Question

我正在尝试填充微调器，但是由于某些原因，在尝试通过对象列表时出现错误。请看一下吧：

代码：

public class AddFacultyFragment extends Fragment {

@BindView(R.id.spinner_search_UniFac)
Spinner spinner_search_UniFac;
ArrayList<University> list = new ArrayList<>();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_add_faculty,
            container,
            false);
    ButterKnife.bind(this, view);
    FirebaseFirestore db = FirebaseFirestore.getInstance();
    CollectionReference docRef = db.collection("university");
    docRef.get().addOnCompleteListener((OnCompleteListener<QuerySnapshot>) task -> {
        if (task.isSuccessful()) {
            for(DocumentSnapshot a : task.getResult()){
                University u = new University();
                u.setID(a.getId());
                u.setDesc(a.get("Desc").toString());
                list.add(u);
            }
        }
    });
    ArrayAdapter<University> spinnerArrayAdapter = new ArrayAdapter<University>
            (this, android.R.layout.simple_spinner_item,
                    list);
    spinnerArrayAdapter.setDropDownViewResource(android.R.layout
            .simple_spinner_dropdown_item);
    spinner_search_UniFac.setAdapter(spinnerArrayAdapter);
    return view;
}

public AddFacultyFragment() {
    // Required empty public constructor
}

}

先谢谢您。这是错误

错误：找不到适用于ArrayAdapter（AddFacultyFragment，int，List）的合适的构造函数构造函数ArrayAdapter.ArrayAdapter（Context，int，int）不适用（参数不匹配； AddFacultyFragment无法转换为Context）构造函数ArrayAdapter.ArrayAdapter（Context，int，String []）不适用（参数不匹配； AddFacultyFragment无法转换为Context）构造函数ArrayAdapter.ArrayAdapter（Context，int，List）不适用（参数不匹配； AddFacultyFragment无法转换为上下文）

Answer 1

我认为您所缺少的只是正确的上下文。您不能在片段上使用this，而必须使用getContext()，它应该可以工作。像这样：

公共类AddFacultyFragment扩展Fragment {

@BindView(R.id.spinner_search_UniFac)
Spinner spinner_search_UniFac;
ArrayList<University> list = new ArrayList<>();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_add_faculty,
            container,
            false);
    ButterKnife.bind(this, view);
    FirebaseFirestore db = FirebaseFirestore.getInstance();
    CollectionReference docRef = db.collection("university");
    docRef.get().addOnCompleteListener((OnCompleteListener<QuerySnapshot>) task -> {
        if (task.isSuccessful()) {
            for(DocumentSnapshot a : task.getResult()){
                University u = new University();
                u.setID(a.getId());
                u.setDesc(a.get("Desc").toString());
                list.add(u);
            }
        }
    });
    ArrayAdapter<University> spinnerArrayAdapter = new ArrayAdapter<University>
            (getContext(), android.R.layout.simple_spinner_item,
                    list);
    spinnerArrayAdapter.setDropDownViewResource(android.R.layout
            .simple_spinner_dropdown_item);
    spinner_search_UniFac.setAdapter(spinnerArrayAdapter);
    return view;
}

public AddFacultyFragment() {
    // Required empty public constructor
}

}

检索数据后，Firestore Spinner错误传递列表

1 个答案: