如何使用JSON数据创建自定义自定义转接器适配器？

Question

当我从列表数据将数据加载到旋转器时，它可以工作。但是，当我为spinner创建适配器时，它不起作用。我的问题是什么？

活动：

final FieldOfficerApiInterface apiService=OperatingApiClient.getClient().create(FieldOfficerApiInterface.class);

        Call<FieldOfficerApiResponse> call = apiService.getAllEOByBranchID(branchid);
        call.enqueue(new Callback<FieldOfficerApiResponse>() {
            @Override
            public void onResponse(Call<FieldOfficerApiResponse> call, Response<FieldOfficerApiResponse> response) {
                List<FieldOfficer> fieldofficerlist=response.body().getFieldofficerlist();
                Log.d(TAG,"Number of Fieldofficerlist received: "+fieldofficerlist.size());

                //*********DROPDOWN******************************************************

                final Spinner spnrFieldOfficer=(Spinner)findViewById(R.id.spinnerFieldOfficer);

                CustomSpinnerAdapter adapter=new CustomSpinnerAdapter(getApplicationContext(),fieldofficerlist);
                spnrFieldOfficer.setAdapter(adapter);

                //*********END DROPDOWN******************************************************
            }

            @Override
            public void onFailure(Call<FieldOfficerApiResponse> call, Throwable t) {
                // Log error here since request failed
                Log.e(TAG,t.toString());

            }
        });

CustomSpinnerAdapter：

public class CustomSpinnerAdapter extends BaseAdapter {

    private List<FieldOfficer> fieldOfficers;
    private Context context;
    LayoutInflater inflter;


    public CustomSpinnerAdapter(Context context, List<FieldOfficer> fieldOfficers) {
        this.context = context;
        this.fieldOfficers = fieldOfficers;
        this.inflter = (LayoutInflater.from(context));
    }

    @Override
    public int getCount() {
        return 0;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        convertView=inflter.inflate(R.layout.custom_spinner_items,null);
        TextView tv=(TextView)convertView.findViewById(R.id.textView2);
        tv.setText(fieldOfficers.get(position).getFoname());
        return convertView;
    }
}

它不需要自定义适配器：

//*********DROPDOWN******************************************************
                ArrayAdapter<FieldOfficer> adapter;
                adapter = new ArrayAdapter<FieldOfficer>(getApplicationContext(), android.R.layout.simple_selectable_list_item,fieldofficerlist); //getApplication()
                //setting adapter to spinner
                spnrFieldOfficer.setAdapter(adapter);
//*********END DROPDOWN******************************************************

Answer 1

旋转器将调用您的getCount()来确定列表中有多少项，在您的实现中，您告诉它列表始终是空的。

将getCount()更改为

@Override
    public int getCount() {
        if (fieldOfficers!= null) {
            return fieldOfficers.size();
        }
        return 0;
    }

Answer 2

像这样更改getCount()

 @Override
    public int getCount() {
        if (fieldOfficers!= null) {
            return fieldOfficers.size();
        }
        return 0;
    }