Bottom navigation bar listener not working-CodePudding

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.

CodePudding user response：

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()
        }
}