Bottom navigation bar listener not working

Question

So i just got started with android development a couple weeks ago, while trying to make navigation between two fragments with a bottom nav bar, for some reasons the click listener is just not working, no errors, no warnings, compiles no problem but it might be some logic problem? here's the code:

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val fragmentHome = HomeFragment()
        val fragmentProfile = ProfileFragment()

        replaceCurrentFragment(fragmentHome)

        NavigationBarView.OnItemSelectedListener { item ->
            when(item.itemId) {
                R.id.page_home -> {
                    Log.i("NavBar","Home pressed")
                    replaceCurrentFragment(fragmentHome)
                    true
                }
                R.id.page_profile -> {
                    Log.i("NavBar","Profile pressed")
                    replaceCurrentFragment(fragmentProfile)
                    true
                }
                else -> {
                    Log.i("NavBar","Error?")
                    false
                }
            }
        }
    }

    private fun replaceCurrentFragment(fragment: Fragment) =
        supportFragmentManager.beginTransaction().apply {
            replace(R.id.flFragment, fragment)
            commit()
        }
}

Layout:

<?xml version="1.0" encoding="utf-8"?>
<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=".MainActivity">

    <FrameLayout
        android:id="@+id/flFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        app:labelVisibilityMode="selected"
        android:id="@+id/bottom_navigation"
        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_navigation_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

Menu:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/page_home"
        android:icon="@drawable/ic_home"
        android:title="Home"/>
    <item
        android:id="@+id/page_profile"
        android:icon="@drawable/ic_profile"
        android:title="Profile"/>
</menu>

the main page does get initialized on the home fragment, but when i click the nav bar buttons, nothing happens so the problem is in that listener part, copy pasted from the docs yet it doesn't work.

i also have a bug where the layout editor doesn't show the nav bar contents, so my ide might be glitched? would appreciate any help.

Answer 1

Replace "NavigationBarView" with your actual bottomNavigationView id.

This would work,

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val fragmentHome = HomeFragment()
        val fragmentProfile = ProfileFragment()
        replaceCurrentFragment(fragmentHome)

val myBottomNavigationView = findViewById<BottomNavigationView>(R.id.bottom_navigation)

myBottomNavigationView.OnItemSelectedListener { item ->
            when(item.itemId) {
                R.id.page_home -> {
                    Log.i("NavBar","Home pressed")
                    replaceCurrentFragment(fragmentHome)
                    true
                }
                R.id.page_profile -> {
                    Log.i("NavBar","Profile pressed")
                    replaceCurrentFragment(fragmentProfile)
                    true
                }
                else -> {
                    Log.i("NavBar","Error?")
                    false
                }
            }
        }
    }

    private fun replaceCurrentFragment(fragment: Fragment) =
        supportFragmentManager.beginTransaction().apply {
            replace(R.id.flFragment, fragment)
            commit()
        }
}