Show the correct last export date in the book manager.

All books appeared with the date from the active book instead.

Fixes #580

Author: rivaldi8

app/src/main/java/org/gnucash/android/ui/settings/BookManagerFragment.java

@@ -160,7 +160,7 @@ public void bindView(View view, final Context context, Cursor cursor) {
             final String bookUID = cursor.getString(cursor.getColumnIndexOrThrow(BookEntry.COLUMN_UID));
 
             TextView lastSyncText = (TextView) view.findViewById(R.id.last_sync_time);
-            lastSyncText.setText(PreferencesHelper.getLastExportTime().toString());
+            lastSyncText.setText(PreferencesHelper.getLastExportTime(bookUID).toString());
 
             TextView labelLastSync = (TextView) view.findViewById(R.id.label_last_sync);
             labelLastSync.setText(R.string.label_last_export_time);

app/src/main/java/org/gnucash/android/util/PreferencesHelper.java

@@ -84,4 +84,20 @@ public static Timestamp getLastExportTime() {
         Log.d(LOG_TAG, "Retrieving '" + utcString + "' as lastExportTime from Android Preferences.");
         return TimestampHelper.getTimestampFromUtcString(utcString);
     }
+
+    /**
+     * Get the time for the last export operation of a specific book.
+     *
+     * @return A {@link Timestamp} with the time.
+     */
+    public static Timestamp getLastExportTime(String bookUID) {
+        final String utcString =
+                GnuCashApplication.getAppContext()
+                .getSharedPreferences(bookUID, Context.MODE_PRIVATE)
+                .getString(PREFERENCE_LAST_EXPORT_TIME_KEY,
+                           TimestampHelper.getUtcStringFromTimestamp(
+                                TimestampHelper.getTimestampFromEpochZero()));
+        Log.d(LOG_TAG, "Retrieving '" + utcString + "' as lastExportTime from Android Preferences.");
+        return TimestampHelper.getTimestampFromUtcString(utcString);
+    }
 }