使用了Banner2：https://github.com/youth5201314/banner

在Fragment中使用Banner2，报错：RecyclerView: No adapter attached; skipping layout。

请求数据部分

显示部分

结果与日志

奇怪的是在activity里也使用了类似的代码，却可以显示

============补充============

代码结构是学习领券联盟的

HomePresenterImpl:

package com.example.smart_1.presenter.impl;

import com.example.smart_1.model.Api;
import com.example.smart_1.model.domain.LooperBean;
import com.example.smart_1.presenter.IHomePresenter;
import com.example.smart_1.ui.IHomeCallback;
import com.example.smart_1.utils.LogUtil;
import com.example.smart_1.utils.RetrofitManager;

import java.net.HttpURLConnection;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

public class HomePresenterImpl implements IHomePresenter {
    @Override
    public void getLooperContent() {
        if (mCallback == null) {
            return;
        }
        mCallback.onLoading();

        Api api = RetrofitManager.getRetrofit().create(Api.class);
        api.getLooperBean().enqueue(new Callback<LooperBean>() {
            @Override
            public void onResponse(Call<LooperBean> call, Response<LooperBean> response) {
                LooperBean body = response.body();
                int code = body.getCode();
                LogUtil.d(HomePresenterImpl.this, "code is ==> " + code);
                if (code == HttpURLConnection.HTTP_OK) {
                    mCallback.onLooperContentLoaded(body);
                } else {
                    LogUtil.d(HomePresenterImpl.this, "请求失败，" + body.getMsg());
                    mCallback.onError();
                }
            }

            @Override
            public void onFailure(Call<LooperBean> call, Throwable throwable) {
                LogUtil.e(HomePresenterImpl.this, "网络错误。。");
                mCallback.onError();
            }
        });
    }


    IHomeCallback mCallback = null;

    @Override
    public void registerViewCallback(IHomeCallback callback) {
        mCallback = callback;
    }

    @Override
    public void unregisterViewCallback(IHomeCallback callback) {
        mCallback = null;
    }
}

HomeFragment:

package com.example.smart_1.ui.fragment;

import android.content.Context;
import android.view.View;

import com.bumptech.glide.Glide;
import com.example.smart_1.R;
import com.example.smart_1.base.BaseFragment;
import com.example.smart_1.model.domain.LooperBean;
import com.example.smart_1.presenter.impl.HomePresenterImpl;
import com.example.smart_1.ui.IHomeCallback;
import com.example.smart_1.utils.Constants;
import com.example.smart_1.utils.LogUtil;
import com.youth.banner.Banner;
import com.youth.banner.adapter.BannerImageAdapter;
import com.youth.banner.holder.BannerImageHolder;
import com.youth.banner.indicator.CircleIndicator;

import java.util.ArrayList;
import java.util.List;

public class HomeFragment extends BaseFragment implements IHomeCallback {

    private HomePresenterImpl mHomePresenterImpl;
    private Banner mBanner;
    private Context mContext;

    @Override
    protected void initPresenter() {
        mHomePresenterImpl = new HomePresenterImpl();
        mHomePresenterImpl.registerViewCallback(this);
    }

    @Override
    protected void release() {
        if (mHomePresenterImpl != null) {
            mHomePresenterImpl.unregisterViewCallback(this);
        }
    }

    @Override
    protected void loadData() {
        mHomePresenterImpl.getLooperContent();
    }

    @Override
    protected void initEven() {

    }

    @Override
    protected void initView(View rootView, View currentView) {
        mContext = currentView.getContext();
        mBanner = currentView.findViewById(R.id.home_banner);
    }

    @Override
    protected int getLayoutId() {
        return R.layout.fragment_home;
    }


    private List<LooperBean.RowsBean> mRowsBeans = new ArrayList<>();

