查看寻呼机列表未刷新恢复

Question

在“我的片段”页面上，我添加了一个ViewPager，并在该ViewPager中加载了列表片段。第一次，它会正确加载列表，一旦导航到另一个片段，然后返回ViewPager内容（列表片段）不显示内容，它只会加载ViewPager标题，一旦更改标签会加载内容，这是我的代码，

首页片段

public class HomeFragment extends Fragment {
    @BindView(R.id.progressLayout)
    LinearLayout progressLayout;

    @BindView(R.id.tabLayout)
    TabLayout tabLayout;
    @BindView(R.id.viewpager)
    ViewPager viewpager;


    private static int pagePos = 0;
    ArrayList<Category> categories;
    CategoryPagerAdapter catrgoryAdapter;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_home, container, false);
        getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
        ButterKnife.bind(this, rootView);

        categories = getProductCategories();
        setupViewPager();
        tabLayout.setupWithViewPager(viewpager);

        return rootView;
    }

    @Override
    public void onResume() {
        super.onResume();
        getActivity().setTitle(null);
        catrgoryAdapter.notifyDataSetChanged();
    }


    private ArrayList<Category> getProductCategories() {
        categories = new ArrayList<Category>();
        categories.add(new Category(1, "Evening Dresses"));
        categories.add(new Category(2, "Abaya"));
        categories.add(new Category(3, "Night Dresses"));
        categories.add(new Category(4, "Shirt"));
        return categories;
    }

    private void setupViewPager() {
        catrgoryAdapter = new CategoryPagerAdapter(getActivity(), getActivity().getSupportFragmentManager(), categories);
        viewpager.invalidate();
        viewpager.setAdapter(catrgoryAdapter);
        if (catrgoryAdapter.getCount() > pagePos)
            viewpager.setCurrentItem(pagePos);
        catrgoryAdapter.notifyDataSetChanged();
        viewpager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            }

            @Override
            public void onPageSelected(int position) {
                pagePos = position;
            }

            @Override
            public void onPageScrollStateChanged(int state) {
            }
        });
    }
}

页面视图适配器

public class CategoryPagerAdapter extends FragmentPagerAdapter {
    Context context;
    private ArrayList<Category> categories = new ArrayList<>();

    public CategoryPagerAdapter(Context context, FragmentManager fm, ArrayList<Category> categories) {
        super(fm);
        this.context = context;
        this.categories = categories;
    }

    @Override
    public Fragment getItem(int position) {
        return new ProductListingFragment(categories.get(position));
    }

    @Override
    public int getCount() {
        return categories.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return categories.get(position).getCategoryName();
    }

    public View getTabView(int position) {
        View tab = LayoutInflater.from(context).inflate(R.layout.category_tab_title_view, null);
        TextView txtTitle = (TextView) tab.findViewById(R.id.txtTitle);
        txtTitle.setText(getPageTitle(position));
        return tab;
    }

}

ProductListingFragment页面

public class ProductListingFragment extends Fragment implements ProductActionListener {
    @BindView(R.id.progressLayout)
    LinearLayout progressLayout;
    @BindView(R.id.recyclerView)
    RecyclerView recyclerView;
    @BindView(R.id.noResultTextView)
    TextView noResultTextView;


    Category category;
    ArrayList<Product> products;
    ProductListAdapter productsAdapter;
    GridLayoutManager layoutManager;

    public ProductListingFragment() {}

    @SuppressLint("ValidFragment")
    public ProductListingFragment(Category category) {
        this.category = category;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_product_listing, container, false);
        getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
        ButterKnife.bind(this, rootView);

        layoutManager = new GridLayoutManager(getActivity(), 2);
        recyclerView.setLayoutManager(layoutManager);
        products = getCategoryProducts();
        populateProductList();

        return rootView;
    }

    @Override
    public void onResume() {
        super.onResume();
        products = getCategoryProducts();
        populateProductList();
    }

    private ArrayList<Product> getCategoryProducts() {
        products = new ArrayList<>();
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 1)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 2)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 3)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 4)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 5)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 6)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 7)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 8)));
        products.add(new Product(Integer.parseInt(category.getCategoryId() + "" + 9)));
        return products;
    }


    private void populateProductList() {
        int scrollTo = 0;
        if (layoutManager != null)
            scrollTo = layoutManager.findFirstVisibleItemPosition();
        noResultTextView.setVisibility(View.GONE);
        recyclerView.setVisibility(View.VISIBLE);
        if (products != null && products.size() > 0) {
            productsAdapter = new ProductListAdapter(getActivity(), this, products);
            recyclerView.invalidate();
            recyclerView.setAdapter(productsAdapter);
            if (scrollTo > 0 && products.size() > scrollTo)
                recyclerView.scrollToPosition(scrollTo);
        } else {
            recyclerView.setVisibility(View.GONE);
            noResultTextView.setVisibility(View.VISIBLE);
        }
    }


    @Override
    public void ProductSelected(Product product) {
        toProductDetailsFragment();
    }

    @Override
    public void ProductAddedToFavourite(Product product) {
        AppController.getInstance().addRemoveFavourites(product);
        populateProductList();
    }

    @Override
    public void ProductAddedToCart(Product product) {

    }

    private void toProductDetailsFragment() {
        ProductDetailsFragment fragment = new ProductDetailsFragment();
        getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.contentView, fragment).addToBackStack(null).commitAllowingStateLoss();
    }
}