删除RecyclerView FooterView [英] Remove RecyclerView FooterView
本文介绍了删除RecyclerView FooterView的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在从外部数据库下载数据，并在用户向下滚动时填充数组.下载数据时，我正在显示一个footerview(loadmoreview).我目前停留在的地方是，当用户到达列表的末尾时，也就删除了此脚注视图，也就没有更多数据可供下载.
I'm downloading data from an external db and populate arrays when the user scrolls down. I'm showing a footerview (loadmoreview) while the data is being downloaded. Where I'm currently stuck at is removing this footerview when the user got to the end of the list aka there is no more data to download.
下载:
private void DownloadUsersClassic(final String start, final String finish) {
loadingMore = true;
Log.i("DownloadUsersClassic", "started");
StringRequest postReq = new StringRequest(Request.Method.POST, download_leaderboard_classic, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
if (response.length() > 10) {
//populate arrays from json
if (arr_userid.size() < 14) {
//set adapter the first time the user scrolls
mAdapter = new CustomAdapter(getActivity(), arr_userid, arr_username, arr_photo, arr_level, arr_date, true);
rv.setAdapter(mAdapter);
} else {
//call notifyDataSetChanged() at the other scrolls
mAdapter.notifyDataSetChanged();
}
else {
//there is no more data to download
mAdapter = new CustomAdapter(getActivity(), arr_userid, arr_username, arr_photo, arr_level, arr_date, false);
mAdapter.notifyDataSetChanged();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.i("VOLLEY_ERROR", error.toString());
}
}) {
@Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
params.put("start", start);
params.put("finish", finish);
return params;
}
};
适配器:
public class CustomAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
ArrayList<String> arr_userid = new ArrayList<String>();
ArrayList<String> arr_username = new ArrayList<String>();
ArrayList<String> arr_photo = new ArrayList<String>();
ArrayList<String> arr_level = new ArrayList<String>();
ArrayList<String> arr_date = new ArrayList<String>();
boolean show_footer;
public LayoutInflater inflater;
public static final int TYPE_ITEM = 1;
public static final int TYPE_FOOTER = 2;
Context context;
public CustomAdapter(Context context, ArrayList<String> arr_userid, ArrayList<String> arr_username, ArrayList<String> arr_photo, ArrayList<String> arr_level, ArrayList<String> arr_date, boolean show_footer) {
super();
this.arr_userid = arr_userid;
this.arr_username = arr_username;
this.arr_photo = arr_photo;
this.arr_level = arr_level;
this.arr_date = arr_date;
this.show_footer = show_footer;
this.inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public class GenericViewHolder extends RecyclerView.ViewHolder {
public TextView txtName, txtPoints, txtDate;
public ImageView ivUser;
public LinearLayout llLoadmore;
public GenericViewHolder(View v) {
super(v);
txtName = (TextView) v.findViewById(R.id.txtName);
txtPoints = (TextView) v.findViewById(R.id.txtPoints);
txtDate = (TextView) v.findViewById(R.id.txtDate);
ivUser = (ImageView) v.findViewById(R.id.ivUser);
llLoadmore = (LinearLayout) v.findViewById(R.id.loadmore);
}
}
class FooterViewHolder extends RecyclerView.ViewHolder {
TextView tvloadmore;
public FooterViewHolder (View itemView) {
super (itemView);
this.tvloadmore = (TextView) itemView.findViewById (R.id.tvloadmore);
}
}
public void add(int position, String item) {
arr_userid.add(position, item);
notifyItemInserted(position);
}
public void remove(String item) {
int position = arr_userid.indexOf(item);
arr_userid.remove(position);
notifyItemRemoved(position);
}
public CustomAdapter(ArrayList<String> myDataset) {
arr_userid = myDataset;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder (ViewGroup parent, int viewType) {
