导航主机片段不显示任何片段

问题描述 投票：0回答：1

任何人都可以帮助我，我使用 mvvm 模型在我的应用程序中显示电影信息，我认为我做了所有正确的事情，但是当我运行我的应用程序时，它在片段中没有显示任何内容，并且主活动 xml 文件显示正确，但是当我启动我的应用程序没有显示任何内容 告诉我的错误。

片段类

class ListFragment : Fragment() {
lateinit var viewModel: MovieInfoViewModel
lateinit var adapter: MovieAdapter
private var _binding: FragmentListBinding?=null
private val binding get() = _binding!!

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View{
    _binding= FragmentListBinding.inflate(inflater,container,false)
    return binding.root
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    viewModel=(activity as MainActivity).viewModel
    setupRecyclerView()
    binding.icon.setOnClickListener {
        search()
    }
    findNavController().navigate(
        R.id.action_listFragment_to_searchFragment
    )
    var job: Job?=null
    binding.search.addTextChangedListener {it->
        job?.cancel()
        job= MainScope().launch {
            delay(500L)
            it?.let {
                if (it.toString().isNotEmpty()){
                    showShimmerAndHideRecycler()
                    viewModel.searchMovie(it.toString())
                }
            }
        }
    }
    viewModel.searchMovie.observe(viewLifecycleOwner,{response->
        when(response){
            is Resource.Success->{
                hideShimmerAndShowRecycler()
                response.data?.let {
                    searchResponse -> adapter.differ.submitList(searchResponse.Search)
                }
            }
            is Resource.Error->{
                hideShimmerAndShowRecycler()
                response.message?.let {
                    Toast.makeText(activity,"An error occurred: $it", Toast.LENGTH_SHORT).show()
                }
            }
            is Resource.Loading->{
                showShimmerAndHideRecycler()
            }
        }
    })
}
private fun hideShimmerAndShowRecycler(){
    binding.shimmerLayout.visibility=View.GONE
    binding.recycleview.visibility=View.VISIBLE
}
private fun showShimmerAndHideRecycler(){
    binding.recycleview.visibility=View.GONE
    binding.shimmerLayout.visibility=View.VISIBLE
    binding.shimmerLayout.startShimmer()
}
private fun setupRecyclerView(){
    adapter= MovieAdapter()
    binding.recycleview.apply {
        adapter=adapter
        layoutManager=LinearLayoutManager(activity)
    }
}
private fun search(){
    binding.icon.visibility=View.GONE
    binding.search.visibility=View.VISIBLE

}

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

}

Xml 文件

 <?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">

    <ImageButton
        android:id="@+id/icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:minHeight="48dp"
        android:src="@drawable/ic_baseline_search_24"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="SpeakableTextPresentCheck" />

    <EditText
        android:id="@+id/search"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:hint="Search"
        android:maxLines="1"
        android:visibility="invisible"
        android:minHeight="48dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:id="@+id/recycleview"
        android:layout_margin="10dp"
        app:layout_constraintTop_toBottomOf="@id/search"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        tools:listitem="@layout/adapter"/>

    <com.facebook.shimmer.ShimmerFrameLayout
        android:id="@+id/shimmerLayout"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/search"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:visibility="visible">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <include layout="@layout/shimmer_layout" />
            <include layout="@layout/shimmer_layout" />
            <include layout="@layout/shimmer_layout" />

        </LinearLayout>
    </com.facebook.shimmer.ShimmerFrameLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

主要活动

class MainActivity : AppCompatActivity() {
lateinit var navController: NavController
lateinit var viewModel: MovieInfoViewModel
private var _binding:ActivityMainBinding?=null
private val binding get() = _binding!!
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
    navController=navHostFragment.navController
    val repository=MovieRepository()
    val viewModelProviderFactory=MovieInfoViewModelProvider(application,repository)
    viewModel=ViewModelProvider(this,viewModelProviderFactory).get(MovieInfoViewModel::class.java)

}

xml 文件

    <?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">
    
    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph"
        tools:layout="@layout/fragment_list" />

清单文件

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.movieinfo">
    <uses-permission android:name="android.permission.INTERNET"/>

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
    android:name=".MovieApplication"
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/Theme.MovieInfo">
    <activity
        android:name=".MainActivity"
        android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

        

    <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

导航图 xml

 <?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/nav_graph"
app:startDestination="@id/listFragment">

<fragment
    android:id="@+id/listFragment"
    android:name="com.example.movieinfo.ui.fragment.ListFragment"
    android:label="ListFragment" >
    <action
        android:id="@+id/action_listFragment_to_searchFragment"
        app:destination="@id/searchFragment" />
</fragment>
<fragment
    android:id="@+id/searchFragment"
    android:name="com.example.movieinfo.ui.fragment.SearchFragment"
    android:label="fragment_search"
    tools:layout="@layout/fragment_search" >

</fragment>
android android-fragments mvvm fragment android-viewmodel
1个回答
0
投票

要在应用程序模块的build.gradle文件中添加旧版本的库，您可以修改实现行，如下所示：

实现“androidx.navigation：navigation-fragment-ktx：2.3.3” 实现“androidx.navigation：navigation-ui-ktx：2.3.3”

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