Question

我有一个private _album: {src: string, caption: string, thumb: string}[] = // ..rest of the code，里面有两个标签。选项卡是“卡”和“收藏夹”卡。我在两个标签中都使用了相同的片段。该片段包含一个Viewpager，我会对其动态更新。我将元素逐个添加到两个选项卡。首先，我将元素完全添加到第二个选项卡（“最爱卡片”选项卡）中。我的问题是，当我将元素添加到第二个选项卡时，我在第一个选项卡中的RecyclerView也得到了更新。现在，第一个选项卡RecyclerView中的元素是现有元素加上我在第二个选项卡中添加的元素的总和。我在两个RecyclerView标签中都设置了两个不同的ArrayList。但是当ViewPager在第一个选项卡getItemCount()中调用时，ArrayList具有我在第二个选项卡中添加的元素。

我在两个选项卡中都使用带有RecyclerView的相同片段。当我想更新单个标签时，我在RecyclerView上调用notifyDatasetChanged()。因此，每次ViewPager都在片段中重新初始化。

这是我的Viewpager适配器

RecyclerView

}

这是我的卡片片段

public class ViewPagerWebCardsAdapter extends FragmentStatePagerAdapter {

private ArrayList<WebCardBaseResponseModel> webCardDetailList;
private ArrayList<WebCardBaseResponseModel> followingWebCardList;
private Context context;
private boolean isEmptyFavoriteWebcardList;
private boolean isEmptyWebcardsList;

public ViewPagerWebCardsAdapter(FragmentManager fm, ArrayList<WebCardBaseResponseModel> webCardDetailList,
                                ArrayList<WebCardBaseResponseModel> followingWebCardList,
                                Context context) {
    super(fm);
    this.webCardDetailList = webCardDetailList;
    this.followingWebCardList = followingWebCardList;
    this.context = context;
}

public void updateWebCardLists( ArrayList<WebCardBaseResponseModel> webCardDetailList,
                                ArrayList<WebCardBaseResponseModel> followingWebCardList) {
    this.webCardDetailList = webCardDetailList;
    this.followingWebCardList = followingWebCardList;
    notifyDataSetChanged();
}

public void setEmptyFollowingCardsFragment() {
    isEmptyFavoriteWebcardList = true;
    notifyDataSetChanged();
}

public void setEmptyWebCardsFragment() {
    isEmptyWebcardsList = true;
    notifyDataSetChanged();
}

@Override
public Fragment getItem(int position) {
    if(position == 0) {
        WebCardListFragment webCardListFragment = new WebCardListFragment();
        webCardListFragment.setWebCardDetailList(webCardDetailList);
        webCardListFragment.setEmptyListFragment(isEmptyWebcardsList);
        return webCardListFragment;
    } else {
        WebCardListFragment webCardListFragment = new WebCardListFragment();
        webCardListFragment.setWebCardDetailList(followingWebCardList);
        webCardListFragment.setEmptyListFragment(isEmptyFavoriteWebcardList);
        webCardListFragment.setAsFavoritesList();
        return webCardListFragment;
    }
}

@Override
public int getCount() {
    return Constants.NUMBER_TWO;
}

@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}

@Override
public CharSequence getPageTitle(int position) {
    if(position == 0) {
        return context.getString(R.string.webcards);
    } else {
        return context.getString(R.string.favorite);
    }
}

