MainActivity.kt

		package com.example.bottomnavigationkotlin
		
		import android.os.Bundle
		import com.google.android.material.bottomnavigation.BottomNavigationView
		import androidx.appcompat.app.AppCompatActivity
		import androidx.navigation.fragment.NavHostFragment
		import androidx.navigation.ui.AppBarConfiguration
		import androidx.navigation.ui.setupWithNavController
		
		class MainActivity : AppCompatActivity() {
		    override fun onCreate(savedInstanceState: Bundle?) {
		        super.onCreate(savedInstanceState)
		        setContentView(R.layout.activity_main)
		
		        val navView: BottomNavigationView = findViewById(R.id.navBottomNavigationView)
		
		        val navHostFragment = supportFragmentManager.findFragmentById(R.id.navFragmentContainerView) as NavHostFragment
		        val navController = navHostFragment.navController
		
		        AppBarConfiguration(navController.graph)
		        navView.setupWithNavController(navController)
		    }
		}