    @Override
    public void onLooperContentLoaded(LooperBean body) {
        List<LooperBean.RowsBean> rows = body.getRows();
        mRowsBeans.clear();
        mRowsBeans.addAll(rows);
        LogUtil.d(HomeFragment.this, "rows is ==> " + rows.toString());

        BannerImageAdapter<LooperBean.RowsBean> adapter = new BannerImageAdapter<LooperBean.RowsBean>(mRowsBeans) {
            @Override
            public void onBindView(BannerImageHolder bannerImageHolder, LooperBean.RowsBean rowsBean, int i, int i1) {
                Glide.with(bannerImageHolder.itemView)
                        .load(Constants.BASE_URL + rowsBean.getAdvImg())
                        .into(bannerImageHolder.imageView);
            }
        };

        mBanner.addBannerLifecycleObserver(this)
                .setAdapter(adapter)
                .setIndicator(new CircleIndicator(getActivity()));

        setUpState(State.SUCCESS);
    }

    @Override
    public void onLoading() {
        setUpState(State.LOADING);
    }

    @Override
    public void onError() {
        setUpState(State.ERROR);
    }

    @Override
    public void onEmpty() {
        setUpState(State.EMPTY);
    }
}

BaseFragment:

package com.example.smart_1.base;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import com.example.smart_1.R;

public abstract class BaseFragment extends Fragment {

    private FrameLayout mBaseContainer;
    private View mSuccessView;
    private View mLoadingView;
    private View mErrorView;
    private View mEmptyView;

    public enum State {
        NONE, LOADING, SUCCESS, ERROR, EMPTY
    }

    private State currentState;

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

        View rootView = getRootView(inflater, container);
        mBaseContainer = rootView.findViewById(R.id.base_container);
        loadStatesView(inflater, container);
        View targetView = loadTargetView(inflater, container);
        initPresenter();
        initView(rootView, targetView);
        initEven();
        loadData();

        return rootView;
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        release();
    }

    protected abstract void initPresenter();

    protected abstract void release();

    protected abstract void loadData();

    protected abstract void initEven();

    protected abstract void initView(View rootView, View currentView);

    private void loadStatesView(LayoutInflater inflater, ViewGroup container) {
        mSuccessView = loadTargetView(inflater, container);
        mLoadingView = loadLoadingView(inflater, container);
        mErrorView = loadErrorView(inflater, container);
        mEmptyView = loadEmptyView(inflater, container);

        mBaseContainer.addView(mSuccessView);
        mBaseContainer.addView(mLoadingView);
        mBaseContainer.addView(mErrorView);
        mBaseContainer.addView(mEmptyView);

        setUpState(State.NONE);
    }

    protected void setUpState(State state) {
        this.currentState = state;
        //判断各View的可见性
        mSuccessView.setVisibility(currentState == State.SUCCESS ? View.VISIBLE : View.GONE);
        mLoadingView.setVisibility(currentState == State.LOADING ? View.VISIBLE : View.GONE);
        mErrorView.setVisibility(currentState == State.ERROR ? View.VISIBLE : View.GONE);
        mEmptyView.setVisibility(currentState == State.EMPTY ? View.VISIBLE : View.GONE);
    }

    private View loadEmptyView(LayoutInflater inflater, ViewGroup container) {
        return inflater.inflate(R.layout.fragment_empty, container, false);
    }

    private View loadErrorView(LayoutInflater inflater, ViewGroup container) {
        return inflater.inflate(R.layout.fragment_error, container, false);
    }

    private View loadLoadingView(LayoutInflater inflater, ViewGroup container) {
        return inflater.inflate(R.layout.fragment_loading, container, false);
    }

    private View loadTargetView(LayoutInflater inflater, ViewGroup container) {
        return inflater.inflate(getLayoutId(), container, false);
    }

    protected abstract int getLayoutId();

    private View getRootView(LayoutInflater inflater, ViewGroup container) {
        return inflater.inflate(R.layout.base_fragment_layout, container, false);
    }
}