ProgressBar在将数据加载到活动（Xamarin.Android）中时会在某个时刻停止旋转]] << [

Question

我有以下屏幕：

当我单击Ponentes ImageButton时，ProgressBar会在加载Ponentes活动中的数据时出现。问题在于它在某个时候停止旋转。可能导致此问题的原因以及如何解决？

这里是ProgressBar Ponentes中的axml：

<ProgressBar
    android:id = "@+id/loadingSpinner"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:visibility="gone"
    android:gravity="center"/>

这里是OnCreate Ponentes的Activity方法：

protected override async void OnCreate(Bundle savedInstanceState)
{
    base.OnCreate(savedInstanceState);
    SetContentView(Resource.Layout.SpeakersActivity);

    Android.Widget.Toolbar toolbar = FindViewById<Android.Widget.Toolbar>(Resource.Id.toolbar);
    toolbar.NavigationOnClick += delegate
    {
        this.OnBackPressed();
    };


    loadingSpinner = FindViewById<ProgressBar>(Resource.Id.loadingSpinner);
    loadingSpinner.Visibility = ViewStates.Visible;
    await Task.Run(() =>
    {
        //get all the speakers from the db
        allSpeakers = DatabaseHelper.GetAllFromTable<Speaker>("speakers.db");

        //get only the international spakers
        internationalSpeakers = allSpeakers.Where(x => x.Nationality.Equals("international")).ToList();

        //get only the national speakers
        nationalSpeakers = allSpeakers.Where(x => x.Nationality.Equals("national")).ToList();

        RunOnUiThread(() =>
        {
            speakersRecyclerView = FindViewById<RecyclerView>(Resource.Id.speakersRecyclerView);
            speakersLayoutManager = new LinearLayoutManager(this);
            speakersRecyclerView.SetLayoutManager(speakersLayoutManager);
            speakersAdapter = new SpeakersAdapter(internationalSpeakers);
            speakersAdapter.ItemClick += OnItemClick;
            speakersRecyclerView.SetAdapter(speakersAdapter);

            loadingSpinner.Visibility = ViewStates.Gone;
        });
     });

     internationalSpeakersTextView = FindViewById<TextView>(Resource.Id.internationalSpeakersTextView);
     internationalSpeakersTextView.Click += delegate
     {
            //change TextViews's style when selected/not-selected
            internationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_selected);
            nationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_unselected);

            LoadSpeakers(internationalSpeakers);
     };

     nationalSpeakersTextView = FindViewById<TextView>(Resource.Id.nationalSpeakersTextView);
     nationalSpeakersTextView.Click += delegate
     {
            //change TextViews's style when selected/not-selected
            nationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_selected);
            internationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_unselected);

            LoadSpeakers(nationalSpeakers);
     };
}

[如果需要，我可以将整个Ponentes Activity]粘贴到您的位置>

我有以下屏幕：当我单击Ponentes ImageButton时，在加载Ponentes活动中的数据时会出现ProgressBar。问题在于它在某个时候停止旋转。什么...

Answer 1

SpeakersActivity.cs：

[Activity(Label = "SpeakersActivity", ScreenOrientation = ScreenOrientation.Portrait)]
public class SpeakersActivity : BaseActivity
{
    TextView internationalSpeakersTextView;

    TextView nationalSpeakersTextView;

    RecyclerView speakersRecyclerView;

    // Layout manager that lays out each card in the RecyclerView:
    RecyclerView.LayoutManager speakersLayoutManager;

    // Adapter that accesses the data set (speakers):
    SpeakersAdapter speakersAdapter;

    /// <summary>
    /// List that contains all the speakers
    /// </summary>
    List<Speaker> allSpeakers;

    /// <summary>
    /// List that contains the international speakers
    /// </summary>
    List<Speaker> internationalSpeakers;

    /// <summary>
    /// List that contains the national speakers
    /// </summary>
    List<Speaker> nationalSpeakers;

