即使在调用 notifydatasetchanged() 后，我的列表视图也没有更新

Question

我不知道为什么，但我的列表视图没有更新...我正在调用 notifyDataSetChanged() 并且我还尝试了他们要求这样做的另一个答案：

 private void editTransaction(int position) {
    h = historyItems.get(position);
    historyItems.remove(position);
    this.position = position;
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == 5 && resultCode == RESULT_OK) {
        String description = data.getStringExtra("description");
        if (description == null) description = "no description";

        double amount = Double.parseDouble(data.getStringExtra("amount"));

        h.setDescription(description);
        h.setAmount(amount);
        //h.setTimestamp(System.currentTimeMillis());

        //this is where I am updating my arraylist....

        historyItems.add(position,h);
        adapter.notifyDataSetChanged();


        user.makeEdit(h);

    }
}

这是在我的自定义适配器中。

public class HistoryCustomAdapter extends BaseAdapter {

Context context;
ArrayList<HistoryItem> historyItems;
HashMap<String,String> iconMapper;

private static LayoutInflater inflater=null;

public HistoryCustomAdapter(Context context, ArrayList<HistoryItem> historyItems, HashMap<String, String> iconMapper) {
    this.context=context;
    this.historyItems=historyItems;
    this.iconMapper=iconMapper;
    inflater = ( LayoutInflater )context.
            getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getCount() {
    return historyItems != null ? historyItems.size() : 0;
}

@Override
public Object getItem(int position) {
    return historyItems.get(position);
}

@Override
public long getItemId(int position) {
    return 0;
}

@Override
@Override
public View getView(int position, View convertView, ViewGroup parent) {

    Holder holder;
    if (convertView == null) {
        holder = new Holder();
        LayoutInflater vi = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = vi.inflate(R.layout.history_item, parent, false);

        holder.tvCat = (TextView)convertView.findViewById(R.id.tv_category);
        holder.tvAmt = (TextView)convertView.findViewById(R.id.tv_amount);
        holder.tvDate = (TextView)convertView.findViewById(R.id.tv_date);
        holder.img = (ImageView)convertView.findViewById(R.id.iv);
        convertView.setTag(holder);

    }

    holder=(Holder)convertView.getTag();
    HistoryItem historyItem;
    historyItem = historyItems.get(position);

    holder.tvCat.setText(historyItem.getCategory());
    holder.tvAmt.setText(historyItem.getAmount()+"");

    DateFormat df = new SimpleDateFormat("yyyy/MM/dd kk:mm:ss");
    Calendar c    = Calendar.getInstance();
    c.setTimeInMillis(historyItem.getTimestamp());
    Date day      = c.getTime();

    holder.tvDate.setText(df.format(day));

    Resources res = context.getResources();
    String mDrawableName = iconMapper.get(historyItem.getCategory());
    int resID = res.getIdentifier(mDrawableName , "drawable", context.getPackageName());
    holder.img.setImageResource(resID);

    return convertView;
}

public void refresh(ArrayList<HistoryItem> historyItems)
{
    this.historyItems.clear();
    this.historyItems.addAll(historyItems);
    //notifyDataSetChanged();
}

public class Holder
{
    TextView tvCat,tvAmt,tvDate;
    ImageView img;
}

}

我不知道为什么我的列表视图没有立即更新...我应该切换到 ArrayAdapters 吗？

Answer 1

尝试清除您的this.historyItems，然后清除this.historyItems.addAll(historyItems)。希望它有效！

无论如何，如果你尝试 ViewHolder Pattern，你应该重用它：

if (rowView == null) {
   // init view, holder
   rowView.setTag(holder)
} else {
   holder = (Holder) rowView.getTag();
}

// fill data

这可能是您的列表视图没有立即反映的原因。

Answer 2

当您将新的 ArrayList 分配给 this.historyItems 时，将无法再通知数据，因为您丢失了对您最初指定的 Arraylist 的引用。

如果您希望该方法起作用，您需要覆盖getCount 和getItem。

但你也需要

this.historyItems.clear();
this.historyItems.addAll(historyItems);

或者，如果使用 ArrayAdapter，则不需要将列表作为成员变量

clear();
addAll(historyItems);

那么，notifyDatasetChanged 应该可以工作了

Answer 3

在拨打adapter.notifyDataSetChanged();之前尝试.setAdapter(adapter)

Answer 4

请检查此方法

public void refresh(ArrayList<HistoryItem> historyitems)
{
    this.historyItems=historyitems;
    notifyDataSetChanged();
}

这样做。它会工作