我试图在单击时更改ImageView（如按钮）的背景。但是，单击“赞”图标后背景会立即更改，然后立即刷新recyclerview并复制项目（使用默认图标）
我从类似问题的答案中尝试了以下方法：
1-向onBindViewHolder添加一些条件以识别喜欢的商品
2- postAdapter.setHasStableIds（true）
3-使用postAdapter.notifyItemChanged（position）
4-覆盖适配器类中的以下方法：
@Override
public long getItemId(int position) {
return position;
}
@Override
public int getItemViewType(int position) {
return position;
}
@Override
public void setHasStableIds(boolean hasStableIds) {
super.setHasStableIds(hasStableIds);
}
我分别尝试了上述每种方法，然后一次全部尝试，但是没有任何效果，问题仍然存在：/
代码很复杂，所以它们是相关的部分：
1-适配器类：
请注意，它具有一个接口和一个接口实例。该实例在内部ViewHolder类的likeImage.setOnClickListener中使用，该类也设置了clicked和clickedPositions；
public class PostRecyclerAdapter extends RecyclerView.Adapter<PostRecyclerAdapter.ViewHolder> {
public interface ClickListener{
public void click(View view, int position);
}
private ArrayList<Post> postList;
private Context context;
private ClickListener clickListener;
private int clickedItemPosition = -1;
private boolean clicked = false;
public PostRecyclerAdapter(Context context, ArrayList<Post> postList){
this.context = context;
this.postList = postList;
}
public void onClickListener(ClickListener clickListener){
this.clickListener = clickListener;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
return new ViewHolder(LayoutInflater.from(context).inflate(R.layout.post_item, parent, false));
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
if(clicked){
if(clickedItemPosition == position){
holder.likeImage.setBackgroundResource(R.drawable.like_filled);
clicked = false;
return;
}
}
if(!clicked) {
Post post = postList.get(position);
holder.username.setText(post.getUsername());
holder.date.setText(post.getDateAdded().toString());
holder.description.setText(post.getDescription());
holder.likeNum.setText(String.valueOf(post.getLikeNum()));
holder.commentNum.setText(String.valueOf(post.getCommentNum()));
Picasso.get()
.load(Uri.parse(post.getImageUri()))
.placeholder(R.drawable.download)
.into(holder.postImage);
// holder.userImage.setText(post.getDateAdded().toString());
// holder.postImage.setText(post.getDateAdded().toString());
}
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public int getItemViewType(int position) {
return position;
}
@Override
public void setHasStableIds(boolean hasStableIds) {
super.setHasStableIds(hasStableIds);
}
@Override
public int getItemCount() {
if(postList != null)
return postList.size();
return 0;
}
// Inner View class
class ViewHolder extends RecyclerView.ViewHolder{
ImageView userImage, postImage, commentImage, likeImage ;
TextView username, date, description, commentNum, likeNum;
public ViewHolder(@NonNull View itemView) {
super(itemView);
userImage = itemView.findViewById(R.id.post_item_userImage);
username = itemView.findViewById(R.id.post_item_username);
date = itemView.findViewById(R.id.post_item_date);
postImage = itemView.findViewById(R.id.post_item_postImage);
likeNum= itemView.findViewById(R.id.post_item_likesNum);
commentNum = itemView.findViewById(R.id.post_item_commentsNum);
description = itemView.findViewById(R.id.post_item_description);
commentImage = itemView.findViewById(R.id.post_item_comments);
likeImage = itemView.findViewById(R.id.post_item_likes);
commentImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(context, "commentClicked", Toast.LENGTH_SHORT).show();
if(clickListener != null) {
clickedItemPosition = getAdapterPosition();
clickListener.click(view, getAdapterPosition());
}
}
});
likeImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(context, "LikeClicked", Toast.LENGTH_SHORT).show();
if(clickListener != null) {
clicked = true;
clickedItemPosition = getAdapterPosition();
clickListener.click(view, getAdapterPosition());
}
}
});
}
}
}
2-实现了onClickListener接口方法的地方：
@Override
public void click(View view, int position) {
switch(view.getId()){
case R.id.post_item_likes:
likeUnlike(view, position);
break;
case R.id.post_item_comments:
break;
}
3-在likeUnlike方法中，我尝试更改图标：
view.setBackgroundResource(R.drawable.like_filled);
postAdapter.notifyItemChanged(position);
这是完整的likeUnlike方法：
postCommentReference.whereEqualTo("userID", user.getUid())
.addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(@javax.annotation.Nullable QuerySnapshot queryDocumentSnapshots, @javax.annotation.Nullable FirebaseFirestoreException e) {
// within the comment sub-collection of the clicked post
if(e != null){
Toast.makeText(getContext(), "Exception "+e.toString() , Toast.LENGTH_SHORT).show();
}else{
if(queryDocumentSnapshots.isEmpty()){
// create a DOCUMENT for the comment:
DocumentReference likeDocReference = postCommentReference.document(user.getUid());
// create new like
Like like = new Like();
like.setPostID(post.getPostID());
like.setUserID(user.getUid());
like.setUsername(UserUtils.getInstance().username);
like.setLikeID(likeDocReference.getId());
// add like to db
likeDocReference.set(like);
//increment LikeNum
post.setLikeNum(post.getLikeNum()+1);
postReference.document(post.getPostID()).update("likeNum", post.getLikeNum())
.addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if(task.isSuccessful()){
Log.d("home_fragment_likeNum", "onComplete: likeNum is updated");
}else{
Log.d("home_fragment_likeNum", "onComplete: Exception: "+task.getException());
}
}
});
// change icon
view.setBackgroundResource(R.drawable.like_filled);
postAdapter.notifyItemChanged(position);
return;
}else{
}
}
}
});}