使用RxJava3在房间数据库的片段中填充微调器的问题

概述 我正在尽力遵循MVVM模式。在我的数据模型中，我有一个实体“languages”及其通过存储库访问的对应DAO。这个存储库反过来为我的viewmodel提供信息，并通过片段中的工厂进行实例化。或者，从另一个角度看，我的片段->视图模型工厂->视图模型->存储库->DAO->实体

对于阵列适配器“适合”MVVM模式的位置，我有点困惑。该特定片段设计用于显示一组字段（名称、语言等），作为应用程序中的“配置文件”创建页面

问题： 我试图用语言列表填充微调器，这样当选择微调器中的语言时，软件中实际会使用相应的值（想想：文本-值对）。我真的不知道我在做什么，但我正在尽可能快地失败。目前，我在fragment onViewCreated方法中遇到以下错误：

Android Studio错误：“无法解析“Observable”中的方法“observe”

代码

语言实体

@Entity
public class languages {
    @PrimaryKey(autoGenerate = true)
    @NonNull
    public Long langNo;
    public String langDesc;
    @ColumnInfo(defaultValue = "CURRENT_TIMESTAMP")
    public Long langUpdatedDate;
    @ColumnInfo(defaultValue = "CURRENT_TIMESTAMP")
    public Long langCreatedDate;
}

public class newProfileRepository {
    private final syllableDB m_db;
    private static newProfileRepository s_Instance;
    private usersDAO u_dao;
    private languagesDAO l_dao;
    private usersXlanguagesDAO uxl_dao;
    

    public newProfileRepository(final syllableDB db){
        m_db  = db;
        u_dao = m_db.usersDao();
        l_dao = m_db.languagesDAO();
        uxl_dao = m_db.usersXlanguagesDAO();
    }

    public static newProfileRepository getInstance(final syllableDB db) {
        if (s_Instance == null) {
            synchronized (newProfileRepository.class) {
                if (s_Instance == null) {
                    s_Instance = new newProfileRepository(db);
                }
            }
        }
        return s_Instance;
    }

    public Single<List<languages>> getLanguages(){
        return l_dao.getLanguages();
    }
    //...
}

DAO

@Dao
public interface languagesDAO {
    @Update
    Completable update(languages language);

    @Insert
    Completable insert(languages language);

    @Delete
    Completable delete(languages language);

    //for array deletion
    @Delete
    Completable delete(languages... language);

    //Queries
    @Query("SELECT * FROM languages;")
    Single<List<languages>> getLanguages();
}

我尝试过的

我真的尝试过使用这里介绍的文本-值对功能： （这让我摸不着头脑，为什么“观察”会引起问题）

使用此处显示的可观察机械：

…还有这里的ID内容（我已经对下面两个链接中的许多代码进行了注释，因为我还没走那么远）： 和

经常困扰我的问题是，我无法遍历带有for-each循环的单个对象，因为当我将“语言”对象列表转换为“语言”对象列表时，“foreach未为RxJava定义…Single”（或类似的内容）

我以为我可以将语言对象作为单个对象检索，然后在.map或.flatMap函数中将它们添加到我的列表中，但这就是我的目的

问题

对于MVVM模式，访问存储库和处理微调器初始化的位置的选择是否合理？我想确保我在使用这个框架，而不是反对它，但我不知道我在做什么，而使用RxJava，我感到非常困惑。我在想，如果我对如何更好地组织我的代码有了一些指导，那么也许它会阻止我尝试做一些愚蠢的事情

我甚至应该尝试让“中间”语言.java类工作，还是完全放弃它？换句话说，我是否应该不担心将RxJava转换为LiveData会有什么好处（或者我认为我理解的是什么好处）？似乎我误解了什么，它混淆了我的代码，使我的生活比需要的困难得多

我应该怎么做

我应该在subscribeToModel中做什么？我已经读到，业务逻辑应该为服务保留。因此，到目前为止，在我看来，应该是存储库负责将内容传递给计算，但我对如何对“填充”逻辑进行分类有点模糊，因此对于在片段级别上进行任何形式的操作都很犹豫。然而，这让我想“好吧，那么应该去那里做什么呢？”

提前非常感谢您为我们提供的任何信息

public class SpinLangAdapter extends ArrayAdapter<language> {

    private Context context;
    private ArrayList<language> tvPairs = new ArrayList<>();
    private List<languages> langs;
    private newProfileRepository newP_repo;
    private syllableDB db;

    public SpinLangAdapter(Context context, int textViewResourceId,List<language> list){
        super(context,textViewResourceId);
        this.context = context;
        this.tvPairs = new ArrayList<language>(list);
    }


    //This isn't used as I'm not even getting this far...
    public void setLangs(List<languages> newLangs){
        langs = newLangs;
        notifyDataSetChanged();
    }