}

最后，这是我在片段内部使用的public class WebCardListFragment extends Fragment { @BindView(R.id.web_card_recycler_view) RecyclerView mWebCardDetailRecyclerView; @BindView(R.id.tv_description) TextView tvDescription; @BindView(R.id.progress_bar) public ProgressBar progressBar; private WebCardListAdapter mWebCardListAdapter; ArrayList<WebCardBaseResponseModel> mWebCardDetailList; WebCardActivity activity; private boolean isFavorites; private boolean isEmptyListFragment; @Override public void onAttach(Context context) { super.onAttach(context); activity = (WebCardActivity) context; } @Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); } public void setWebCardDetailList(ArrayList<WebCardBaseResponseModel> mWebCardDetailList) { this.mWebCardDetailList = mWebCardDetailList; } public void setAsFavoritesList() { this.isFavorites = true; } @Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_webcard_list, container, false); ButterKnife.bind(this, view); initView(); return view; } private void initView() { if(isFavorites) { tvDescription.setText(getString(R.string.select_webcard_to_share)); } RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(activity); mWebCardDetailRecyclerView.setLayoutManager(mLayoutManager); mWebCardDetailRecyclerView.setHasFixedSize(true); mWebCardDetailRecyclerView.setItemAnimator(new DefaultItemAnimator()); if(mWebCardDetailList != null && mWebCardDetailList.size() > 0) { progressBar.setVisibility(View.GONE); tvDescription.setVisibility(View.VISIBLE); mWebCardListAdapter = new WebCardListAdapter(activity, mWebCardDetailList, isFavorites); } if(isEmptyListFragment) { progressBar.setVisibility(View.GONE); tvDescription.setVisibility(View.VISIBLE); tvDescription.setText(getString(R.string.no_webcards_to_list)); } mWebCardDetailRecyclerView.setAdapter(mWebCardListAdapter); } public void setEmptyListFragment(boolean isEmptyList) { isEmptyListFragment = isEmptyList; }适配器

RecyclerView

}

我希望两个标签中的public class WebCardListAdapter extends RecyclerView.Adapter<WebCardListAdapter.ViewHolder> { private Context mContext; private ArrayList<WebCardBaseResponseModel> mWebCardDetailList; private boolean isFavorites; public WebCardListAdapter(Context context, ArrayList<WebCardBaseResponseModel> webCardDetailList, boolean isFavorites) { mContext = context; mWebCardDetailList = webCardDetailList; this.isFavorites = isFavorites; } @NonNull @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_webcard_detail_layout, parent, false); return new ViewHolder(view); } @Override public void onBindViewHolder(final ViewHolder holder, final int position) { setListItemView(holder, position); setListItemClickListener(holder); } @Override public int getItemCount() { return mWebCardDetailList.size(); } @Override public long getItemId(int position) { return position; } @Override public int getItemViewType(int position) { return position; } class ViewHolder extends RecyclerView.ViewHolder { private TextView mCardNameTextView; private LinearLayout mWeCardLinearLayout; @BindView(R.id.tv_phone) TextView phone; ViewHolder(View itemView) { super(itemView); ButterKnife.bind(this, itemView); mCardNameTextView = (TextView) itemView.findViewById(R.id.webcard_name_textview); mWeCardLinearLayout = (LinearLayout) itemView.findViewById(R.id.wed_card_title_linear_layout); } }是独立的。当我将元素添加到第二个标签ListView时，该元素不应反映在第一个标签RecyclerView中。

Answer 1

基本区别

FragmentPagerAdapter

适用于有限（固定）数量的项目（片段）。为什么？因为它一旦创建就永远不会从FragmentManager中删除片段实例（除非Activity完成）。它仅将视图与当前不可见的片段分离。一旦无法访问片段，onDestroyView（）就会在您的片段上被调用，一旦您回到该片段，onCreateView（）将被调用。

FragmentStatePagerAdapter

FragmentStatePagerAdapter对内存的了解更多。一旦无法到达Fragment实例，它将完全从FragmentManager中删除它们。删除的Fragments的状态存储在FragmentStatePagerAdapter内部。返回到现有项目后，将重新创建Fragment实例，并恢复状态。该适配器适用于计数未知的列表或项目变化很大的列表。

因此FragmentPagerAdapter将解决此问题

我在视图寻呼机上调用notifyDatasetChanged（）。因此，每次碎片中的回收站视图都会重新初始化。

Answer 2

从vew寻呼机适配器类中删除替代函数“ getItemPosition”。希望对您有所帮助。

Answer 3

感谢您的回答，无论如何，此问题与Recyclerview或Viewpager无关，这是由于我对变量引用的误解而发生的。我在活动中的其他位置更改了ArrayList。这会影响recyclerview中的列表。

Viewpager内有多个Recyclerview的问题

3 个答案: