Android 为什么底部导航抽屉片段显示空数据

我正在开发新闻应用程序，我已经创建了带有片段的底部导航，在topheadlinesfragment中，我正在使用改型获得新闻数据，但它显示的是空的白色屏幕 在下面

下面是我的主要活动，在这里我用片段实现了bottomnavigationdrawer

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

       val  bottomNavigationView = findViewById<BottomNavigationView>(R.id.bottom)



        bottomNavigationView.setOnNavigationItemSelectedListener {

            var selectedFragment = Fragment()
            when (it.itemId) {
                R.id.top_headline -> selectedFragment = TopHeadlinesFragment()

                R.id.espn_news -> selectedFragment = ESPNFragment()
                R.id.bbc_sport -> selectedFragment = BBCSportFragment()
                R.id.football_italia -> selectedFragment = FootballItaliaFragment()
            }
            val transaction = supportFragmentManager.beginTransaction()
            transaction.replace(R.id.frame_layout, selectedFragment)
            transaction.commit()
            return@setOnNavigationItemSelectedListener true

        }
    }
}

“E/RecyclerView:未连接适配器；”您未初始化适配器

我不确定它是否能解决您的问题，但首先将布局更改为：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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/main_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout 
        android:id="@+id/frame_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:layout_gravity="bottom"
        app:menu="@menu/bottomnews_nav"
        android:id="@+id/bottom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</FrameLayout>

“E/RecyclerView:未连接适配器；”您没有初始化适配器

我不确定它是否能解决您的问题，但首先将布局更改为：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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/main_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout 
        android:id="@+id/frame_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:layout_gravity="bottom"
        app:menu="@menu/bottomnews_nav"
        android:id="@+id/bottom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</FrameLayout>

---

你的问题是你的回收视图没有出现在头条标题上。
在

TopHeadlinesFragment

class TopHeadlinesFragment : Fragment() {
    var topHeadlinesAdapter: TopHeadlinesAdapter? = null

    //3
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view =  inflater.inflate(
            R.layout.fragment_top_headlines
            , container, false
        )

       val recyclerView = view.findViewById (R.id.recyclerView) as RecyclerView
        topHeadlinesAdapter = TopHeadlinesAdapter(recyclerView.context)

        recyclerView.layoutManager = LinearLayoutManager(context)
        recyclerView.adapter = topHeadlinesAdapter


        val apiInterface = SportNewsInterface.create().getNews()


        apiInterface.enqueue(object : Callback<SportNewsResponse> {
            override fun onResponse(
                call: Call<SportNewsResponse>?,
                response: Response<SportNewsResponse>?
            ) {

                if (response!!.body() != null) {
                    topHeadlinesAdapter!!.setMovieListItems(response.body()!!.articles)
                }
            }

            override fun onFailure(call: Call<SportNewsResponse>?, t: Throwable?) {

            }
        })
        return view
    }
}

class-TopHeadlinesFragment:Fragment（）{
变量topHeadlinesAdapter:topHeadlinesAdapter？=null
//3
覆盖创建视图(
充气机，
容器：视图组？，
savedInstanceState:捆绑？
)：查看{
val视图=充气机。充气(
R.layout.fragment_顶部标题
，货柜，虚假
)
val recyclerView=view.findviewbyd（R.id.recyclerView）作为recyclerView
topHeadlinesAdapter=topHeadlinesAdapter（recyclerView.context）
recyclerView.layoutManager=LinearLayoutManager（上下文）
recyclerView.adapter=topHeadlinesAdapter
val apiInterface=SportNewsInterface.create（）.getNews（）
排队（对象：回调{
覆盖响应(
呼叫：呼叫？，
回应：回应？
) {
if（response！！.body（）！=null）{
topHeadlinesAdapter！！.setMovieListItems（response.body（）！！.articles）
}
}
覆盖失效时的乐趣（调用：调用？、t:可丢弃？）{
}
})
返回视图
}
}

你的问题是你的回收视图没有出现在头条标题上。
在

TopHeadlinesFragment

class TopHeadlinesFragment : Fragment() {
    var topHeadlinesAdapter: TopHeadlinesAdapter? = null

