在基本适配器中滚动后，TextView 值变回以前的值

Question

我一直在研究这个问题，但找不到解决方案。关于我的自定义列表视图的所有内容似乎都正常运行。当我单击 holder.feedUpVoteButton 时，文本会正确更改 +=1。但是，当我向下滚动并向上滚动时，文本值将恢复为单击之前的值。

我拒绝使用 notifyDatasetChanged 因为我不会添加任何内容或从列表中删除任何内容。

public class CustomFeedListViewAdapter extends BaseAdapter{

    CustomFeedListViewAdapter customFeedListViewAdapter;
    Date createdAt, currentDate; int num;
    static HashMap<String, String> oneData = new HashMap<String, String>();
    HashMap<String, String> iFeed = new HashMap<>();


    private String likesString;

    String upVoteClicked, downVoteClicked;
    HashMap<String, String> mFeed = new HashMap<>();
    List<ParseObject>  mObjects;

    private ParseObject parseObFeed;

        CustomFeedListViewAdapter(Context context, ArrayList<HashMap<String, String>> data) {

        super();
        this.mContext = context;
        GlobalFeedTab.arrayFeedList = data;
        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }


    @Override
    public int getCount() {
        return GlobalFeedTab.arrayFeedList.size();
    }

    @Override
    public Object getItem(int i) {
        return GlobalFeedTab.arrayFeedList.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {

         likes = new int[GlobalFeedTab.arrayFeedList.size()];
         countryNames = new int[GlobalFeedTab.arrayFeedList.size()];
        dateNames = new String[GlobalFeedTab.arrayFeedList.size()];

       final ViewHolder holder;

        if (view == null) {

            position = i;

            view = inflater.inflate(R.layout.feed_list_row, viewGroup, false);

            holder = new ViewHolder();


            holder.feedNumOfLikes = (TextView) view.findViewById(R.id.feedNumofLikes);
            holder.feedUpVoteButton = (Button) view.findViewById(R.id.feedUpVoteButton);



        } else {
            position = i;
            holder = (ViewHolder) view.getTag();
        }


        mFeed = GlobalFeedTab.arrayFeedList.get(position);

        holder.feedNumOfLikes.setText(mFeed.get("likes"));

        likesString = mFeed.get("likes");
        likes[position] = Integer.valueOf(likesString);

        holder.feedUpVoteButton.setTag(position);

        ParseQuery<ParseObject> query2 = new ParseQuery<ParseObject>("FeedItem");
        query2.setLimit(250);
        query2.addDescendingOrder("createdAt");

        query2.findInBackground(new FindCallback<ParseObject>() {
            @Override
            public void done(final List<ParseObject> objects, ParseException e) {

                if (e == null) {

                    for ( final ParseObject object : objects) {



                        holder.feedUpVoteButton.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {

                                int pos = (Integer) v.getTag();
                                parseObFeed = objects.get(pos);
                                username = parseObFeed.getString("username");
                                createdAt = parseObFeed.getDate("createdAt");

                                likes[pos] += 1;                           
                                parseObFeed.put("likes", likes[pos]);
                                holder.feedNumOfLikes.setText(String.valueOf(parseObFeed.getInt("likes")));

                                parseObFeed.put(ParseUser.getCurrentUser().getUsername() + "upvoteClicked", true);

                                parseObFeed.saveInBackground();
                            }
                        });                

            }
        });


        return view;
    }


    private class ViewHolder {

        ImageView feedProfilePic;
        TextView feedUsername;
        TextView feedNumOfLikes;
        TextView feedFeedItem;
        TextView feedDate;
        TextView feedNumofReplies;
        Button feedUpVoteButton;
        Button feedDownVoteButton;
        Button feedCommentButton;
        ListView feedListView;

    }

}

Answer 1

实际上这就是整个 theory.When 你递增一个 value.You 必须递增列表中你从那里获取 data.Because 的值当你向下滚动时，上面的行将 lost.When 你向上滚动，列表将从列表中再次加载 values.So 你所要做的就是增加列表中的值，即 GlobalFeedTab.arrayFeedList link 是为了进一步的细节，对于任何寻找更多细节的人当你写这行时

likes[pos] += 1;

您还必须增加您的 arraylist(mFeed) 中的值，然后编写 notifyDataSetChanged()；

Answer 2

每次 getView 被调用，你重新制作

likes = new int[GlobalFeedTab.arrayFeedList.size()];

这不会在您滚动时保存，您单击的行离开并重新进入显示。持有者可以持有这个整数值。

private class ViewHolder {
    int likes;
    TextView feedNumOfLikes; 
}

并相应更新

holder.feedUpVoteButton
    .setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            holder.feedNumOfLikes.setText(String.valueOf(++holder.likes));

但是，您还需要更新解析对象。

parseObFeed.put("likes", holder.likes);
parseObFeed.saveInBackground();
// notifyDataSetChanged(); // Up to you. Might not work without

I refuse to use notifyDatasetChanged because I am not adding anything or removing anything from the list.

