Languages should start listening to preferences changes only after default values have been set

app/src/main/java/org/solovyev/android/calculator/language/Languages.java

@@ -30,7 +30,6 @@ public final class Languages implements SharedPreferences.OnSharedPreferenceChan
 
     public Languages(@Nonnull SharedPreferences preferences) {
         this.preferences = preferences;
-        this.preferences.registerOnSharedPreferenceChangeListener(this);
     }
 
     @Nullable
@@ -68,6 +67,13 @@ public final class Languages implements SharedPreferences.OnSharedPreferenceChan
         return null;
     }
 
+    /**
+     * This method should be called only when default values have been set to application's preferences
+     */
+    public void init() {
+        preferences.registerOnSharedPreferenceChangeListener(this);
+    }
+
     @Nonnull
     public List<Language> getList() {
         Check.isMainThread();