Tabclick监听器上的Viewpager更新

Question

我在第二个标签上的tabclick监听器上更新我的viewpager时出现问题＆＃34; CART＆＃34;，我想更新名为＆＃34; CART＆＃34;的第二个片段中的列表视图通过从数据库表中获取记录......

这是我在MainActivity中的代码：

tabLayout.setOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(viewPager){

        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            super.onTabSelected(tab);
            int tab_index = tab.getPosition();
            if (tab_index == 1){
                     adapter.updateData();
                  // adapter.notifyDataSetChanged();
                }

            }
        }`private void setupViewPager(ViewPager viewPager) {
    adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new OneFragment(), "HOME");
    adapter.addFragment(new TwoFragment(), "CART");
    viewPager.setAdapter(adapter);
}

class ViewPagerAdapter extends FragmentStatePagerAdapter {
    public final List<Fragment> mFragmentList = new ArrayList<>();
    public final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    public  void updateData(){
        notifyDataSetChanged();
    }

    @Override
    // Return the Fragment associated with a specified position..... Android calls getItem(...) only if it wants to create new Fragments.
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    //Return the number of views available.
    public int getCount() {
        return mFragmentList.size();
    }

    @Override
    // Called when the host view is attempting to determine if an item's position has changed.
    // Returns POSITION_UNCHANGED if the position of the given item has not changed or POSITION_NONE if the item is no longer present in the adapter.
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

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

}`

片段2中的代码，即CART：

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {

    DM = DB_Object.getInstance(getActivity());
    View view = inflater.inflate(R.layout.fragment_two,container,false);
    listview_product = (ListView) view.findViewById(R.id.product_list);
    BindListView(DM);
    return view;
}

public void set_order_set_id(boolean order,String id){ is_order = order; unique_id = id; }

public void BindListView(DataManipulator DM_Obj)
{
    BindProducts = new ArrayList<ProductList>();
    ProductDetails = new ArrayList<String[]>();
    ProductDetails = DM_Obj.GetFromInventory();

    product_barcode = new String[ProductDetails.size()];
    product_price = new String[ProductDetails.size()];

    int i = 0;
    for(String[] product : ProductDetails )
    {
        product_barcode[i] = product[0];
        product_price[i] = product[1];

        BindProducts.add(new ProductList(product_barcode[i],product_price[i]));
        i++;
    }

    if (getActivity() != null) {
        list_adapter = new ListAdapter(getActivity(), BindProducts);
       // listview_product = (ListView) getView().findViewById(R.id.product_list);
        listview_product.setAdapter(list_adapter);
        // listview_product.invalidate();
    }
}