if(viewType == TYPE_FOOTER) {
View v = LayoutInflater.from (parent.getContext ()).inflate (R.layout.loadmore, parent, false);
return new FooterViewHolder (v);
} else if(viewType == TYPE_ITEM) {
View v = LayoutInflater.from (parent.getContext ()).inflate (R.layout.leaderboard_row, parent, false);
return new GenericViewHolder (v);
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if(holder instanceof FooterViewHolder) {
FooterViewHolder footerHolder = (FooterViewHolder) holder;
footerHolder.tvloadmore.setText("Footer");
footerHolder.tvloadmore.setOnClickListener (new View.OnClickListener () {
@Override
public void onClick (View view) {
Toast.makeText (getActivity(), "Clicked Footer", Toast.LENGTH_SHORT).show ();
}
});
} else if(holder instanceof GenericViewHolder) {
GenericViewHolder genericViewHolder = (GenericViewHolder) holder;
final String name = arr_username.get(position);
genericViewHolder.txtName.setText(arr_username.get(position));
genericViewHolder.txtPoints.setText(arr_level.get(position) + " Levels");
String year = arr_date.get(position).substring(0, 4);
String month = arr_date.get(position).substring(5, 7);
String day = arr_date.get(position).substring(8, 10);
genericViewHolder.txtDate.setText(month + "." + day + "." + year);
if (!arr_photo.get(position).equals("")) {
Picasso.with(getActivity())
.load(arr_photo.get(position))
.into(genericViewHolder.ivUser);
} else {
genericViewHolder.ivUser.setImageDrawable(null);
}
}
}
@Override
public int getItemCount() {
if (show_footer) {
return arr_userid.size() + 1; //+1 is for the footer as it's an extra item
} else {
return arr_userid.size();
}
}
@Override
public int getItemViewType (int position) {
if (show_footer) {
if (isPositionFooter(position)) {
return TYPE_FOOTER;
}
return TYPE_ITEM;
} else {
return TYPE_ITEM;
}
}
private boolean isPositionFooter (int position) {
return position == arr_userid.size ();
}
}
onScrollListener :
rv.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
visibleItemCount = rv.getChildCount();
totalItemCount = llm.getItemCount();
firstVisibleItem = llm.findFirstVisibleItemPosition();
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
// End has been reached
//we need the -1 otherwise 1 item will be missed the first time we scroll. I don't know why only the first
//time but the point it's working this way
DownloadUsersClassic(String.valueOf(totalItemCount-1), String.valueOf(num_loadfinish));
loading = true;
}
}
});
看到适配器末尾的布尔变量?我试图用它来告诉适配器我是否需要页脚. 下载数据时确实如此:
See the boolean variable at the end of the adapter? I'm trying to use it to tell the adapter whether I need the footer or I don't. It's true when I'm downloading data:
mAdapter = new CustomAdapter(getActivity(), arr_userid, arr_username, arr_photo, arr_level, arr_date, true);
到达终点时是错误的:
mAdapter = new CustomAdapter(getActivity(), arr_userid, arr_username, arr_photo, arr_level, arr_date, false);
问题是，什么都没有发生.页脚留在那里.我不能打电话
The thing is, nothing happens. The footer stays there. I can't call
mAdapter = new CustomAdapter(getActivity(), arr_userid, arr_username, arr_photo, arr_level, arr_date, false);
rv.setAdapter(mAdapter);
因为它重新初始化了适配器，并且它跳到了顶部.
because it reinitializes the adapter and it jumps to the top.
推荐答案
几个小时后，我发现了它. 在确定没有更多数据可下载的地方，添加:
After a few hours I found it out. Where you determine that there is no more data to download, add:
mAdapter.hideFooter();
mAdapter.notifyDataSetChanged();
将此添加到适配器:
public void hideFooter() {
show_footer = false;
}
这告诉适配器在末尾隐藏页脚.
This tells the adapter to hide the footer at the end.
查看本教程以获取完整代码.
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