不过，您正在修改数据。调用它将使您的适配器数据与存储在 Parse Server 中的数据一致。

编辑

这变得很复杂，因为您要让每个 "row" 都有一些 "nested" 与之关联的对象列表。我想您可以将整个列表存储在容器中。

private class ViewHolder {
    // Java variables to hold onto
    int likes;
    List<ParseObject> feedItems = new ArrayList<ParseObject>();

    // Android views to bind those values to
    TextView feedNumOfLikes; 
}

在适配器内部时，您调用 Parse 以获取适配器中每个项目的次级列表，但您只需将其存储在容器中。当 query2 returns 时，不要用它做任何其他事情。

你真正的问题是不清楚 query2 甚至返回了什么。当然，这是一些数据列表，但您真的想在列表中显示列表吗？此外，适配器的每个项目都从 Parse 查询完全相同的数据。我认为您需要一个过滤器...然后，您的 position 变量在 GlobalFeedTab.arrayFeedList 和 List<ParseObject> 之间不对应，因为它们是不同的列表。

这里只是我可以指出的一些评论。

    else {
        holder = (ViewHolder) view.getTag();
    }

    // You don't need 'position', it is just the 'i' value...
    mFeed = GlobalFeedTab.arrayFeedList.get(i);

    // This is stored in the Activity, I guess? 
    likesString = mFeed.get("likes");
    holder.feedNumOfLikes.setText(likesString);

    holder.feedUpVoteButton.setTag(i);

    ParseQuery<ParseObject> query2 = new ParseQuery<ParseObject>("FeedItem");

    // This is getting some related "FeedItem" for the current row
    // Just store the info, don't do anything with it yet
    query2.findInBackground(new FindCallback<ParseObject>() {
        @Override
        public void done(final List<ParseObject> objects, ParseException e) {
            if (e == null) {
                holder.feedItems.clear();
                holder.feedItems.addAll(objects);
                notifyDataSetChanged();
            }
        } 
    };

    // Here, you can setup the button for the current row
    holder.feedUpVoteButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            int pos = (Integer) v.getTag();

            // This is wrong... 'pos' is the position of the adapter! Not the index of List<ParseObject> results from earlier
            // And this is a very clear ArrayIndexOutOfBounds error...
            // The adapter could be shorter/longer than the holder.feedItems
            parseObFeed = holder.feedItems.get(pos);

            // !! TODO: Figure out which parseObFeed you actually want to use here 

            username = parseObFeed.getString("username");
            createdAt = parseObFeed.getDate("createdAt");

            holder.likes++;
            parseObFeed.put("likes", holder.likes);

            // This is the value that "resets" when you scroll. 
            // parseObFeed has not yet been saved, so when you scroll, the data isn't changed. 
            holder.feedNumOfLikes
                 .setText(String.valueOf(parseObFeed.getInt("likes")));

            // Not really sure what this does - You can store an array of likes rather than one field per username
            parseObFeed.put(ParseUser.getCurrentUser().getUsername() + "upvoteClicked", true);

            parseObFeed.saveInBackground();
            notifyDataSetChanged();
        }
    });    
}

我不记得 saveInBackground 是否有回调，但这可能需要调查

Answer 3

经过不断的试错。我终于想出了如何在滚动后更改文本视图。我的问题是我得到了错误的 ParseObject 值。我的主 activity 包含一个 ParseQuery 并且我从 Hashmap(); 得到 likes 但是，由于某种原因我无法直接传递 likes 的值所以我传递了ParseObject 本身。因此，在我的 BaseAdapter Class 中不需要查询。然后，我在 GetView(); 中实现了这些代码行来回答我原来的问题：

   holder.upvote[position] =  holder.parseObList[position].getBoolean(ParseUser.getCurrentUser().getUsername() + "upvoteClicked");
    holder.downvote[position] =  holder.parseObList[position].getBoolean(ParseUser.getCurrentUser().getUsername() + "downvoteClicked");

    if(holder.upvote[position]  ){
        holder.feedUpVoteButton.setBackgroundResource(R.drawable.arrowclicked);
        holder.feedNumOfLikes.setText(String.valueOf(holder.likes[position]));

    }
    else if(!holder.upvote[position]){
        holder.feedUpVoteButton.setBackgroundResource(R.drawable.arrowunclicked);
        holder.feedNumOfLikes.setText(String.valueOf(holder.likes[position]));


    }
    if(holder.downvote[position]){
        holder.feedDownVoteButton.setBackgroundResource(R.drawable.arrowclicked);

    }
    else if(!holder.downvote[position]){
        holder.feedDownVoteButton.setBackgroundResource(R.drawable.arrowunclicked);

    }

在基本适配器中滚动后，TextView 值变回以前的值

TextView value changes back to previous value after scroll in base adapter

android

listview

baseadapter