在回收器视图中保留项目的状态

Question

我有一个从API填充数据的回收器视图。每行都有一个喜欢按钮，用户可以按下并更改图标的颜色。

当用户按下按钮时，它工作正常，但是当他向上滚动页面然后返回到喜欢的行时，喜欢消失了，看起来以前从未按下过。

如何保持这种"喜欢"状态？

public class SocialAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
...
public SocialAdapter(Context context, JSONArray pages){
mContext = context;
mPages = pages;
...
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.social_row, parent, false);
MyHolder holder=new MyHolder(view);
return holder;
}
@Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, int position) {
MyHolder myHolder= (MyHolder) holder;
try {
JSONObject mpackid = mPages.getJSONObject(position);
//myHolder.button_like.setText("Eu quero!");
myHolder.button_like.setEnabled(true);
myHolder.button_like.setBackground(mContext.getResources().getDrawable(R.drawable.empty_star));
myHolder.number_likes.setText(mpackid.optJSONObject("info").optString("likes")+" foo");
myHolder.number_likes.setTextColor(Color.parseColor("#525252"));
myHolder.user_name.setText(mpackid.optString("user_full_name"));
myHolder.user_text.setText(mpackid.optJSONObject("info").optString("text"));
myHolder.feed_id.setText(mpackid.optJSONObject("info").optString("feed_suggestion_id"));
myHolder.number_likes.setText(mpackid.optJSONObject("info").optString("likes")+" foo");
myHolder.like_int.setText(mpackid.optJSONObject("info").optString("likes"));
myHolder.tags.setText("#"+mpackid.optJSONObject("info").optJSONArray("tags").toString().replace("[", "").replace("]", "").replace(""",""));
myHolder.date.setText(mpackid.optJSONObject("info").optString("elapsed_time"));
String likes = mpackid.optJSONObject("info").optJSONArray("liked_by").toString().replace("[", "").replace("]", "").replace(""","");
if(likes.contains(mUserId)){
myHolder.button_like.setEnabled(false);
myHolder.button_like.setBackground(mContext.getResources().getDrawable(R.drawable.filled_star));
myHolder.number_likes.setText("foo "+mpackid.optJSONObject("info").optString("likes")+" foo");
myHolder.number_likes.setTextColor(Color.parseColor("#525252"));
}
Glide.with(mContext).load(mpackid.optString("user_avatar_url"))
.asBitmap()
.thumbnail(Glide.with(mContext).load(R.drawable.ajax_loader).asBitmap())
.fitCenter()
.into(myHolder.user_image);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public long getItemId(int position) {
return 0;// not using this
}
@Override
public int getItemCount() {
return mPages.length();
}

private static class ViewHolder{
ImageView icon;
TextView itemName;
TextView url;
}
class MyHolder extends RecyclerView.ViewHolder{
CircleImageView user_image;
TextView user_name;
TextView user_text;
TextView feed_id;
TextView number_likes;
TextView like_int;
TextView date;
TextView tags;
ImageButton button_like;
// create constructor to get widget reference
public MyHolder(View itemView) {
super(itemView);
user_image = (CircleImageView) itemView.findViewById(R.id.user_image);
user_name = (TextView) itemView.findViewById(R.id.user_name);
user_text = (TextView) itemView.findViewById(R.id.headline);
number_likes = (TextView) itemView.findViewById(R.id.number_likes);
feed_id = (TextView) itemView.findViewById(R.id._id);
like_int = (TextView) itemView.findViewById(R.id.likes_nb);
button_like = (ImageButton) itemView.findViewById(R.id.button5);
date = (TextView) itemView.findViewById(R.id.date);
tags = (TextView) itemView.findViewById(R.id.feed_tag);
}
}
public JSONObject getItem(int position) {
try {
return mPages.getJSONObject(position);
} catch (JSONException e) {
e.printStackTrace();
return null;
}
}
public void addMoreData(JSONArray loadMoreArray) throws JSONException {
//Seta data pra LoadArray
mPages.length();
this.mPages = mPages.put(loadMoreArray.getJSONObject(0));
notifyItemRangeInserted(mPages.length(), mPages.length()+1);
SmoothRecyclerView recyclerView = (SmoothRecyclerView) ((Activity) this.mContext).findViewById(R.id.chat_social);
recyclerView.scrollToPosition(mPages.length()-1);
}

Answer 1

你必须在 BindViewHolder 中使用 if else。

if(likes.contains(mUserId)){
myHolder.button_like.setEnabled(false);
myHolder.button_like.setBackground(mContext.getResources().getDrawable(R.drawable.filled_star));
myHolder.number_likes.setText("foo "+mpackid.optJSONObject("info").optString("likes")+" foo");
myHolder.number_likes.setTextColor(Color.parseColor("#525252"));
}
else{
//behaviour when like.contains(userId) is false.
}

这是因为视图持有者将在用户滚动时回收上一个项目的视图，因此您必须在这两种情况下使用 if else，以便视图持有者将按预期运行。