Android Kotlin； 尽管设置了背景透明，为什么它从底部导航视图显示白色背景？

Question

The problem is that it is showing a white background in the bottomnavigationview, but I want it to have transparent. Why is it doing this?

So looks my android app:

Here is my code:

<com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:itemRippleColor="#00931E30"
        android:outlineAmbientShadowColor="#00931E30"
        android:outlineSpotShadowColor="#00931E30"
        android:visibility="visible"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="1.0"
        app:menu="@menu/bottom_menu"
        tools:visibility="visible">

I have also tried setting the background of the bottomnavigationview with this:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="@android:color/transparent" />
</shape>

as well as through programming:

 bottomNavigationView.background = ColorDrawable(Color.TRANSPARENT)
 bottomNavigationView.itemBackgroundResource = R.drawable.transparent

I don't know where the issue is and would be grateful if anyone knows the solution.

The entire XML of the activity looks so:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.MainActivity">

    <ImageView
        android:id="@+id/imgBackground"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scaleType="centerInside"
        android:src="@drawable/ic_launcher_track"
        tools:ignore="MissingConstraints" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:itemRippleColor="#AD931E30"
        android:background="#028C8C8C"
        android:outlineAmbientShadowColor="#00931E30"
        android:elevation="10dp"
        android:layout_alignParentBottom= "true"
        android:visibility="visible"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintVertical_bias="1.0"
        app:menu="@menu/bottom_menu"
        tools:visibility="visible"
        >



        <com.google.android.material.tabs.TabItem
            android:background="#00424242"
            android:id="@+id/go_to_home"
            android:layout_width="100dp"
            android:layout_height="70dp"
            android:onClick="goToHome"
            android:text="schmutz">

        </com.google.android.material.tabs.TabItem>

        <com.google.android.material.tabs.TabItem
            android:id="@+id/go_to_dash"
            android:layout_width="100dp"
            android:layout_height="70dp"
            android:layout_marginLeft="100dp"
            android:onClick="goToDash"
            android:text="schmutz" />

        <com.google.android.material.tabs.TabItem
            android:id="@+id/go_to_not"
            android:layout_width="100dp"
            android:layout_height="70dp"
            android:layout_marginLeft="180dp"
            android:onClick="goToNotification"
            android:text="schmutz" />

        <com.google.android.material.tabs.TabItem
            android:id="@+id/go_to_profile"
            android:layout_width="100dp"
            android:layout_height="70dp"
            android:layout_marginLeft="260dp"
            android:text="schmutz"
            android:onClick="goToProfile"/>

    </com.google.android.material.bottomnavigation.BottomNavigationView>

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_tablayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabIndicatorColor="#00B8B8B8"
        app:tabIndicatorHeight="3dp"
        app:tabMode="fixed"
        tools:ignore="MissingConstraints" />

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="675dp"
        android:layout_alignParentBottom="true"
        android:layout_marginTop="?attr/actionBarSize"
        android:layout_marginBottom="?attr/actionBarSize"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintVertical_bias="1.0" />

    <fragment
        android:id="@+id/fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="1000dp"
        android:layout_marginBottom="56dp"
        app:defaultNavHost="true"
        app:flow_horizontalAlign="center"
        app:flow_verticalAlign="center"
        app:navGraph="@navigation/my_nav"
        tools:layout_editor_absoluteX="-27dp"
        tools:layout_editor_absoluteY="278dp">
    </fragment>
</RelativeLayout>

Answer 1

try this code;

BottomNavigationView navView = findViewById(R.id.nav_view);
navView.setBackgroundColor(ContextCompat.getColor(getApplicationContext(), android.R.color.transparent));

Answer 2

Can you post the entire activity's XML? I wanna see which views are child to which and which are parent to which.

I am not exactly sure why you wanna make it transparent. Anyway, this issue usually happens because there is nothing under the bottom navigation bar. In other words, it's covering nothing but the actual activity's background. I am not also sure if you want the navigation bar to float over the recyclerview or not.

Try making the recyclerview's lower constraints reach the screen's lower edge.