Java ViewPager 中的 Recyclerviews

Recyclerviews in ViewPager

提问by tobs

I'm trying to get this working: I basically want two Recyclerviews in one ViewPager. I followed this Tutorial: http://android-java-development.blogspot.de/2012/05/system.html, but it doesn't seem to work. I looks like the view pager is empty and the recycler view doesn't show up.

我正在努力让这个工作：我基本上想要一个 ViewPager 中的两个 Recyclerviews。我跟着这个教程：http: //android-java-development.blogspot.de/2012/05/system.html，但它似乎不起作用。我看起来视图寻呼机是空的，回收器视图没有显示。

Here's my layout code:

这是我的布局代码：

<android.support.v4.widget.SwipeRefreshLayout
        android:id="@+id/pager_refresh_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingTop="@dimen/tab_height">

        <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/accent"/>
    </android.support.v4.widget.SwipeRefreshLayout>

And my PageAdapter:

还有我的 PageAdapter：

public class NewsPagerAdapter extends PagerAdapter {
    private Context context;
    private Vector<RecyclerView> recyclerViewList;
    private String[] titles;

    public NewsPagerAdapter(Context context, int titlesId) {
        this.context = context;
        this.recyclerViewList = new Vector<>();

        setTitles(titlesId);
    }

    public void add(RecyclerView recyclerView) {
        recyclerViewList.add(recyclerView);
    }

    public RecyclerView.Adapter getAdapterForViewAtIndex(int index) {
        return recyclerViewList.get(index).getAdapter();
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        container.addView(recyclerViewList.get(position),
                new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 100)
        );
        return container;
    }

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

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view.equals(object);
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return titles[position];
    }

    public void setTitles(int titles) {
        this.titles = context.getResources().getStringArray(titles);
    }
}

And my onCreatView method:

我的 onCreatView 方法：

GridLayoutManager layoutManager1 = new GridLayoutManager(getActivity(), getResources().getInteger(R.integer.news_column_count));

GridLayoutManager layoutManager2 = new GridLayoutManager(getActivity(), getResources().getInteger(R.integer.news_column_count));

RecyclerView listView1 = new RecyclerView(getActivity());
RecyclerView listView2 = new RecyclerView(getActivity());
listView1.setLayoutManager(layoutManager1);
listView2.setLayoutManager(layoutManager2);

NewsAdapter adapter1 = new NewsAdapter(getActivity(), null);
NewsAdapter adapter2 = new NewsAdapter(getActivity(), null);
adapter1.setOnItemClickListener(this);
adapter2.setOnItemClickListener(this);

listView1.setAdapter(adapter1);
listView2.setAdapter(adapter2);

newsPagerAdapter.add(listView1);
newsPagerAdapter.add(listView2);

newsViewPager.setAdapter(newsPagerAdapter);

Here I'm passing the cursor object to the adapter:

在这里，我将游标对象传递给适配器：

@Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        ((NewsAdapter) newsPagerAdapter.getAdapterForViewAtIndex(0)).swapCursor(data);
    }

采纳答案by Клаус Шварц

You have to extend FragmentPagerAdapteror FragmentStatePagerAdapterin order to easily embed RecyclerView. If you are going to update your ViewPager contents during its lifecycle it is strictly recommended to use FragmentStatePagerAdapter

您必须扩展FragmentPagerAdapter或FragmentStatePagerAdapter为了轻松嵌入 RecyclerView。如果您要在其生命周期内更新 ViewPager 内容，则严格建议使用FragmentStatePagerAdapter

You will have to create additional fragment layout, containing RecyclerView.

您将不得不创建额外的片段布局，包含RecyclerView.

If you wish to update your ViewPagerwith SwipeRefreshLayout, don't wrap it with SwipeRefreshLayout. Instead, you must have SwipeRefreshLayoutinside fragment layout.

