How to set exactly same height for Android bottom navigation bar with these codes?

Question

I am writing codes for Android app. The layout is scrollview fragment is up, and bottom navigation bar down. It displays menu items well and click event works well, however, depending on contents amount displayed in fragment, bottom navigation bar's height is slightly changing.

What solution for this phenomenon? The following is the codes for this:

MainActivity.kt

package info.shutterpress.idols

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import androidx.navigation.fragment.NavHostFragment
import androidx.navigation.ui.setupWithNavController
import androidx.databinding.DataBindingUtil.setContentView
import com.google.android.material.bottomnavigation.BottomNavigationView
import info.shutterpress.idols.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    lateinit var view: View

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView<ActivityMainBinding>(this, R.layout.activity_main)

        val navHostFragment =
            supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
        val navController = navHostFragment.navController
        val mBottomNavView = findViewById<BottomNavigationView>(R.id.bottom_navigation_view)
        mBottomNavView.setupWithNavController(navController)
        mBottomNavView.visibility = View.VISIBLE
        view = mBottomNavView

        val mBottomNavigationView = view as BottomNavigationView
        mBottomNavigationView.setOnNavigationItemSelectedListener { mi ->
            when (mi.itemId) {
                R.id.home_dest -> {
                    navController.navigate(R.id.main_fragment)
                }
                R.id.list_dest -> {
                    navController.navigate(R.id.recyclerview_fragment)
                }
                R.id.quiz_dest -> {
                }
            }
            true
        }
    }
}

MainFragment.kt

package info.shutterpress.idols

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import info.shutterpress.idols.databinding.FragmentMainBinding

class MainFragment : Fragment() {
    lateinit var bind: FragmentMainBinding
    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        bind = DataBindingUtil.inflate(inflater, R.layout.fragment_main, container, false)
        return bind.root
    }
}

ListFragment.kt

package info.shutterpress.idols

import android.content.res.TypedArray
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import androidx.navigation.findNavController
import androidx.navigation.fragment.findNavController
import androidx.recyclerview.widget.RecyclerView
import info.shutterpress.idols.databinding.FragmentRecyclerviewBinding

class ListFragment : Fragment() {
    lateinit var bind: FragmentRecyclerviewBinding
    var title: Array<String>? = null
    var image: TypedArray? = null

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        super.onCreateView(inflater, container, savedInstanceState)
        bind = DataBindingUtil.inflate(inflater, R.layout.fragment_recyclerview, container, false)
        title = resources.getStringArray(R.array.idols_title_array)
        image = resources.obtainTypedArray(R.array.idols_list_image_array)
        var adapter = IdolsListAdapter(image, title) {
            position -> onListItemClick(position)
        }
        bind.idolsList.adapter = adapter
        return bind.root
    }

    private fun onListItemClick(position: Int) {
        val action = ListFragmentDirections.actionRecyclerviewFragmentToDetailFragment(position)
        findNavController().navigate(action)
    }

    inner class ListHolder(
        view: View,
        private val onItemClicked: (position: Int) -> Unit
    ) : RecyclerView.ViewHolder(view), View.OnClickListener {
        var titleTextView: TextView = view.findViewById(R.id.detail_item_title)
        var imageView: ImageView = view.findViewById(R.id.detail_item_image)

        init {
            view.setOnClickListener(this)
        }

        override fun onClick(v: View) {
            val position = adapterPosition
            onItemClicked(position)
        }
    }

    inner class IdolsListAdapter(
        var image: TypedArray?,
        var title: Array<String>?,
        val onItemClicked: (position: Int) -> Unit) :
        RecyclerView.Adapter<ListHolder>() {

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) : ListHolder {
            val view = layoutInflater.inflate(R.layout.item_view, parent, false)
            return ListHolder(view, onItemClicked)
        }

        override fun getItemCount() = title!!.size

        override fun onBindViewHolder(holder: ListHolder, position: Int) {
            var _image = image!!.getResourceId(position, -1)
            var _title = title!![position]
            holder.apply {
                titleTextView.text = _title
                imageView.setImageResource(_image)
            }
        }
    }
}

DetailFragment.kt

package info.shutterpress.idols

import android.content.res.TypedArray
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import androidx.navigation.fragment.navArgs
import info.shutterpress.idols.databinding.FragmentDetailBinding

class DetailFragment : Fragment() {
    lateinit var bind: FragmentDetailBinding
    var title: Array<String>? = null
    var image: TypedArray? = null
    var description: Array<String>? = null

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        bind = DataBindingUtil.inflate(inflater, R.layout.fragment_detail, container, false)

        val args by navArgs<DetailFragmentArgs>()
        var _position = args.positionDatum

        title = resources.getStringArray(R.array.idols_title_array)
        image = resources.obtainTypedArray(R.array.idols_list_image_array)
        description = resources.getStringArray(R.array.idols_description_array)

        bind.writingDetailTitle.text = title!![_position]
        bind.writingDetailImage.setImageResource(image!!.getResourceId(_position, -1))
        bind.writingDetailContent.text = description!![_position]

        return bind.root
    }
}

activity_main.xml

<layout 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">

    <data/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/darkBeige"
        android:layout_margin="0dp"
        android:paddingBottom="0dp"
        android:orientation="vertical"
        tools:context="info.shutterpress.idols.MainActivity">

