Erro在spinner中使用“setOnItemSelectedListener”时

Question

当我在微调器中使用setOnItemSelectedListener时，会发生错误。 这是我的代码：

public class FragmentAdd extends Fragment {
    private Spinner spinnerProvince;
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        spinnerProvince = (Spinner) getActivity().findViewById(R.id.spinner_province);
        spinnerProvince.setOnItemSelectedListener(new OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {

            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });

        return inflater.inflate(R.layout.fragment_add,container,false);

    }
}

错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setOnItemSelectedListener(android.widget.AdapterView$OnItemSelectedListener)' on a null object reference

我如何解决这个问题。

Answer 1

您应首先对视图进行充气，然后在充气视图上执行id绑定尝试此

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View root = inflater.inflate(R.layout.fragment_add,container,false);
    spinnerProvince = (Spinner) root.findViewById(R.id.spinner_province);
    spinnerProvince.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {

        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });

    return root;

}