    //3
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view =  inflater.inflate(
            R.layout.fragment_top_headlines
            , container, false
        )

       val recyclerView = view.findViewById (R.id.recyclerView) as RecyclerView
        topHeadlinesAdapter = TopHeadlinesAdapter(recyclerView.context)

        recyclerView.layoutManager = LinearLayoutManager(context)
        recyclerView.adapter = topHeadlinesAdapter


        val apiInterface = SportNewsInterface.create().getNews()


        apiInterface.enqueue(object : Callback<SportNewsResponse> {
            override fun onResponse(
                call: Call<SportNewsResponse>?,
                response: Response<SportNewsResponse>?
            ) {

                if (response!!.body() != null) {
                    topHeadlinesAdapter!!.setMovieListItems(response.body()!!.articles)
                }
            }

            override fun onFailure(call: Call<SportNewsResponse>?, t: Throwable?) {

            }
        })
        return view
    }
}

class-TopHeadlinesFragment:Fragment（）{
变量topHeadlinesAdapter:topHeadlinesAdapter？=null
//3
覆盖创建视图(
充气机，
容器：视图组？，
savedInstanceState:捆绑？
)：查看{
val视图=充气机。充气(
R.layout.fragment_顶部标题
，货柜，虚假
)
val recyclerView=view.findviewbyd（R.id.recyclerView）作为recyclerView
topHeadlinesAdapter=topHeadlinesAdapter（recyclerView.context）
recyclerView.layoutManager=LinearLayoutManager（上下文）
recyclerView.adapter=topHeadlinesAdapter
val apiInterface=SportNewsInterface.create（）.getNews（）
排队（对象：回调{
覆盖响应(
呼叫：呼叫？，
回应：回应？
) {
if（response！！.body（）！=null）{
topHeadlinesAdapter！！.setMovieListItems（response.body（）！！.articles）
}
}
覆盖失效时的乐趣（调用：调用？、t:可丢弃？）{
}
})
返回视图
}
}

您是否收到任何异常或警告？你从你的API得到响应了吗？Maor Hadad我从我使用PostAnalyso检查的API得到响应，所以为片段添加一个容器。frame_layout是主布局，在其中添加一个新的framelayout以包含碎片，但是你在应用程序中得到了它吗？请验证它。如果您将代码上传到bitbucket或github，这样我也可以运行它，这会很有帮助。您的意思是，在片段内部，我不明白。您是否收到任何异常或警告？你从你的API得到响应了吗？Maor Hadad我从我使用PostAnalyso检查的API得到响应，所以为片段添加一个容器。frame_layout是主布局，在其中添加一个新的framelayout以包含碎片，但是你在应用程序中得到了它吗？请验证它。如果您将代码上传到bitbucket或github，这样我也可以运行它，这会很有帮助。您的意思是在片段内部我不明白。我已经添加了log@MaorHadad请检查它。我已经添加了log@MaorHadad请检查它

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

2019-10-10 15:23:07.818 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout
2019-10-10 15:23:08.324 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout
2019-10-10 15:23:09.497 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout
2019-10-10 15:23:12.277 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout
2019-10-10 15:23:14.761 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout
2019-10-10 15:23:21.146 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout
2019-10-10 15:23:21.452 27558-27558/yodgorbek.komilov.musobaqayangiliklari E/RecyclerView: No adapter attached; skipping layout

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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/main_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout 
        android:id="@+id/frame_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:layout_gravity="bottom"
        app:menu="@menu/bottomnews_nav"
        android:id="@+id/bottom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</FrameLayout>

class TopHeadlinesFragment : Fragment() {
    var topHeadlinesAdapter: TopHeadlinesAdapter? = null

    //3
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view =  inflater.inflate(
            R.layout.fragment_top_headlines
            , container, false
        )

       val recyclerView = view.findViewById (R.id.recyclerView) as RecyclerView
        topHeadlinesAdapter = TopHeadlinesAdapter(recyclerView.context)

        recyclerView.layoutManager = LinearLayoutManager(context)
        recyclerView.adapter = topHeadlinesAdapter


        val apiInterface = SportNewsInterface.create().getNews()


        apiInterface.enqueue(object : Callback<SportNewsResponse> {
            override fun onResponse(
                call: Call<SportNewsResponse>?,
                response: Response<SportNewsResponse>?
            ) {

                if (response!!.body() != null) {
                    topHeadlinesAdapter!!.setMovieListItems(response.body()!!.articles)
                }
            }

            override fun onFailure(call: Call<SportNewsResponse>?, t: Throwable?) {

            }
        })
        return view
    }
}