如果你想用 更新你ViewPager的SwipeRefreshLayout，不要用 包装它SwipeRefreshLayout。相反，您必须具有SwipeRefreshLayout内部片段布局。

Therefore for your fragment you may get the following xml:

因此，对于您的片段，您可能会得到以下 xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/listRefresh"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/categoryList"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</android.support.v4.widget.SwipeRefreshLayout>

And create additional Fragment class, which will inflate that layout and implement methods, that you will need to update refresh indicator status.

并创建额外的 Fragment 类，该类将扩充该布局并实现方法，您将需要更新刷新指示器状态。

A bit old example is found here: http://developer.android.com/training/implementing-navigation/lateral.html

一个有点老的例子在这里找到：http: //developer.android.com/training/implementing-navigation/lateral.html

If you wish to connect your ViewPager with new support library TabLayout, it is easily one with:

如果您希望将 ViewPager 与新的支持库 TabLayout 连接起来，它很容易与：

tabLayout.setupWithViewPager(viewPager);

Finally, if you will update your "fragmented" ViewPager, don't try to reset the adapter, as fragments are managed not with adapter, but with FragmentManager. It is wiser to update content of corresponding RecyclerViews

最后，如果您要更新“fragmented” ViewPager，请不要尝试重置适配器，因为碎片不是使用适配器管理的，而是使用FragmentManager. 更新相应的内容是明智的RecyclerViews

public class MyFragmentedPagerAdapter extends FragmentStatePagerAdapter {
    private final TabLayout mTabLayout;
    private final SwipeRefreshLayout.OnRefreshListener mRefreshListener;
    private Vector<PriceListFragment> fragmentList;
    private Vector<String> titles;

    public MyFragmentedPagerAdapter(FragmentManager fm, MyComplexData data, OnCartActionListener listener, TabLayout tabLayout, SwipeRefreshLayout.OnRefreshListener refreshListener) {
        super(fm);
        mTabLayout = tabLayout;

        // external refresh listener, that will trigger an updateData() 
        mRefreshListener = refreshListener;

        fragmentList = new Vector<>();
        titles = new Vector<>();
        updateData(data);
    }

    public void updateData(MyComplexData data) {
        boolean updateTabs = false;
        boolean hasNewData = false;

        Vector<String> newTitles = new Vector<>();

        int position = 0;
        for(TabContents tabContents : data.getTabContents()) {

            if(tabContents.getListContents() == null)
                continue;
            hasNewData = true;
            boolean isNewFragment;

            MyFragment fragment;
            try {
                fragment = fragmentList.get(position);
                isNewFragment = false;
            } catch (ArrayIndexOutOfBoundsException e) {
                fragment = new MyFragment();
                isNewFragment = true;
            }
            // Update the data, title and hide update indicator of SwipeRefreshLayout
            fragment.setTabContents(tabContents);

            newTitles.add(tabContents.getName());

            if(isNewFragment) {
                fragment.setRefreshListener(mRefreshListener);
                fragmentList.add(fragment);
            }
            position++;
        }

        if(!hasNewData)
            return;

        // we need to decide, whether to update tabs
        if(titles.size() != newTitles.size()) {
            updateTabs = true;
        } else {
            for(position = 0; position < titles.size(); position++) {
                if(!titles.get(position).equals(newTitles.get(position))) {
                    updateTabs = true;
                    break;
                }
            }
        }

        titles = newTitles;
        notifyDataSetChanged();

        if(updateTabs)
            mTabLayout.setTabsFromPagerAdapter(this);
    }

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

    // You need to override this method as well
    @Override
    public int getItemPosition(Object object) {
        MyFragment fragment = (MyFragment) object;
        String title = (String) fragment.getTitle();
        int position = titles.indexOf(title);

        if (position >= 0) {
            return position;
        } else {
            return POSITION_NONE;
        }
    }

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

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

Your MyFragmentclass has to implement getTitle()method.

你的MyFragment类必须实现getTitle()方法。