自定义 ListView 适配器抛出 UnsupportedOperationException

Question

This is the tutorial that I followed 使用自定义 Listview 适配器。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

环顾四周，似乎用数组初始化适配器是个问题。见UnsupportedOperationException with ArrayAdapter.remove和Unable to modify ArrayAdapter in ListView: UnsupportedOperationException

尝试使用ArrayList，而不是像这样的array

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.

如果您觉得懒惰，可以通过这种方式将您的 array 转换为 ArrayList

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

要在WeatherAdapter 类中完成到ArrayList 的转换，您需要删除Weather data[] = null; 及其所有引用（例如在构造函数中），因为ArrayAdapter 为您保存数据，您可以使用getItem访问它

因此，在您的 getView 函数中，您可以将 Weather weather = data[position]; 更改为 Weather weather = getItem(position);

更新 修改你的更新代码

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);
}