diff --git a/src_253F周希奥代码注释/DropdownMenu.java b/src_253F周希奥代码注释/DropdownMenu.java
new file mode 100644
index 0000000..7302c67
--- /dev/null
+++ b/src_253F周希奥代码注释/DropdownMenu.java
@@ -0,0 +1,49 @@
+package net.micode.notes.ui;
+ 
+import android.content.Context;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.widget.Button;
+import android.widget.PopupMenu;
+import android.widget.PopupMenu.OnMenuItemClickListener;
+ 
+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();
+            }
+        });
+    }
+ 
+    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
+}
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