   /* @Override
    public int getCount(){
        return tvPairs.size();
    }

    @Override
    public language getItem(int position){
        return tvPairs.get(position);
    }*/

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

    //SO Link: https://stackoverflow.com/questions/1625249/android-how-to-bind-spinner-to-custom-object-list   
    //again, not used (yet)
    /*@Override
    public View getView(int position, View convertView, ViewGroup parent) {        
        TextView label = (TextView) super.getView(position, convertView, parent);
        label.setTextColor(Color.BLACK);        
        label.setText(tvPairs.get(position).getLangDesc());
        return label;
    }*/
}

public class createNewProfileViewModel extends AndroidViewModel {
    private static final String QUERY_KEY = "QUERY";

    private final newProfileRepository m_Repository;
    private Single<List<languages>> m_Langs;   

    public createNewProfileViewModel(Application application,  newProfileRepository newProfileRepo) {
        super(application);
        m_Repository = newProfileRepo;
        m_Langs = m_Repository.getLanguages();
       
    }
   
    public Observable<List<languages>> getLangListObservable(){
        Single<List<languages>> items = m_Repository.getLanguages();
        items.flattenAsObservable(new Function<List<languages>, Iterable<?>>() {
            @Override
            public Iterable<?> apply(List<languages> languages) throws Throwable {
                return languages;
            }
        })
        .toList();
        return null;
    }
}

public class createNewProfileFragment extends Fragment implements View.OnTouchListener,View.OnClickListener {
    private static final String LOG_TAG = com.electricbamboo.syllable.ui.createNewProfileFragment.class.getSimpleName();
    private CreateNewProfileBinding mBinding;
    private Context m_Context;

    private profileService PCS;

    private SpinLangAdapter nativeSLAdapter;
    private SpinLangAdapter targetSLAdapter;
    private List<language> spinnerListLangs;

    private Float tmpFZero=null;
    private Long tmpNativeLangNo = 0L;
    private ArrayList<Long> tmpTargetLangNos = new ArrayList<>();

    public createNewProfileFragment(){}

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        m_Context = context;
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                                @Nullable Bundle savedInstanceState) {
        Log.d(LOG_TAG, "Starting New Profile Creation");

        mBinding = DataBindingUtil.inflate(getLayoutInflater(), R.layout.create_new_profile, container, false);

        return mBinding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState){
        newProfileViewModelFactory factory = new newProfileViewModelFactory(requireActivity().getApplication());

        final createNewProfileViewModel model = new ViewModelProvider(this,factory).get(createNewProfileViewModel.class);
        mBinding.setLifecycleOwner(getViewLifecycleOwner());

        nativeSLAdapter = new SpinLangAdapter(m_Context, android.R.layout.simple_spinner_dropdown_item,spinnerListLangs);
        mBinding.spCreateNativeLang.setAdapter(nativeSLAdapter);

        targetSLAdapter = new SpinLangAdapter(m_Context, android.R.layout.simple_spinner_dropdown_item,spinnerListLangs);
        mBinding.spCreateTargetLang.setAdapter(targetSLAdapter);

        // Doesn't compile, error thrown here ("Cannot resolve method 'observe' in 'Observable'")
        model.getLangListObservable().observe(this, new Observer<List<languages>>(){
            @Override
            public void onChanged(@Nullable final List<languages> langs){
                for(languages l : langs){
                    language tmpLang = null;
                    tmpLang.setLangNo(l.langNo);
                    tmpLang.setLangDesc(l.langDesc);
                    spinnerListLangs.add(tmpLang);
                }
                targetSLAdapter.notifyDataSetChanged();
                nativeSLAdapter.notifyDataSetChanged();
            }
        });

        mBinding.spCreateNativeLang.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {
                language language = nativeSLAdapter.getItem(position);
                tmpNativeLangNo = language.getLangNo();
            }

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

        mBinding.spCreateTargetLang.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {
                language language = targetSLAdapter.getItem(position);
                tmpTargetLangNos.add(language.getLangNo());
            }

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

        subscribeToModel(model);
    }

    private void subscribeToModel(final createNewProfileViewModel model){
          //Fairly certain SOMETHING is supposed to go here, just unsure as to what
    }

  //...omitting onClick, onTouch, onStart, onPause, onResume, etc.

public class language extends LiveData {
    private Long langNo;
    private String langDesc;

    //Getters
    public Long getLangNo(){
        return langNo;
    }

    public String getLangDesc(){
        return langDesc;
    }

    //Setters
    public void setLangNo(Long langNo){
        this.langNo = langNo;
    }

    public void setLangDesc(String langDesc){
        this.langDesc = langDesc;
    }

}