Navigation Component for app navigation

package com.example.myapp.ui.posts

import android.os.Bundle
import android.view.View
import androidx.fragment.app.Fragment
import androidx.fragment.app.viewModels
import androidx.lifecycle.lifecycleScope
import androidx.navigation.fragment.findNavController
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.myapp.R
import com.example.myapp.databinding.FragmentPostsBinding
import dagger.hilt.android.AndroidEntryPoint
import kotlinx.coroutines.launch

@AndroidEntryPoint
class PostsFragment : Fragment(R.layout.fragment_posts) {

    private var _binding: FragmentPostsBinding? = null
    private val binding get() = _binding!!

    private val viewModel: PostsViewModel by viewModels()
    private val adapter = PostsAdapter(
        onPostClick = { post -> navigateToDetail(post.id, post.title) }
    )

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        _binding = FragmentPostsBinding.bind(view)

        setupRecyclerView()
        setupObservers()
        setupFab()
    }

    private fun setupRecyclerView() {
        binding.recyclerView.apply {
            layoutManager = LinearLayoutManager(context)
            adapter = this@PostsFragment.adapter
        }
    }

    private fun setupObservers() {
        viewLifecycleOwner.lifecycleScope.launch {
            viewModel.uiState.collect { state ->
                adapter.submitList(state.posts)
                binding.progressBar.visibility =
                    if (state.isLoading) View.VISIBLE else View.GONE

                state.error?.let { error ->
                    // Show error message
                }
            }
        }
    }

    private fun setupFab() {
        binding.fab.setOnClickListener {
            findNavController().navigate(
                R.id.action_posts_to_create
            )
        }
    }

    private fun navigateToDetail(postId: Int, title: String) {
        val action = PostsFragmentDirections
            .actionPostsToDetail(postId, title)
        findNavController().navigate(action)
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

package com.example.myapp.ui

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.fragment.NavHostFragment
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.navigateUp
import androidx.navigation.ui.setupActionBarWithNavController
import androidx.navigation.ui.setupWithNavController
import com.example.myapp.R
import com.example.myapp.databinding.ActivityMainBinding
import dagger.hilt.android.AndroidEntryPoint

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private lateinit var appBarConfiguration: AppBarConfiguration

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

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

        // Setup bottom navigation
        binding.bottomNav.setupWithNavController(navController)

        // Setup toolbar
        appBarConfiguration = AppBarConfiguration(
            setOf(R.id.postsFragment, R.id.profileFragment)
        )
        setupActionBarWithNavController(navController, appBarConfiguration)

        // Handle deep links
        navController.handleDeepLink(intent)
    }

    override fun onSupportNavigateUp(): Boolean {
        val navHostFragment = supportFragmentManager
            .findFragmentById(R.id.nav_host_fragment) as NavHostFragment
        val navController = navHostFragment.navController
        return navController.navigateUp(appBarConfiguration) || super.onSupportNavigateUp()
    }
}