Question

我正试图通过每个路线应用程序的小步行时间进入Android应用程序开发但是有一点小故障阻止我继续下去我试图谷歌多次没有结果，这就是事情：

RecyclerView onClick-expand cards onBindViewHolder，一旦我添加太多项目，就会显示重新加载整个列表的奇怪行为。它也会以某种方式将整个列表移动一秒钟。作为参考，这是我的github项目：https://github.com/TheInsayn/velocity

以下是它应该如何表现：
Imgur

但是在我添加了第6个项目后，它的行为如下：

Imgur

以下是我用于适配器的代码（特别是isExpanded与class RecyclerAdapterWalks extends RecyclerView.Adapter<RecyclerAdapterWalks.WalkCardHolder> { private List<Walk> mWalkList; private RecyclerView mRecyclerView; private int mExpandedPosition = -1; class WalkCardHolder extends RecyclerView.ViewHolder { TextView mWalkRoute; TextView mWalkDuration; TextView mWalkDate; TextView mWalkWeekday; RelativeLayout mExpansion; TextView mAverageTime; WalkCardHolder(View view) { super(view); mWalkRoute = view.findViewById(R.id.txt_walk_route); mWalkDuration = view.findViewById(R.id.txt_walk_duration); mWalkDate = view.findViewById(R.id.txt_walk_date); mWalkWeekday = view.findViewById(R.id.txt_walk_weekday); mExpansion = view.findViewById(R.id.walk_card_expansion); mAverageTime = view.findViewById(R.id.txt_walk_average); } } RecyclerAdapterWalks(List<Walk> routes, RecyclerView rv) { mWalkList = routes; mRecyclerView = rv; setHasStableIds(true); } @Override public WalkCardHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_walk, parent, false); return new WalkCardHolder(view); } @Override public void onBindViewHolder(WalkCardHolder holder, int position) { Walk walk = mWalkList.get(position); holder.mWalkRoute.setText(walk.getRoute().getName()); holder.mWalkDuration.setText(DateFormat.format("mm:ss", new Date(walk.getDuration()))); holder.mWalkDate.setText(DateFormat.format("dd.MM.yyyy", walk.getDate())); holder.mWalkWeekday.setText(DateFormat.format("EEEE", walk.getDate())); //handle expansion in list final boolean isExpanded = position == mExpandedPosition; holder.mExpansion.setVisibility(isExpanded ? View.VISIBLE : View.GONE); holder.itemView.setActivated(isExpanded); holder.itemView.setOnClickListener(v -> { mExpandedPosition = isExpanded ? -1 : position; TransitionManager.beginDelayedTransition(mRecyclerView); notifyDataSetChanged(); }); if (isExpanded) { Date avg = new Date(walk.getRoute().getAverageWalkTime(mRecyclerView.getContext())); CharSequence min = DateFormat.format("m", avg); CharSequence sec = DateFormat.format("s", avg); String boldText = walk.getRoute().getName(); String timeStr = "average walk duration for " + boldText + ": "; if (!min.equals("0")) timeStr += min + "m and "; timeStr += sec + "s"; int idx = timeStr.indexOf(boldText); SpannableString str = new SpannableString(timeStr); str.setSpan(new StyleSpan(Typeface.BOLD), idx, idx + boldText.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE); holder.mAverageTime.setText(str); } } @Override public int getItemCount() { return mWalkList.size(); }）：
我甚至使用了来自I / O 2016的Google的参考建议。（我真的不想使用第三方库）

setHasStableIds(true)

我在RelativeLayout的FrameLayout中的CoordinatorLayout中的RecyclerView中有CardView ...

有人知道可能导致这种情况的原因吗？对不起，很长的帖子，谢谢你的帮助。：）

编辑：在Adapter的构造函数中使用CREATE TABLE SANORD ( ID INT, NAME VARCHAR2(20), ODATE DATE, CUST INT); Table created. INSERT INTO SANORD VALUES (90, 'SMITH','26-DEC-17',1002); 1 row created. INSERT INTO SANORD VALUES (135, 'JOHNSON','09-DEC-17',1002); 1 row created. INSERT INTO SANORD VALUES (235, 'JOHNSON','01-JAN-18',1002); 1 row created. INSERT INTO SANORD VALUES (322, 'JOHNSON','04-JAN-18',1002); 1 row created. COMMIT; SELECT id, name, odate, cust FROM sanord WHERE (name, odate) IN ( select name, max(odate) from sanord where cust = 1002 group by name) ; ID NAME ODATE CUST ---------- -------------------- --------- ---------- 90 SMITH 26-DEC-17 1002 322 JOHNSON 04-JAN-18 1002似乎有所帮助。但现在转型远非顺利小清单（更糟）：
Imgur
更长的清单（更好）：
Imgur

Answer 1

由于notifyDataSetChanged();行，它正在重新加载整个列表。这刷新了整个清单。如果您只添加了一个元素，我会建议使用notifyItemInserted(int position)，或者如果您要更新单个项目，那么只需使用函数notifyItemChanged(int position)

Answer 2

根据@napster的意见，我终于在一个老话题的帮助下解决了我的问题我非常信任来自I / O的Nick Butcher的例子引用：“这是一个可怕的解决方案” 使用https://stackoverflow.com/a/48092441/9165497中的技术一切都有所改善，我现在认为问题已经解决了。

现在我的代码看起来像这样，一切都更顺畅，没有问题：

final boolean isExpanded = position == mExpandedPosition;
holder.mExpansion.setVisibility(isExpanded ? View.VISIBLE : View.GONE);
holder.itemView.setActivated(isExpanded);
if (isExpanded) mPreviousExpandedPosition = holder.getAdapterPosition();
holder.itemView.setOnClickListener(v -> {
    mExpandedPosition = isExpanded ? -1 : holder.getAdapterPosition();
    notifyItemChanged(mPreviousExpandedPosition);
    notifyItemChanged(holder.getAdapterPosition());
});

使用RecyclerView和可扩展卡的奇怪故障

2 个答案: