gistfile1.txt

package com.company107.myapplication.UI

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.PersistableBundle
import androidx.navigation.NavController
import androidx.navigation.Navigation
import androidx.navigation.ui.NavigationUI
import com.company107.myapplication.R

import kotlinx.android.synthetic.main.activity_main.*;

class MainActivity : AppCompatActivity() {

    private lateinit var navController :NavController

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

        setSupportActionBar(toolbar)

        navController = Navigation.findNavController(this, R.id.main_fragment)
        NavigationUI.setupWithNavController(bottom_nav,navController)
        NavigationUI.setupActionBarWithNavController(this, navController)


    }

    override fun onSaveInstanceState(outState: Bundle?, outPersistentState: PersistableBundle?) {
        super.onSaveInstanceState(outState, outPersistentState)
    }

    override fun onSupportNavigateUp(): Boolean {
        return NavigationUI.navigateUp(navController,null)
    }

}