应用程序在水平滚动时崩溃

Question

我正在创建一个Android应用，它在一个活动中包含一个带有多个片段的TabLayout。如果我的服务器中有可用的内容，则这些片段显示RecyclerView;如果没有内容，则显示EmptyView。

但是，如果我在活动标签中没有内容，如果我在标签之间横向滚动，则应用会崩溃。如果我在选项卡之间单击此导航，则不会发生此问题。我该如何解决？

我的代码是：

MessagesActivity.java：

.slick-slide
{
    height: 300px;
}

MessagesInboxTab.java :(目前所有标签都包含此类）

public class MessagesActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

private Toolbar toolbar;
private NavigationView navigationView;
private TabLayout tabLayout;
private ViewPager pager;
private FloatingActionButton newMessageButton;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.messagesactivity);

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    pager = (ViewPager) findViewById(R.id.messagesActivity_viewPager);
    setupViewPager(pager);

    tabLayout = (TabLayout) findViewById(R.id.messagesActivity_tabs);
    tabLayout.setupWithViewPager(pager);
    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            pager.setCurrentItem(tab.getPosition());
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {
        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {
        }
    });
}

private void setupViewPager(ViewPager viewPager) {
    MessagesTabAdapter adapter = new MessagesTabAdapter(getSupportFragmentManager());

    adapter.addFragment(new MessagesInboxTab(), getResources().getString(R.string.Inbox));
    adapter.addFragment(new MessagesSentTab(), getResources().getString(R.string.Sent));
    adapter.addFragment(new MessagesTrashTab(), getResources().getString(R.string.Trash));

    viewPager.setAdapter(adapter);
}

class MessagesTabAdapter extends FragmentPagerAdapter {

    private final List<Fragment> fragmentList = new ArrayList<>();
    private final List<String> fragmentTitleList = new ArrayList<>();

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

    @Override
    public Fragment getItem(int position) {
        return fragmentList.get(position);
    }

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

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

    public void addFragment(Fragment fragment, String title) {
        fragmentList.add(fragment);
        fragmentTitleList.add(title);
    }
}
}

片段的Xml：

public class MessagesInboxTab extends Fragment {
private RecyclerView recyclerView;
private ScrollView emptyView;
private ProgressBar progressView;
private ArrayList<MessageListItem> inboxList = new ArrayList<MessageListItem>();

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.list_tab, container, false);
    progressView = (ProgressBar) view.findViewById(R.id.progressBar_list);
    emptyView = (ScrollView) view.findViewById(R.id.emptyView_list);
    recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView_list);

    progressView.setVisibility(View.VISIBLE);

    getInbox();

    return view;
}

public void getInbox() {
    JsonObjectRequest jsonRequest = new JsonObjectRequest
            (Request.Method.GET, "http://my_domain.com/service/inbox", (String) null, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    //Check if there are messages

                    if (result!=null) { //There are messages
                        //Handle messages and store info in InboxList

                        final MessagesListItemAdapter adapter = new MessagesListItemAdapter(inboxList);
                        final LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
                        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);

                        recyclerView.setLayoutManager(layoutManager);
                        recyclerView.setHasFixedSize(true);
                        recyclerView.setAdapter(adapter);
                        recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL_LIST));
                        recyclerView.setItemAnimator(new DefaultItemAnimator());
                        adapter.notifyDataSetChanged();

                        progressView.setVisibility(View.GONE);
                        recyclerView.setVisibility(View.VISIBLE);
                    } else { //No messages
                        progressView.setVisibility(View.GONE);
                        emptyView.setVisibility(View.VISIBLE);
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    error.printStackTrace();
                }
            });

    Volley.newRequestQueue(getActivity()).add(jsonRequest);
}
}

最后，错误代码：

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

<ProgressBar
    android:id="@+id/progressBar_list"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="8dp"
    android:layout_centerInParent="true"
    style="?android:attr/progressBarStyleLarge" />

<LinearLayout
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recyclerView_list"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

        <ScrollView
            android:id="@+id/emptyView_list"
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingTop="93.3dp"
                android:paddingBottom="93.3dp"
                android:background="#000000" >

            </RelativeLayout>

        </ScrollView>

</LinearLayout>

</RelativeLayout>

Answer 1

将此添加到onCreateView()的{​​{1}}

Fragment

我认为这是因为当没有内容时你没有设置任何LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity()); layoutManager.setOrientation(LinearLayoutManager.VERTICAL); recyclerView.setLayoutManager(layoutManager); ，所以最好设置一个