Question

任何人都可以帮忙解决这个问题，我试图在一个片段中添加一个微调器，使用自定义适配器，因为我的微调器将有动态字符串，困惑如何将微调器添加到片段，我尝试了下面的代码，并得到了ClassCastException：android.app.Application无法强制转换为android .widget.AdapterView $ OnItemSelectedListener Exception。

public class Questions_Fragment extends Fragment implements OnItemSelectedListener {

List<String> list_products = new ArrayList<String>();

 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
 {
         View rootView = inflater .inflate(R.layout.activity_questions, container, false);

         return rootView;
 }

 @Override 
    public void onActivityCreated(Bundle savedInstanceState) {  
        super.onActivityCreated(savedInstanceState);  

        //add data to List
        list_products.add("0");
        list_products.add("1");
        list_products.add("2");

        Spinner spinner = (Spinner)getActivity().findViewById(R.id.products_spinner);
        int hidingItemIndex = 0;
        CustomAdapter dataAdapter = new CustomAdapter(getActivity().getApplicationContext(),
                android.R.layout.simple_spinner_item, list_products,
                hidingItemIndex);
        dataAdapter
                .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(dataAdapter);
        spinner.setOnItemSelectedListener((OnItemSelectedListener) getActivity().getApplicationContext());
        } 
 public void onItemSelected(AdapterView<?> parent, View view, int position,
            long id) {
        // TODO Auto-generated method stub      
        if (position == 1) {
            Log.d("Succes","Item Selected is 1");
        }
        }

    class CustomAdapter extends ArrayAdapter<String> {

        private int hidingItemIndex;

        public CustomAdapter(Context questions_Fragment, int textViewResourceId,
                List<String> list, int hidingItemIndex) {
            super(questions_Fragment, textViewResourceId, list);
            this.hidingItemIndex = hidingItemIndex;
        }

        @Override
        public View getDropDownView(int position, View convertView,
                ViewGroup parent) {
            View v = null;
            if (position == hidingItemIndex) {
                TextView tv = new TextView(getContext());
                tv.setVisibility(View.GONE);
                v = tv;
            } else {
                v = super.getDropDownView(position, null, parent);
            }
            return v;
        }
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        // TODO Auto-generated method stub

    }

}

Answer 1

由于你的Questions_Fragment实现了监听器所以它应该是

spinner.setOnItemSelectedListener(this);

ClassCastException：android.app.Application无法强制转换为android.widget.AdapterView $ OnItemSelectedListener

1 个答案: