自定义ListView适配器引发UnsupportedOperationException

Question

这是我遵循的使用自定义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

环顾四周，似乎是使用数组初始化适配器。请参阅带有ArrayAdapter.remove的UnsupportedOperationException和无法在ListView中修改ArrayAdapter：UnsupportedOperationException

尝试使用ArrayList而不是array赞这样

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类中完成到的转换，您将需要删除Weather data[] = null;和的所有引用（例如，在构造函数内部），因为ArrayAdapter它为您保留了数据，您可以使用getItem进行访问

因此，在您的getView函数内部，您将更Weather weather = data[position];改为Weather weather = getItem(position);

更新 修改您的代码

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);
}