    ProgressBar loadingSpinner;

    protected override async void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        SetContentView(Resource.Layout.SpeakersActivity);

        Android.Widget.Toolbar toolbar = FindViewById<Android.Widget.Toolbar>(Resource.Id.toolbar);
        toolbar.NavigationOnClick += delegate
        {
            this.OnBackPressed();
        };

        loadingSpinner = FindViewById<ProgressBar>(Resource.Id.loadingSpinner);
        loadingSpinner.Visibility = ViewStates.Visible;
        await Task.Run(() =>
        {
            //get all the speakers from the db
            allSpeakers = GetAllSpeakers();

            //get only the international spakers
            internationalSpeakers = allSpeakers.Where(x => x.Nationality.Equals("international")).ToList();

            //get only the national speakers
            nationalSpeakers = allSpeakers.Where(x => x.Nationality.Equals("national")).ToList();

            RunOnUiThread(() =>
            {
                speakersRecyclerView = FindViewById<RecyclerView>(Resource.Id.speakersRecyclerView);
                speakersLayoutManager = new LinearLayoutManager(this);
                speakersRecyclerView.SetLayoutManager(speakersLayoutManager);
                LoadSpeakers(internationalSpeakers);

                loadingSpinner.Visibility = ViewStates.Gone;
            });
        });

        internationalSpeakersTextView = FindViewById<TextView>(Resource.Id.internationalSpeakersTextView);
        internationalSpeakersTextView.Click += delegate
        {
            //change TextViews's style when selected/not-selected
            internationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_selected);
            nationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_unselected);

            LoadSpeakers(internationalSpeakers);
        };

        nationalSpeakersTextView = FindViewById<TextView>(Resource.Id.nationalSpeakersTextView);
        nationalSpeakersTextView.Click += delegate
        {
            //change TextViews's style when selected/not-selected
            nationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_selected);
            internationalSpeakersTextView.SetBackgroundResource(Resource.Drawable.textView_unselected);

            LoadSpeakers(nationalSpeakers);
        };
    }

    /// <summary>
    /// Load speakers inside activity
    /// </summary>
    /// <param name="speakers">speakers</param>
    private void LoadSpeakers(List<Speaker> speakers)
    {
        speakersAdapter = new SpeakersAdapter(speakers);
        speakersAdapter.ItemClick += OnItemClick;
        speakersRecyclerView.SetAdapter(speakersAdapter);
    }

    private void OnItemClick(object sender, string speakerResumeUrl)
    {
        var speakerDetailsActivity = new Intent(this, typeof(SpeakerDetailsActivity));
        speakerDetailsActivity.PutExtra("speakerResumeUrl", speakerResumeUrl);
        StartActivity(speakerDetailsActivity);
    }

    public override void OnBackPressed()
    {
        StartActivity(typeof(CongressActivity));
        Finish();
    }

private List<Speaker> GetAllSpeakers()
    {
        System.Threading.Thread.Sleep(4000);

        List<Speaker> speakers = new List<Speaker>();
        speakers.Add(new Speaker { Photo = "https://i.imgur.com/DDH2Ckk.png", Name = "Anne-Maree Keenan", Resume = "https://51congresopodologia.com/?page_id=4004", Nationality = "international" });
        speakers.Add(new Speaker { Photo = "https://i.imgur.com/DDH2Ckk.png", Name = "Anthony Redmond", Resume = "https://51congresopodologia.com/?page_id=4004", Nationality = "international" });
        speakers.Add(new Speaker { Photo = "https://i.imgur.com/DDH2Ckk.png", Name = "Chris Nester", Resume = "https://51congresopodologia.com/?page_id=4004", Nationality = "national" });
        speakers.Add(new Speaker { Photo = "https://i.imgur.com/DDH2Ckk.png", Name = "Amol Saxena", Resume = "https://51congresopodologia.com/?page_id=4004", Nationality = "international" });

        return speakers;
    }
}