diff --git a/app/src/main/java/com/kunfei/bookshelf/view/activity/MainActivity.java b/app/src/main/java/com/kunfei/bookshelf/view/activity/MainActivity.java
index 7de594103f..49b1820ee9 100644
--- a/app/src/main/java/com/kunfei/bookshelf/view/activity/MainActivity.java
+++ b/app/src/main/java/com/kunfei/bookshelf/view/activity/MainActivity.java
@@ -485,6 +485,9 @@ private void setUpNavigationView() {
         });
     }
 
+    /**
+     * 更新主题切换按钮
+     */
     private void upThemeVw() {
         if (isNightTheme()) {
             vwNightTheme.setImageResource(R.drawable.ic_daytime_24dp);