How to remove bottom navigation bar from login screen

Issue

ScreenShot of login screen with bottom navigation bar

Hi, I am facing an issue in my university project. In the image above you can see that in my login screen there is a bottom navigation bar which I want to remove but everything I've tried ended up in compilation issues. My MainActivity.KT is

package com.example.integratedmodulateoroperationroom

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.Menu
import android.view.MenuItem
import androidx.navigation.NavController
import androidx.navigation.fragment.NavHostFragment
import androidx.navigation.fragment.findNavController
import androidx.navigation.ui.*
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    private lateinit var navController: NavController
    private lateinit var appBarConfiguration: AppBarConfiguration
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
        navController = navHostFragment.findNavController()

        appBarConfiguration = AppBarConfiguration(
            setOf(R.id.homeFragment, R.id.loginFragment),
            drawer_layout
        )

        setSupportActionBar(toolbar)
        setupActionBarWithNavController(navController, appBarConfiguration)

        bottom_nav.setupWithNavController(navController)
    }

    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.options_menu, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        return item.onNavDestinationSelected(navController) || super.onOptionsItemSelected(item)
    }

    override fun onSupportNavigateUp(): Boolean {
        return navController.navigateUp(appBarConfiguration) || super.onSupportNavigateUp()
    }
}

Main_Activity.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout
    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:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/design_default_color_primary"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/bottom_nav"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/toolbar"
        app:navGraph="@navigation/nav_graph" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_nav"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_nav_menu" />

    </androidx.constraintlayout.widget.ConstraintLayout>

    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_gravity="start"
        app:menu="@menu/drawer_nav_menu"
        android:layout_width="wrap_content"
        android:layout_height="match_parent" />

</androidx.drawerlayout.widget.DrawerLayout>

LoginFragment.KT

package com.example.integratedmodulateoroperationroom

import android.os.Bundle
import android.view.View
import androidx.fragment.app.Fragment
import androidx.navigation.fragment.findNavController
import kotlinx.android.synthetic.main.fragment_login.*

class LoginFragment : Fragment (R.layout.fragment_login) {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        button_goToHomeScreen.setOnClickListener {
            val action = LoginFragmentDirections.actionLoginFragmentToHomeFragment()
            findNavController().navigate(action)
        }
    }
}

fragment_login

<androidx.constraintlayout.widget.ConstraintLayout 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=".LoginFragment">

    <EditText
        android:id="@+id/editTextTextPersonName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="Login ID"
        android:inputType="textPersonName"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editTextTextPassword"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:hint="Password"
        android:inputType="textPassword"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextTextPersonName" />

    <Button
        android:id="@+id/button_goToHomeScreen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="Login"
        app:backgroundTint="#9E9E9E"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextTextPassword" />

    <ImageView
        android:id="@+id/imageView4"
        android:layout_width="0dp"
        android:layout_height="274dp"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:src="@drawable/logo"
        app:layout_constraintBottom_toTopOf="@+id/editTextTextPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Nav_graph

<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/nav_graph"
    app:startDestination="@id/homeFragment">

    <fragment
        android:id="@+id/homeFragment"
        android:name="com.example.integratedmodulateoroperationroom.HomeFragment"
        android:label="Integrated Module OR (Operation Room)"
        tools:layout="@layout/fragment_home">
        <action
            android:id="@+id/action_homeFragment_to_otFragment"
            app:destination="@id/otFragment"
            app:enterAnim="@anim/slide_in_right"
            app:exitAnim="@anim/slide_out_left"
            app:popEnterAnim="@anim/slide_in_left"
            app:popExitAnim="@anim/slide_out_right" />
        <action
            android:id="@+id/action_homeFragment_to_surgicalFragment"
            app:destination="@id/surgicalFragment"
            app:enterAnim="@anim/slide_in_right"
            app:exitAnim="@anim/slide_out_left"
            app:popEnterAnim="@anim/slide_in_left"
            app:popExitAnim="@anim/slide_out_right" />
        <action
            android:id="@+id/action_homeFragment_to_laminarFragment"
            app:destination="@id/laminarFragment" />
    </fragment>
    <fragment
        android:id="@+id/otFragment"
        android:name="com.example.integratedmodulateoroperationroom.OtFragment"
        android:label="OT Lights"
        tools:layout="@layout/fragment_ot" />
    <fragment
        android:id="@+id/surgicalFragment"
        android:name="com.example.integratedmodulateoroperationroom.SurgicalFragment"
        android:label="Surgical Lights"
        tools:layout="@layout/fragment_surgical" />
    <fragment
        android:id="@+id/settingsFragment"
        android:name="com.example.integratedmodulateoroperationroom.SettingsFragment"
        android:label="Settings"
        tools:layout="@layout/fragment_settings" />
    <fragment
        android:id="@+id/laminarFragment"
        android:name="com.example.integratedmodulateoroperationroom.LaminarFragment"
        android:label="Laminar Airflow"
        tools:layout="@layout/fragment_laminar" />
    <fragment
        android:id="@+id/loginFragment"
        android:name="com.example.integratedmodulateoroperationroom.LoginFragment"
        android:label="Login"
        tools:layout="@layout/fragment_login" >
        <action
            android:id="@+id/action_loginFragment_to_homeFragment"
            app:destination="@id/homeFragment"
            app:enterAnim="@anim/slide_in_right"
            app:exitAnim="@anim/slide_out_left"
            app:popEnterAnim="@anim/slide_in_left"
            app:popExitAnim="@anim/slide_out_right" />
    </fragment>
</navigation>

Solution

NavController offers an OnDestinationChangedListener interface that is called when the NavController's current destination or its arguments change which can be used to update UI elements such as BottomNavigationBar as you navigate between fragments.

MainActivity.KT

// in oncreate

private val bottomNavigationView = findViewById<BottomNavigationView>(R.id.bottom_nav)

navController.addOnDestinationChangedListener { _, destination, _ ->
   bottomNavigationView.visibility = if(destination.id == R.id.loginFragment) {
       View.GONE
   } else {
       View.VISIBLE
   }
}

link to official docs here and for more info check this one

Answered By - Sekiro