android - 带 ViewPager 和 TabLayout 的抽屉导航 : Fragments not loaded properly

Question

我制作了一个示例项目，其中包含带滑动选项卡的抽屉导航。我使用了 android studio 中的 ViewPager、TabLayout 和 NavigationDrawer 模板。

问题是有时 fragment View 是可见的，但只要我选择不同的抽屉项目，对应于该 fragment 的 View 就会变得不可见，当我向后滑动选项卡时它会变得可见。 我使用了 'com.android.support:design:22.2.0' 支持库

详细代码如下:

swipe_tab.xml 文件

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <android.support.design.widget.TabLayout
            android:id="@+id/sliding_tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabMode="scrollable"
           />

        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="0px"
            android:layout_weight="1"
            android:background="@android:color/white" />

    </LinearLayout>

fragment_page.xml 文件

        <?xml version="1.0" encoding="utf-8"?>
        <TextView xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center" />

ViewPagerFragment.java

        public class ViewPagerFragment extends Fragment {

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

                View view=inflater.inflate(R.layout.swipe_tabs,container,false);
                ViewPager viewPager = (ViewPager)view. findViewById(R.id.viewpager);
                viewPager.setAdapter(new SampleFragmentPagerAdapter(getFragmentManager(),getActivity()));

                // Give the TabLayout the ViewPager
                TabLayout tabLayout = (TabLayout) view.findViewById(R.id.sliding_tabs);
                tabLayout.setupWithViewPager(viewPager);
                return view;
            }
            public static ViewPagerFragment newInstance(int sectionNumber) {
                ViewPagerFragment fragment = new ViewPagerFragment();
                /*Bundle args = new Bundle();
                args.putInt(ARG_SECTION_NUMBER, sectionNumber);
                fragment.setArguments(args);*/
                return fragment;
            }
        }

PageFragment.java

        public class PageFragment extends Fragment {
            public static final String ARG_PAGE = "ARG_PAGE";

            private int mPage;

            public static PageFragment newInstance(int page) {
                Bundle args = new Bundle();
                args.putInt(ARG_PAGE, page);
                PageFragment fragment = new PageFragment();
                fragment.setArguments(args);
                return fragment;
            }

            @Override
            public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                mPage = getArguments().getInt(ARG_PAGE);
            }

            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
                View view = inflater.inflate(R.layout.fragment_page, container, false);
                TextView textView = (TextView) view;
                textView.setText("Fragment #" + mPage);
                return view;
            }
        } 

SampleFragmentPagerAdapter.java

        public class SampleFragmentPagerAdapter extends FragmentPagerAdapter {
            final int PAGE_COUNT = 10;
            private String tabTitles[] = new String[] { "Tab1", "Tab2", "Tab3" ,"Tab4","Tab5","Tab6","Tab7" ,"Tab8","Tab9","Tab10"};
            private Context context;

            public SampleFragmentPagerAdapter(FragmentManager fm, Context context) {
                super(fm);
                this.context = context;
            }

            @Override
            public int getCount() {
                return PAGE_COUNT;
            }

            @Override
            public Fragment getItem(int position) {
                return PageFragment.newInstance(position + 1);
            }

            @Override
            public CharSequence getPageTitle(int position) {
                // Generate title based on item position
                return tabTitles[position];
            }
        }

MainActivity.java

**At last I made the following changes in the Navigation Drawer's template provided in the android studio**


 public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getSupportFragmentManager();
        switch (position) {
            case 0:

            fragmentManager.beginTransaction()
                    .replace(R.id.container, ViewPagerFragment.newInstance(position + 1))
                    .commit();
                break;

            default: fragmentManager.beginTransaction()
                    .replace(R.id.container, PlaceholderFragment.newInstance(position + 1))
                    .commit();
        }
    }

Answer 1

使用

viewPager.setAdapter(new SampleFragmentPagerAdapter(getChildFragmentManager(),getActivity())); 

代替

viewPager.setAdapter(new SampleFragmentPagerAdapter(getFragmentManager(),getActivity()));