我的Recyclerview上没有显示任何内容

Question

我无法弄清楚为什么echo $difference->format('%d')中没有显示任何内容。我所做的只是按一个按钮，我想要导航到RecyclerView我将看到我的粉丝列表。以下是我的代码：

XML布局：

follow_list.xml：

Activity

follow_item.xml：

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent" android:id="@+id/follow_list_layout_id"
android:layout_height="match_parent" android:fitsSystemWindows="true">

<android.support.design.widget.AppBarLayout
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:id="@+id/follow_toolbar"
        app:popupTheme="@style/AppTheme.PopupOverlay"
        app:theme="@style/AppTheme.AppBarOverlay"/>

</android.support.design.widget.AppBarLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    <!--<include layout="@layout/include_progress_overlay"/>-->

    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/follow_list"
        />
    </RelativeLayout>

</android.support.design.widget.CoordinatorLayout>

适配器：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:facebook="http://schemas.android.com/apk/res-auto"
    xmlns:fresco="http://schemas.android.com/tools"
    android:layout_height="wrap_content"
    android:layout_width="match_parent">


    <android.support.v7.widget.CardView
        android:layout_height="58dp"
        android:layout_width="match_parent"
        android:id="@+id/follower_card_view">

    <RelativeLayout
        android:background="@drawable/edittext_bg"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:paddingTop="8dp"
        android:layout_height="match_parent"
        android:paddingBottom="8dp">

    <com.facebook.drawee.view.SimpleDraweeView
        android:id="@+id/follower_profile_picture"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        fresco:placeholderImageScaleType="centerCrop"
        fresco:placeholderImage="@mipmap/blank_prof_pic"
        fresco:roundedCornerRadius="5dp"
        fresco:roundAsCircle="true"
        />

        <TextView
            android:layout_marginLeft="72dp"
            android:id="@+id/follower_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="16sp"
            android:fontFamily="sans-serif-medium"
            android:layout_centerVertical="true" />

        <CheckBox
            android:id="@+id/follower_checkbox"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:focusable="false"
            android:paddingRight="16dp"
            android:focusableInTouchMode="false"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:layout_alignParentEnd="true" />

    </RelativeLayout>

</android.support.v7.widget.CardView>

</LinearLayout>

显示关注者的类：

public class FollowerRecyclerViewAdapter extends RecyclerView.Adapter<FollowerRecyclerViewAdapter.FollowerViewHolder>{

    private List<User> followers;

    public void setFollowers(List<User> followers) {
        this.followers = followers;
    }

    public static User containsId(List<User> list, String id) {
        for (User object : list) {
            if (object.getUserId().equals(id)) {
                return object;
            }
        }
        return null;
    }

    public FollowerRecyclerViewAdapter(List<User> followers) {
        this.followers = followers;
    }

    public List<User> getFollowers(){
        return this.followers;
    }

    @Override
    public int getItemCount() {
        return followers.size();
    }

    public static class FollowerViewHolder extends RecyclerView.ViewHolder {
        CardView cardViewfollower;
        TextView name;
        CheckBox isFollowingCheckBox;
        SimpleDraweeView followerProfilePhoto;

        FollowerViewHolder(View itemView) {
            super(itemView);
            cardViewfollower = (CardView) itemView.findViewById(R.id.follower_card_view);
            name = (TextView) itemView.findViewById(R.id.follower_name);
            followerProfilePhoto = (SimpleDraweeView) itemView.findViewById(R.id.follower_profile_picture);
            isFollowingCheckBox = (CheckBox) itemView.findViewById(R.id.follower_checkbox);
        }
    }

    @Override
    public void onBindViewHolder(FollowerViewHolder followerViewHolder, int i) {
        final User currentItem = getItem(i);
        followerViewHolder.name.setText(currentItem.getName());
        DraweeController controller = TabsUtil.getImage(currentItem.getUserId());
        RoundingParams roundingParams = RoundingParams.fromCornersRadius(5f);
        roundingParams.setRoundAsCircle(true);
        followerViewHolder.followerProfilePhoto.getHierarchy().setRoundingParams(roundingParams);
        followerViewHolder.followerProfilePhoto.setController(controller);
    }

    @Override
    public FollowerViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.follower_item, viewGroup, false);
        FollowerViewHolder pvh = new FollowerViewHolder(v);
        return pvh;
    }

    private User getItem(int position)
    {
        return followers.get(position);
    }

    public void add(User follower){
        for(int i = 0; i < followers.size(); i++) {
            if(follower.getId().equals(followers.get(i).getId())) {
                return;
            }
        }
        followers.add(follower);
        notifyItemInserted(followers.size() + 1);
        notifyItemRangeChanged(followers.size() + 1, followers.size());
    }

    public void remove(Follower item) {
        int position = followers.indexOf(item);
        followers.remove(position);
        notifyItemRemoved(position);
    }

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
    }

我不确定为什么public class FollowingList extends AppCompatActivity { FireBaseApplication application; DatabaseQuery databaseQuery; View progressOverlay; String posterUserId; String posterName; String postStatus; String postTimeStamp; String postTitle; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.follow_list); application = ((FireBaseApplication) getApplication()); databaseQuery = new DatabaseQuery(this); //Set up action bar setupActionBar(); progressOverlay = findViewById(R.id.progress_overlay); //AndroidUtils.animateView(progressOverlay, View.VISIBLE, 0.9f, 200); setupActivity(savedInstanceState); //All we need to do is render the page now RecyclerView recyclerView = (RecyclerView) findViewById(R.id.follow_list); RecyclerView.ItemAnimator animator = recyclerView.getItemAnimator(); if (animator instanceof SimpleItemAnimator) { ((SimpleItemAnimator) animator).setSupportsChangeAnimations(false); } //Assuming we refresh the followers list, we have to make sure that new followers are loaded application.getFollowingRecyclerViewAdapter().notifyDataSetChanged(); LinearLayoutManager llm = new LinearLayoutManager(this); recyclerView.setLayoutManager(llm); recyclerView.setAdapter(application.getFollowingRecyclerViewAdapter()); } private void setupActionBar(){ Toolbar toolbar = (Toolbar) findViewById(R.id.follow_toolbar); setSupportActionBar(toolbar); //Back bar enabled getSupportActionBar().setDisplayHomeAsUpEnabled(true); getSupportActionBar().setDisplayShowHomeEnabled(true); getSupportActionBar().setDisplayShowCustomEnabled(true); //Toggle bar enabled } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: onBackPressed(); return true; default: return super.onOptionsItemSelected(item); } } } 没有显示我RecyclerView的任何内容，但我们将不胜感激。谢谢！