Android MVVM设计模式在logcat中不显示空值,但在调用api设置数据时,它显示了repository类中arraylist的大小

public class ImagesRepositoy {
private static ImagesRepositoy instance;
private ArrayList<Images> dataset = new ArrayList<>();
private RequestQueue queue;
private static Context mCtx;
private StringRequest request;

public ImagesRepositoy() {
}

public ImagesRepositoy(Context context) {
    mCtx = context;
}

public static ImagesRepositoy getInstance() {
    if (instance == null) {
        instance = new ImagesRepositoy();
    }
    return instance;
}

public MutableLiveData<List<Images>> getIMAGES() {
    getFromApi();
    MutableLiveData<List<Images>> data = new MutableLiveData<>();
    data.setValue(dataset);// here I am getting empty array size
    Log.e("DATA",data.getValue().toString());
    return data;
}

private void getFromApi() {
    Log.e("YUPP", "HANN");
    request = new StringRequest(Request.Method.GET, ImageApi + "APIKEY&limit=25", new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            Log.d("responsefromserv", response + "null");
            try {


                JSONObject jsonObject = new JSONObject(response);
                JSONObject images, original, jsonObject3;
                JSONArray jsonArray = jsonObject.getJSONArray("data");
                Log.d("DATAATA", jsonObject.getJSONArray("data") + ".");


                for (int i = 0; i < jsonArray.length(); i++) {
                    Images Imgs = new Images();
                    images = jsonArray.getJSONObject(i);
                    original = images.getJSONObject("images");
                    jsonObject3 = original.getJSONObject("original");
                    Imgs.setUrl(jsonObject3.getString("url"));
                    Log.e("JSONE3", Imgs.getUrl() + "");
                    dataset.add(Imgs);   // HERE I AM GETTING 25 size

                }


            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("error", error.toString());
        }
    });
    queue = Volley.newRequestQueue(mCtx);

    queue.add(request);

}}

查看模型,从中获取逻辑实例

  public class HomeViewModel extends ViewModel {
private ImagesRepositoy repositoy;
private MutableLiveData<List<Images>> url;


public void init() {
    if (url != null) {
        return;
    }
    Log.e("INIT","OK");
    repositoy = ImagesRepositoy.getInstance();
    url = repositoy.getIMAGES();
}

public LiveData<List<Images>> getIMAGES() {
    Log.e("UUUU",url.getValue().toString());
    return url;
}}




        
  **THIS IS CALLED WHEN I CHANGE SCREEN ROTATION

homeViewModel.getCallApi();此API从服务器获取GIF图像,但我不知道为什么在我的设备旋转时调用此API。如有任何建议,将不胜感激**

  public class HomeFragment extends Fragment {

private List<Images> imagesList = new ArrayList<>();
private RecyclerView recyclerView;
private RequestQueue queue;
private MyGifAdapter myGifAdapter;
private HomeViewModel homeViewModel;

public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {

    View root = inflater.inflate(R.layout.fragment_home, container, false);
    recyclerView = root.findViewById(R.id.my_recycler_view);
    homeViewModel =
            new ViewModelProvider(this).get(HomeViewModel.class);
    new HomeViewModel(getActivity());
    homeViewModel.getCallApi();
    homeViewModel.getIMAGES().observe(getActivity(), new Observer<ArrayList<Images>>() {
        @Override
        public void onChanged(ArrayList<Images> s) {

            if(s!=null)
            {
                imagesList=s;
                myGifAdapter.setImages(s);


            }

            myGifAdapter.notifyDataSetChanged();
        }
    });
    GridLayoutManager gridLayoutManager = new GridLayoutManager(getActivity(), 3);
    recyclerView.setLayoutManager(gridLayoutManager); // set LayoutManager to RecyclerView
    Log.e("VMMM", homeViewModel.getIMAGES().getValue() + ".");
    myGifAdapter = new MyGifAdapter(getContext(), homeViewModel.getIMAGES().getValue());
    recyclerView.setAdapter(myGifAdapter); // set the Adapter to RecyclerView

    return root;
}