Android ProgressBar赢得'；不要在代码中的任何地方加载

所以我试了一整天都没有成功

我连接了两个片段，带有ViewPager表格布局

我试着在每个片段上添加ProgressBar，但它不会出现。 我还试着把它放在启动两个片段的ViewPager的主活动上，它也不会显示

我尝试了一个新项目，它显示了。我做错了什么

我已经在代码中删除了ProgressBar，因为它不起作用。如果你能亲眼看到，这是代码

第一个片段

public class FilmShow extends Fragment {
    private static RecyclerView recyclerView;
    private static final String API_KEY = "2e08750083b7e21e96e915011d3f8e2d";
    private static final String TAG = FilmShow.class.getSimpleName();

public FilmShow() {
    // Required empty public constructor
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getResponse getResponse = new getResponse();
    getResponse.execute();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_film_show, container, false);

    recyclerView = view.findViewById(R.id.recycler_tv);

    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext());
    recyclerView.setLayoutManager(layoutManager);

    recyclerView.setVisibility(View.GONE);



    return view;
}

private class getResponse extends AsyncTask<Void, Void, Void> {

    @Override
    protected Void doInBackground(Void... voids) {
        ApiInterface apiInterface = ApiClient.getList().create(ApiInterface.class);

        Call<Response> responseCall = apiInterface.getFilmList(API_KEY);
        responseCall.enqueue(new Callback<Response>() {
            @Override
            public void onResponse(Call<Response> call, retrofit2.Response<Response> response) {
                List<ResultsItem> resultsItemList = response.body().getResults();
                recyclerView.setAdapter(new FilmShowRecyclerAdapter(resultsItemList, getContext()));
            }

            @Override
            public void onFailure(Call<Response> call, Throwable t) {
                Log.d(TAG, t.toString());
            }
        });
        return null;
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
    }
}

}

编辑：

修改了另一个片段以在onCreateView上显示ProgressBar，它可以工作，但不会停止加载

...............

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    final View view = inflater.inflate(R.layout.fragment_tv_show, container, false);

    recyclerView = view.findViewById(R.id.recycler_tv);
    progressBar = view.findViewById(R.id.progress_bar);

    ...............

XML文件

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    android:padding="16dp"
    >



        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_tv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context="@layout/item_tv"
            android:visibility="gone" />


        <Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <ProgressBar
            android:id="@+id/progress_bar"
            style="?android:attr/progressBarStyle"
            android:textAlignment="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            />


</RelativeLayout>

---

java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“android.view.view android.widget.ProgressBar.findViewById（int）”

您尝试过这样做吗

 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    final View view = inflater.inflate(R.layout.fragment_tv_show, container, false);

    recyclerView = view.findViewById(R.id.recycler_tv);
    progressBar = view.findViewById(R.id.progress_bar);

// progress bar Shows first
progressBar.setVisibility(VISIBLE);

ApiInterface apiInterface = ApiClient.getList().create(ApiInterface.class);

        Call<Response> responseCall = apiInterface.getFilmList(API_KEY);
        responseCall.enqueue(new Callback<Response>() {
            @Override
            public void onResponse(Call<Response> call, retrofit2.Response<Response> response) {
                List<ResultsItem> resultsItemList = response.body().getResults();
                recyclerView.setAdapter(new FilmShowRecyclerAdapter(resultsItemList, getContext()));
progressBar.setVisibility(GONE);

            }

            @Override
            public void onFailure(Call<Response> call, Throwable t) {
                Log.d(TAG, t.toString());
        progressBar.setVisibility(GONE);

            }
        });

@覆盖
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
//为该碎片膨胀布局
最终视图=充气机。充气（R.layout.fragment\u tv\u show，容器，假）；
recyclerView=view.findViewById（R.id.recycler\u tv）；
progressBar=view.findviewbyd（R.id.progress\u-bar）；
//首先显示进度条
progressBar.setVisibility（可见）；
ApiInterface ApiInterface=ApiClient.getList（）.create（ApiInterface.class）；
调用responseCall=apinterface.getFilmList（API_键）；
responseCall.enqueue（新的回调（）{
@凌驾
公共void onResponse（呼叫，改装2.响应）{
List resultsItemList=response.body（）.getResults（）；
setAdapter（新的FilmShowRecyclerAdapter（resultsItemList，getContext（））；
progressBar.setVisibility（已消失）；
}
@凌驾
失败时公共无效（调用调用，可丢弃的t）{
Log.d（TAG，t.toString（））；
progressBar.setVisibility（已消失）；
}
});

---

此代码不需要Asyntask，我只是让它隐藏和显示

您需要显示如何实现和显示/隐藏progressbar，否则很难从上面了解问题发生的位置。@Azhar92内部实现onProgress和onPostExecute不起作用我不明白为什么在Async内部使用改型任务库。两者具有相似的特性function@NandaZ完成assignmentjava.lang.NullPointerException需要它：尝试调用虚拟方法'void android.widget.ProgressBar.setVisibility（int）'在空对象引用上，您必须先在xml中设置Progressbar小部件，然后在fraagmentprivate静态Progressbar Progressbar中实例化它；@Override public void onCreate（@Nullable Bundle savedInstanceState）{super.onCreate（savedInstanceState）；Progressbar.findViewById（R.id.progress\u bar）；progressBar.setVisibility（可见）；我编辑了我的答案，我在

onCreateView

方法中更改了执行。如果您在后台执行Asyntask，而您的状态无法访问主线程。Main thead只允许在执行后访问，但在您的情况下，这不合适。Asyntask是执行HttpRest的经典示例，如果您使用改型，您可以执行Asyncta它们在功能上是相同的

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    android:padding="16dp"
    >



        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_tv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context="@layout/item_tv"
            android:visibility="gone" />


        <Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <ProgressBar
            android:id="@+id/progress_bar"
            style="?android:attr/progressBarStyle"
            android:textAlignment="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            />


</RelativeLayout>

public class TvShow extends Fragment {
    private static RecyclerView recyclerView;
    private static final String API_KEY = "2e08750083b7e21e96e915011d3f8e2d";
    private static final String TAG = TvShow.class.getSimpleName();
    private static ProgressBar progressBar;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        progressBar.findViewById(R.id.progress_bar);

        progressBar.setVisibility(VISIBLE);


        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                CallInternet callInternet = new CallInternet();
                callInternet.execute();
            }
        });

        thread.run();
    }

    public TvShow() {
        // Required empty public constructor
    }

 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    final View view = inflater.inflate(R.layout.fragment_tv_show, container, false);

    recyclerView = view.findViewById(R.id.recycler_tv);
    progressBar = view.findViewById(R.id.progress_bar);

// progress bar Shows first
progressBar.setVisibility(VISIBLE);

ApiInterface apiInterface = ApiClient.getList().create(ApiInterface.class);

        Call<Response> responseCall = apiInterface.getFilmList(API_KEY);
        responseCall.enqueue(new Callback<Response>() {
            @Override
            public void onResponse(Call<Response> call, retrofit2.Response<Response> response) {
                List<ResultsItem> resultsItemList = response.body().getResults();
                recyclerView.setAdapter(new FilmShowRecyclerAdapter(resultsItemList, getContext()));
progressBar.setVisibility(GONE);

            }

            @Override
            public void onFailure(Call<Response> call, Throwable t) {
                Log.d(TAG, t.toString());
        progressBar.setVisibility(GONE);

            }
        });