单击导航抽屉中的菜单项后如何打开子菜单?

我实现了一个带有导航视图的导航抽屉.而且我正在通过menu.xml文件在导航视图中增加价值.

I implemented a navigation drawer, with navigation view. and i am adding value in navigation view through a menu.xml file.

<android.support.design.widget.NavigationView
android:id="@+id/nvView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:itemTextColor="@android:color/white"
android:background="?attr/colorAccent"
app:menu="@menu/drawer_view"
app:headerLayout="@layout/nav_header"
>
</android.support.design.widget.NavigationView>

一切正常，但是我遇到了一个问题，我想在菜单上单击后显示子菜单.

every thing is working fine, but i am facing a problem, I want to display submenu's , after click on menu.

我尝试了很多事情，例如:-

I tried many thing's like:-

我在菜单项中的menu.xml中添加子菜单. 这样的东西.

I add submenu in menu.xml, inside item. somthing like this..

<menu xmlns:android="http://schemas.android.com/apk/res/android">
<group android:checkableBehavior="single">

<item
    android:id="@+id/nav_ChangeOutlet_fragment"
    android:icon="@drawable/home_icon"
    android:title="@string/changeOutlet"
    android:checked="true">
    <menu>
        <group>
            <item
                android:title="one"></item>
            <item
                android:title="two"></item>
            <item
                android:title="three"></item>

        </group>
    </menu>

然后它像这样返回我的输出.

then it return me output like this.

输出:单击此链接以查看输出

Output: click on this link to see output

https://drive.google.com/file/d/0B0B9-WZYydK7RG1yY0tRdkhOSWW8 /view?usp =共享

现在的问题是，以这种方式我无法单击menu，只有子菜单可在此处单击.

Now problem is that, in this way i am not able to click on menu , only sub menu are clickable here.

我要在这里显示子菜单，仅在单击菜单后，否则子菜单确实显示给其他人或说它处于不可见状态

I want here to show sub menu , only after click on menu, otherwise sub menu does shown to other or say it is in invisible state