自定义ListView适配器抛出UnsupportedOperationException

Question

这是我使用自定义Listview适配器的教程.我遇到的问题是,当我尝试清除适配器时,应用程序崩溃并抛出java.lang.UnsupportedOperationException

if(adapter != null) {
    adapter.clear();
}

更新的代码:

private void setListViewAdapterToDate(int month, int year, int dv)
{
     if(summaryAdapter != null) {
        summaryAdapter.clear();
     }

    setListView(month, year, dv);
    summaryList.addAll(Arrays.asList(summary_data));
    summaryAdapter = new SummaryAdapter(this.getActivity().getApplicationContext(), R.layout.listview_item_row, summaryList);


    summaryAdapter.notifyDataSetChanged();
    calendarSummary.setAdapter(summaryAdapter);
}

Answer 1

看一下,似乎用数组初始化适配器是个问题.请参阅ArrayAdapter.remove的UnsupportedOperationException,并且无法在ListView中修改ArrayAdapter:UnsupportedOperationException

尝试使用ArrayList而不是array像这样

ArrayList<Weather> weather_data = new ArrayList<Weather>()
weather_data.add( new Weather(R.drawable.weather_cloudy, "Cloudy") );
// continue for the rest of your Weather items.

如果你感到懒惰,您可以转换array成ArrayList这样

ArrayList<Weather> weatherList = new ArrayList<Weather>();
weatherList.addAll(Arrays.asList(weather_data));

要ArrayList在您的WeatherAdapter类中完成转换,您将需要删除它Weather data[] = null;及其所有引用(例如在构造函数内),因为ArrayAdapter为您保存数据,您可以使用getItem访问它

所以,你的内部getView功能,你会改变Weather weather = data[position];对Weather weather = getItem(position);

更新 修改您的udated代码

private void setListViewAdapterToDate(int month, int year, int dv)
{
    setListView(month, year, dv); 
     if(summaryAdapter != null) {
        summaryAdapter.clear();
        summaryAdapter.addAll( summaryList );
        summaryAdapter.notifyDataSetChanged();
     } else {
         summaryList.addAll(Arrays.asList(summary_data));
         summaryAdapter = new SummaryAdapter(this.getActivity().getApplicationContext(), R.layout.listview_item_row, summaryList);
     }
    calendarSummary.setAdapter(summaryAdapter);
}