        <androidx.fragment.app.FragmentContainerView
            android:id="@+id/nav_host_fragment"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            app:defaultNavHost="true"
            app:navGraph="@navigation/nav_main" />

        <com.google.android.material.bottomnavigation.BottomNavigationView
            app:menu="@menu/menu_bottom_navigation"
            android:id="@+id/bottom_navigation_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight=".1"
            android:padding="10dp"
            android:theme="@style/Theme.bottomNavApp"
            app:backgroundTint="@color/beige"
            app:background="@color/beige"
            app:itemIconTint="@color/black"
            app:itemTextColor="@color/black" />

    </LinearLayout>
</layout>

fragment_detail.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

    </data>

    <LinearLayout
        android:id="@+id/detail_outermost_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="0dp"
        android:paddingBottom="0dp"
        android:layout_margin="0dp"
        android:background="@color/darkBeige"
        android:gravity="start"
        android:orientation="vertical">
        <TextView
            android:id="@+id/writing_detail_title"
            android:padding="4dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dp"
            android:paddingTop="10dp"
            android:gravity="center"
            android:textSize="35sp"
            android:textColor="#FFFFFF"
            android:textStyle="bold"/>

        <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/darkBeige"
            android:paddingTop="0dp"
            android:paddingBottom="0dp"
            android:scrollbarSize="12dip" >
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingTop="0dp"
                android:paddingBottom="0dp"
                android:layout_marginTop="20dp"
                android:background="@color/darkBeige"
                android:gravity="start"
                android:orientation="vertical">

                <ImageView
                    android:id="@+id/writing_detail_image"
                    android:layout_width="320dp"
                    android:layout_height="320dp"
                    android:layout_gravity="center"
                    android:layout_marginTop="20dp"
                    app:srcCompat="@drawable/idols1" />

                <TextView
                    android:id="@+id/writing_detail_content"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:background="@color/darkBeige"
                    android:layout_marginTop="20dp"
                    android:layout_marginBottom="25dp"
                    android:paddingTop="0dp"
                    android:padding="20dp"
                    android:gravity="start"
                    android:textSize="@dimen/text_size_main"
                    android:textColor="#de000000"
                    android:lineSpacingExtra="@dimen/line_spacing_main"/>

            </LinearLayout>
        </ScrollView>
    </LinearLayout>
</layout>

fragment_main.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>

    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="0dp"
        android:paddingBottom="0dp"
        android:layout_margin="0dp"
        android:background="@color/darkBeige"
        android:gravity="start"
        android:orientation="vertical">
        <TextView
            android:padding="4dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/app_name"
            android:paddingTop="10dp"
            android:gravity="center"
            android:textSize="35sp"
            android:textColor="#FFFFFF"
            android:textStyle="bold"/>

        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/darkBeige"
            android:layout_margin="0dp"
            android:paddingTop="0dp"
            android:paddingBottom="0dp"
            android:scrollbarSize="12dip" >
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:paddingTop="0dp"
                android:paddingBottom="0dp"
                android:layout_margin="0dp"
                android:background="@color/darkBeige"
                android:gravity="start"
                android:orientation="vertical">

                <TextView
                    android:id="@+id/welcome_message"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:background="@color/darkBeige"
                    android:layout_margin="0dp"
                    android:paddingTop="0dp"
                    android:padding="20dp"
                    android:gravity="start"
                    android:textSize="@dimen/text_size_main"
                    android:lineSpacingExtra="@dimen/line_spacing_main"
                    android:text="@string/welcome_message"
                    android:textColor="#de000000" />

            </LinearLayout>
        </ScrollView>
    </LinearLayout>
</layout>

fragment_recyclerview.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">
    <data>
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="35dp"
        android:id="@+id/recyclerview_fragment">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/idols_list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
            tools:context="info.shutterpress.idols.MainActivity"
            tools:listitem="@layout/item_view"/>

    </LinearLayout>
</layout>

Answer 1

I have asked expert and he gave me appropriate solution! This works!

First, from activity_main.xml,

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" // this should be 0dp
        android:layout_weight="1"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_main" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        app:menu="@menu/menu_bottom_navigation"
        android:id="@+id/bottom_navigation_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight=".1" // this should be deleted
        android:padding="10dp"
        android:theme="@style/Theme.bottomNavApp"
        app:backgroundTint="@color/beige"
        app:background="@color/beige"
        app:itemIconTint="@color/black"
        app:itemTextColor="@color/black" />

This works! It was layout XML problem, not Kotlin code.