更改片段时显示 ProgressBar - Android

Question

我的应用程序中有一个片段，它执行大量后台工作，因此需要很长时间才能加载。我想在我的 Main Activity 中显示一个 ProgressBar，并在加载片段后将其隐藏。

问题是，进度条不显示，或者卡住了，因为整个 UI 冻结了。

如何在片段加载时显示 ProgressBar？
谢谢。

编辑：片段内的代码：

  public override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        // Create your fragment here

        fragments = new Fragment[]
       {
           new HalachotFragment(),
           new BooksFragment(),
       };

        var titles = CharSequence.ArrayFromStringArray(new[]
       {
                "הלכות",
                "ספרים",
        });

        tabsAdapter = new TabsFragmentPagerAdapter(ChildFragmentManager, fragments, titles);

    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        // Use this to return your custom view for this Fragment

        var view = inflater.Inflate(Resource.Layout.HalachaSection, container, false);

        //var progressBar = Activity.FindViewById<ProgressBar>(Resource.Id.progressBar);

        halachotPager = view.FindViewById<ViewPager>(Resource.Id.halachotPager);

        halachotPager.Adapter = tabsAdapter;
        halachotPager.OffscreenPageLimit = 2;
        halachotPager.SetCurrentItem(1, true);
        // Bind the tabs to the ViewPager
        tabs = Activity.FindViewById<TabLayout>(Resource.Id.tabs);

        tabs.SetupWithViewPager(halachotPager);
        //var toolbar = Activity.FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
        tabs.Visibility = ViewStates.Visible;

        //progressBar.Visibility = ViewStates.Gone;
        return view;

    }

书片段：

        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        // Use this to return your custom view for this Fragment
        // return inflater.Inflate(Resource.Layout.YourFragment, container, false);
        View view = inflater.Inflate(Resource.Layout.Books, container, false);

        mRecyclerView = view.FindViewById<RecyclerView>(Resource.Id.booksRecyclerView);
        mRecyclerView.NestedScrollingEnabled = false;

        mBooks = new List<Book>();
        ImageView cover = new ImageView(Activity);
        //cover = view.FindViewById<ImageView>(Resource.Id.coverImage);
        cover.SetImageResource(Resource.Drawable.Torat_Hamachane1);
        mBooks.Add(new Book() { Title = "תורת המחנה א' - הלכות יום ויום", Cover = cover, imageResourceId = Resource.Drawable.Torat_Hamachane1}); 

        //Create our layout manager
        mLayoutManager = new GridLayoutManager(Activity, 2);
        mLayoutManager.AutoMeasureEnabled = true;
        //mRecyclerView.SetForegroundGravity(GravityFlags.CenterHorizontal);
        mRecyclerView.SetLayoutManager(mLayoutManager);
        SimpleItemAnimator x = null;

        mRecyclerView.SetItemAnimator(x);
        mAdapter = new RecyclerAdapter(mBooks, mRecyclerView, Activity);
        mRecyclerView.SetAdapter(mAdapter);
        cover = new ImageView(Activity);
        cover.SetImageResource(Resource.Drawable.kitzurTHM);
        mBooks.Add(new Book() { Title = "קיצור תורת המחנה - הלכות יום ויום ושבת", Cover = cover, imageResourceId = Resource.Drawable.kitzurTHM, Content = "KitzurTHM/KitzurTHMFull.html" });

        cover = new ImageView(Activity);
        ImageView newCover = new ImageView(Activity);
        newCover.SetImageResource(Resource.Drawable.halkasPurim);
        mBooks.Add(new Book() { Title = "הלכה כסדרה - הלכות פורים", Cover = newCover, imageResourceId = Resource.Drawable.halkasPurim });

        cover = new ImageView(Activity);
        cover.SetImageResource(Resource.Drawable.halkasPesach);
        mBooks.Add(new Book() { Title = "הלכה כסדרה - הלכות פסח", Cover = cover, imageResourceId= Resource.Drawable.halkasPesach });

        cover = new ImageView(Activity);
        cover.SetImageResource(Resource.Drawable.netzach);
        mBooks.Add(new Book() { Title = "שו\"ת נצח יהודה", Cover = cover , imageResourceId = Resource.Drawable.netzach});

        cover = new ImageView(Activity);
        cover.SetImageResource(Resource.Drawable.tankim);
        mBooks.Add(new Book() { Title = "טיפול בטנקים בשבת", Cover = cover , imageResourceId = Resource.Drawable.tankim});

        cover = new ImageView(Activity);
        cover.SetImageResource(Resource.Drawable.tipulBeChalalim);
        mBooks.Add(new Book() { Title = "טיפול בחללים בשבת", Cover = cover , imageResourceId = Resource.Drawable.tipulBeChalalim, Content = "TipulBechalalimShabbat.html" });

        Refresh();
        return view;

    }

HalachotFragment 解析一个文档，这也使得它需要很长时间。

Answer 1

您现在可以在主活动中使用 ProgressBar 并将 Progressbar 对象设为静态，只要您更改片段显示该进度条并且当您的片段加载时隐藏该进度条。

Answer 2

每当 Fragment 发生变化时，尝试runOnUiThread 作为以下代码，

runOnUiThread(new Runnable() {

    @Override
    public void run() {
        // TODO Auto-generated method stub

        ProgressDialog pd = new ProgressDialog(Activity.this);
        pd.setMessage("Testing...");
        pd.show();

    }
}); 

如果你想隐藏ProgressDialog 表示使用，

pd.hide();

希望这对你有帮助。

Answer 3

首先你需要发布一些代码。

如何在片段加载时显示 ProgressBar？

当您从活动中调用片段时，将调用片段的onAttach() 方法。因此，那时您需要在该方法中获取您的活动对象引用。喜欢，

MainActivity mainActivity; // this should be global
@Override
public void onAttach(Activity activity) {
    // TODO Auto-generated method stub
    super.onAttach(activity);
    mainActivity = (MainActivity)activity;
}

因此，使用活动对象，您可以访问进度条对象并将其隐藏在 setUserVisibleHint() 方法中，在该方法中片段将被完全加载。

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    // TODO Auto-generated method stub
    super.setUserVisibleHint(isVisibleToUser);

    if (isVisibleToUser) {
      // hide progress bar
    }
}