我正在创建一个应用，主要活动的tablayout连接到一个viewpager。这个viewpager有三个片段。
我知道viewpager适配器管理3个片段（正确的数量）因为我使用了Logging语句。此外，我使用asyncTasks将数据加载到片段中，并且正确完成。加载数据后，它会填充Recyclerview。我使用了日志语句，我知道每个片段都有一个包含20个条目的recyclelerview，这是正确的。
但由于某种原因，我的viewpager不会显示片段，即使我在其上调用getItemCount（）时，我也会得到正确数量的片段。
你能帮我弄清楚为什么片段被创建但没有显示出来吗？
谢谢。
这是我的MainActivity：
public class MovieListActivity extends AppCompatActivity {
public static final String POPULAR = "popular";
public static final String TOP = "top";
public static final String FAVORITES = "favorites";
private static final String QUERY_TYPE = "query type";
private RecyclerView mRecyclerView;
/**
* Whether or not the activity is in two-pane mode, i.e. running on a tablet
* device.
*/
private boolean mTwoPane;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_movie_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
toolbar.setTitle(getTitle());
setupTabLayout();
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
if (findViewById(R.id.movie_detail_container) != null) {
// The detail container view will be present only in the
// large-screen layouts (res/values-w900dp).
// If this view is present, then the
// activity should be in two-pane mode.
mTwoPane = true;
}
}
private void setupTabLayout() {
TabLayout tabLayout = (TabLayout) findViewById(R.id.tablayout);
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
tabLayout.addTab(tabLayout.newTab().setText(POPULAR));
tabLayout.addTab(tabLayout.newTab().setText(TOP));
tabLayout.addTab(tabLayout.newTab().setText(FAVORITES));
List<Fragment> fragments = new ArrayList<>();
for (int i=0;i<3;i++) {
Bundle bundle = new Bundle();
bundle.putInt(QUERY_TYPE, i);
fragments.add(ListFragment
.instantiate(this,ListFragment.class.getName(),bundle));
}
viewPager.setAdapter(new MoviePagerAdapter(getSupportFragmentManager(), fragments));
tabLayout.setupWithViewPager(viewPager);
}
}
这是viewpager应该实例化3次的片段：
public class ListFragment extends Fragment {
private static final String QUERY_TYPE = "query type";
public static final int POPULAR = 0;
public static final int HIGHEST_RATED = 1;
public static final int FAVORITES = 2;
private RecyclerView mRecyclerView;
private int mListType;
public ListFragment() {}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
mListType = this.getArguments().getInt(QUERY_TYPE);
super.onCreate(savedInstanceState);
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.movie_list,container,false);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.movie_list);
assert mRecyclerView != null;
setupRecyclerView(mRecyclerView);
if (mListType == HIGHEST_RATED || mListType == POPULAR) {
requestMovies();
}
return super.onCreateView(inflater, container, savedInstanceState);
}
private void setupRecyclerView(@NonNull RecyclerView recyclerView) {
recyclerView.setAdapter(new MovieAdapter(getActivity()));
}
void setMovies(Movie[] movies) {
MovieAdapter movieAdapter = (MovieAdapter)mRecyclerView.getAdapter();
movieAdapter.setMovies(movies);
movieAdapter.notifyDataSetChanged();
}
private void requestMovies() {
if (mRecyclerView.getAdapter().getItemCount() == 0) {
new FetchMoviesTask(this).execute(POPULAR);
}
}
}
寻呼机适配器：
public class MoviePagerAdapter extends FragmentStatePagerAdapter {
private List<Fragment> mFragments;
public MoviePagerAdapter(FragmentManager fm, List<Fragment> mFragments) {
super(fm);
this.mFragments = mFragments;
}
@Override
public Fragment getItem(int position) {
return this.mFragments.get(position);
}
@Override
public int getCount() {
return mFragments==null? 0 : mFragments.size();
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case ListFragment.POPULAR:
return MovieListActivity.POPULAR;
case ListFragment.HIGHEST_RATED:
return MovieListActivity.TOP;
case ListFragment.FAVORITES:
return MovieListActivity.FAVORITES;
default:
throw new IllegalArgumentException("Requesting a fragment that doesn't exist");
}
}
}
以防万一：这些是活动和片段的xml文件：
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".MovieListActivity">
<android.support.design.widget.AppBarLayout
android:id="@+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:popupTheme="@style/AppTheme.PopupOverlay" />
<android.support.design.widget.TabLayout
android:id="@+id/tablayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
</android.support.v4.view.ViewPager>
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="@dimen/fab_margin"
android:src="@android:drawable/ic_dialog_email" />
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/movie_list"
android:name="com.example.madelenko.app.moviegami.MovieListFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layoutManager="GridLayoutManager"
app:spanCount="2"
tools:context="com.example.madelenko.app.moviegami.MovieListActivity"
tools:listitem="@layout/movie_list_content" />
答案 0 :(得分：1)
返回你在Fragment中膨胀的视图，
@Nullable
@Override
public View onCreateView(LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.movie_list,container,false);
return rootView ;
}