sheishuoAPP/app/res/menu/notification_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/notification_menu_btn"
        android:icon="@drawable/notification_delete_selector"
        android:title=""
        app:showAsAction="always"/>
</menu>