notifydataSetChanged 工作但仅在列表视图 Android 中显示 1 个结果 [英] notifydataSetChanged working but only showing 1 result in listview Android

问题描述

我有一个问题，当我调用 notifydataSetChanged 函数时只显示 1 个结果.我在这个论坛上读到需要清除Array列表，然后需要添加数据才能使notifydataSetChanged正常工作.我遵循了那个，但问题是当新数据到达时它会清除所有其他数据并且只显示列表中的最新项目.我知道这是一个 clear() 问题，但我不知道如何解决它.任何建议将不胜感激.

Hi i have an issue where only 1 result is being shown when i call a notifydataSetChanged function. I have read in this forum that the Array list needs to be cleared, then the data needs to be added for the notifydataSetChanged to work properly. I have followed that, but the problem is when the new data arrives it clears all the other data and only shows the latest item from the list. I know its a clear() issue, but i cant work out how to fix it. Any suggestions would be gratefully appreciated.

我的适配器:

public MessageAdapter(Activity context, ArrayList<ArrayList<ReadMessage>> list) {
    mContext = context;
    mList = list;
    mLayoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

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

@Override
public Object getItem(int pos) {
    return mList.get(pos);
}

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


@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View v = convertView;
    CompleteListViewHolder viewHolder;
    if (convertView == null) {
        LayoutInflater li = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = li.inflate(R.layout.list_row, null);
        viewHolder = new CompleteListViewHolder(v);
        v.setTag(viewHolder);
    } else {
        viewHolder = (CompleteListViewHolder) v.getTag();
    }
    viewHolder.messageText.setText(mList.get(position).get(position).getMessage());
    viewHolder.fromText.setText(mList.get(position).get(position).getSender());
    return v;
}

}

class CompleteListViewHolder {
    public TextView messageText;
    public TextView fromText;

public CompleteListViewHolder(View base) {
    messageText = (TextView) base.findViewById(R.id.message);
    fromText = (TextView) base.findViewById(R.id.user);
}

以下方法是我向列表中添加项目的地方:

The following method is where i am adding items to the list :

  private void addItemsToList() {
       sentMessages.clear();
         sentMessages.add(localstoragehandler.getUserComments(MessageService.USERNAME, friendUsername()));
      messageAdapter.notifyDataSetChanged();
}

当新数据从网络服务到达时调用 addItemsToList().

The addItemsToList() is called when new data arrives from the web service.

谢谢

推荐答案

可能发生的事情是你的列表 sentMessages 是你用来初始化你的 MessageAdapter 的，对吗?通过调用 mList.clear()，因为它指向与 sentMessages 相同的对象，您正在清除两个列表中的所有内容(这实际上只是完全相同的列表).我要做的是将您的 MessageAdapter 构造函数更改为以下内容:

What's probably happening is that your list sentMessages is what you used to initialize your MessageAdapter, correct? By calling mList.clear() since it points to the same object as sentMessages, you are clearing everything from both lists (which is really just the exact same list). What I would do is change your MessageAdapter constructor to the following:

public MessageAdapter(Activity context, ArrayList<ArrayList<ReadMessage>> list) {
    mContext = context;
    mList = new ArrayList<ArrayList<ReadMessage>>();
    mList.addAll(list);
    mLayoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

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