diff --git a/app/src/main/java/net/micode/notes/ui/DropdownMenu.java b/app/src/main/java/net/micode/notes/ui/DropdownMenu.java
index 613dc74..c831a9b 100644
--- a/app/src/main/java/net/micode/notes/ui/DropdownMenu.java
+++ b/app/src/main/java/net/micode/notes/ui/DropdownMenu.java
@@ -1,19 +1,3 @@
-/*
- * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *        http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
 package net.micode.notes.ui;
 
 import android.content.Context;
@@ -30,14 +14,18 @@ import net.micode.notes.R;
 public class DropdownMenu {
     private Button mButton;
     private PopupMenu mPopupMenu;
+    //声明一个下拉菜单
     private Menu mMenu;
 
     public DropdownMenu(Context context, Button button, int menuId) {
         mButton = button;
         mButton.setBackgroundResource(R.drawable.dropdown_icon);
+        //设置这个view的背景
         mPopupMenu = new PopupMenu(context, mButton);
         mMenu = mPopupMenu.getMenu();
         mPopupMenu.getMenuInflater().inflate(menuId, mMenu);
+        //MenuInflater是用来实例化Menu目录下的Menu布局文件
+        //根据ID来确认menu的内容选项
         mButton.setOnClickListener(new OnClickListener() {
             public void onClick(View v) {
                 mPopupMenu.show();
@@ -48,14 +36,14 @@ public class DropdownMenu {
     public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
         if (mPopupMenu != null) {
             mPopupMenu.setOnMenuItemClickListener(listener);
-        }
+        }//设置菜单的监听
     }
 
     public MenuItem findItem(int id) {
         return mMenu.findItem(id);
-    }
+    }//对于菜单选项的初始化，根据索引搜索菜单需要的选项
 
     public void setTitle(CharSequence title) {
         mButton.setText(title);
-    }
-}
+    }//布局文件，设置标题
+}
\ No newline at end of file