArrayList.add(0, newRecent);
+        // remove string if present, so that it doesn't appear multiple times
+        recentsList.remove(newRecent);
 
+        // put the new value in the first place
+        recentsList.add(0, newRecent);
 
         /*
          * 4 because the number of recommended items in App Shortcuts is 4, and also
@@ -1115,14 +1115,13 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
          */
         final int RECENTS_SIZE = 4;
 
-        while (recentsArrayList.size() > RECENTS_SIZE) {
-            recentsArrayList.remove(RECENTS_SIZE);
+        while (recentsList.size() > RECENTS_SIZE) {
+            recentsList.remove(RECENTS_SIZE);
         }
 
-        //switch to Set, so that it could be inserted into prefs
-        recentsSet = new HashSet<String>(recentsArrayList);
-
-        prefs.edit().putStringSet(RECENT_DOCUMENTS_KEY, recentsSet).apply();
+        // serialize to String that can be set for pref
+        String value = TextUtils.join(RECENT_DOCUMENTS_DELIMITER, recentsList);
+        prefs.edit().putString(RECENT_DOCUMENTS_KEY, value).apply();
 
         //update app shortcuts (7.0 and above)
         if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N_MR1) {
@@ -1132,7 +1131,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
             shortcutManager.removeAllDynamicShortcuts();
 
             ArrayList<ShortcutInfo> shortcuts = new ArrayList<ShortcutInfo>();
-            for (String recentDoc : recentsArrayList) {
+            for (String recentDoc : recentsList) {
                 Uri docUri = Uri.parse(recentDoc);
                 String filename = FileUtilities.retrieveDisplayNameForDocumentUri(getContentResolver(), docUri);
                 if (filename.isEmpty()) {