I want to remove a bar on NavigationView layout

解語花 :

I create a NavigationView ,it success.
but it has a bit bug. I hope I can remove this green and gray bar.(when I create NavigationView,it would appear...
I dont know how to do it.

this is my code:

xml:

 <androidx.drawerlayout.widget.DrawerLayout
    android:id="@+id/drawerLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    >
    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="240dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:menu="@menu/activity_miaoli_menu"
        />

</androidx.drawerlayout.widget.DrawerLayout>

menu:

<menu xmlns:android="http://schemas.android.com/apk/res/android">
<group android:checkableBehavior="single">
    <item
        android:id="@+id/nav_home"
        android:icon="@drawable/ic_menu_camera"
        android:title="@string/menu_home" />
    <item
        android:id="@+id/nav_gallery"
        android:icon="@drawable/ic_menu_gallery"
        android:title="@string/menu_gallery" />   
</group>
</menu>

nav.java

 Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
     drawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
     navigationView = (NavigationView) findViewById(R.id.nav_view);

    ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this,
            drawerLayout, toolbar, R.string.open, R.string.close);
    drawerLayout.addDrawerListener(actionBarDrawerToggle);
    actionBarDrawerToggle.syncState();
    navigationView.bringToFront();

anyone can help me? thank in advance.

Rasel :

Add layout_behavior for root child of coordinate layout in your layout.

app:layout_behavior="@string/appbar_scrolling_view_behavior"