滚动时重复使用视图时，在RecyclerView中选择的项目的保存状态 [英] Save state of the item selected in RecyclerView when view is reused while scrolling

问题描述

我为recyclerView创建了一个Adapter和ViewHolder.我在Viewholder中绑定itemView的imageButton.并在onBindViewHolder中设置了onClickListener.

I have created an Adapter and ViewHolder for the recyclerView. I bind the imageButton of the itemView inside the Viewholder. And have set an onClickListener inside the onBindViewHolder.

一切正常，但问题出在当我向下滚动列表时，imageButton的选定状态已更改为所选项目，并且列表底部的某些项目已经出现 已选择.

Everything works as expected but the issue is now when i scroll down the list the selected state of the imageButton changes for the selected item and some of the items on the bottom of the list already appear selected.

这是一些代码

public class ListViewHolder extends RecyclerView.ViewHolder {
    TextView textViewUserName;
    ImageButton imageButtonCheckMark;

    public ListViewHolder(View itemView) {
        super(itemView);
        textViewUserName = (TextView) itemView.findViewById(R.id.textView_user_name);
        imageButtonCheckMark = (ImageButton) itemView.findViewById(R.id.imageButton_add_user);
    }
}

适配器类

public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ListViewHolder> {

    private LayoutInflater inflater;
    private Context context;
    private List<Metadata> list;
    public static boolean isUserSelected = false;
    ListInterface listener;

    public ListAdapter(Context context, List<Metadata> data, ListInterface listener) {
        Log.d(TAG, "Passed list to adapter : " + data.size());
        inflater = LayoutInflater.from(context);
        this.context = context;
        this.list = data;
        this.listener = listener;
    }

    @Override
    public ListViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.item_following_people, parent, false);
        return new ListViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ListViewHolder holder, int position) {

        holder.textViewUserName.setText(list.get(position).name);

        holder.imageButtonCheckMark.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!isUserSelected) {
                    holder.imageButtonCheckMark.setImageResource(R.drawable.checkmark_green);
                    isUserSelected = true;
                } else {
                    holder.imageButtonCheckMark.setImageResource(R.drawable.checkmark_grey);
                    isUserSelected = false;
                }
                listener.onUserSelected(isUserSelected, holder.getLayoutPosition());
            }
        });
    }


    @Override
    public int getItemCount() {
        return list.size();
    }
}

接口类

public interface ListInterface {
    public void onUserSelected(boolean userStatus, int listPosition);
}

活动内部的接口回调侦听器

Interface callback listener inside activity

// Interface callback listener implemented in the activity class
private ArrayList<Metadata> metadataList = new ArrayList<>();
ArrayList<String> selectedUserIdList = new ArrayList<>();

@Override
public void onUserSelected(boolean isUserSelected, int pos) {
    if (isUserSelected) {
        Log.d(TAG, "Selected user Id: " + metadataList.get(pos).userID);
        followersSelectedIdList.add(metadataList.get(pos).userID);
    } else {
        Log.d(TAG, "Removed user Id: " + metadataList.get(pos).userID);
        followersSelectedIdList.remove(metadataList.get(pos).userID);
    }
}

推荐答案

您会看到此现象，因为在滚动时视图已被重用(回收).您需要保存列表中所有按钮的状态，并在onBindViewHolder()中的每个按钮可见时设置其状态.

You see this behavior because views are reused (recycled) as you scroll. You need to save the state for all buttons in the list and set the state on each button in onBindViewHolder() as it becomes visible.

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