RecyclerView.onBindViewHolder只调用一次

Question

经过几个小时的研究,我终于咨询了官方的帮助.

我有一个完美的RecyclerView.Adapter和RecyclerView.ViewHolders.但由于某些原因我不明白,RecyclerView.Adapter.onBindViewHolder未正确调用.

    private class AttendeeAdapter extends RecyclerView.Adapter<AttendeeHolder> {
    /*FIELDS*/
    private List<Attendee> mAttendeeList;

    /*CONSTRUCTORS*/
    public AttendeeAdapter(List<Attendee> attendees) {
        mAttendeeList = attendees;
        //Log.i(TAG, "AttendeeAdapter size: " + getItemCount());
    }

根据Log消息(项目计数作为预期列表的大小),我假设AttendeeAdapter已正确实例化.

所以我希望onBindViewHolder(VH,int)方法的调用次数与List的大小相同,但事实并非如此.该方法仅被称为ONCE!

    /*METHODS*/
    @Override
    public AttendeeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
        View itemView = layoutInflater.inflate(R.layout.list_attendee, parent, false);
        return new AttendeeHolder(itemView);
    }

    @Override
    public void onBindViewHolder(AttendeeHolder holder, int position) {
        Attendee attendee = mAttendeeList.get(position);
        holder.bindAttendee(attendee, position);

        Log.i(TAG, "Binding ViewHolder #" + position);
        /* Binding ViewHolder #0 and that's it */
    }

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

我的AttendeeHolder(扩展RecyclerView.ViewHolder)如下:

    private class AttendeeHolder extends RecyclerView.ViewHolder {
    /*FIELDS*/
    private EditText mAttendeeNameEditText;
    private Attendee mAttendee;

    /*CONSTRUCTOR*/
    public AttendeeHolder(View itemView) {
        super(itemView);
        mAttendeeNameEditText = (EditText) itemView.findViewById(R.id.edit_text_list_item);
        mAmountEditTextList = new ArrayList<>(eventMaxCount);
      }

    /*METHODS*/
    public void bindAttendee(Attendee attendee, final int position) {
        mAttendee = attendee;
        String attendeeName = mAttendee.getName();

        // Set the name to the EditText if a name has already been set
        if (attendeeName != null) {
            mAttendeeNameEditText.setText(attendeeName);
        }
    }
}

并在主代码中实现为

List<Attendee> attendees = AttendeeLab.get().getAttendeeList();
     mAttendeeAdapter = new AttendeeAdapter(attendees);
     mAmountRecyclerView.setAdapter(mAttendeeAdapter);

我想代码可以工作(我想我没有做任何改动)但是gradle依赖关系可能没有正确设置.那是我尝试将recyclerview-v7:23.3.0修改为recyclerview-v7:23.1.0或其他任何东西(它们都没有工作).

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.3.0'
compile 'com.android.support:design:23.3.0'
compile 'com.android.support:support-v4:23.3.0'
compile 'com.android.support:recyclerview-v7:23.1.2'
}

任何帮助或评论将不胜感激.我希望从现在开始几个小时之后,我会告诉你头痛的事.

Answer 1

问题不在您的代码中.确保设置layout_height为wrap_contentRecyclerView子项.

Answer 2

处理RecyclerView周期中的onBindViewHolder行为.RecyclerView.ViewHolder位置0 itemView

android:layout_height="match_parent"

占用当前显示的屏幕.应该触发Scroll和onBindViewHolder,但要确保正确设置了getItemCount.

解:

android:layout_height="wrap_content"

使用ConstraintLayout作为膨胀itemView的解决方案:

<?xml version="1.0" encoding="utf-8"?>    
<android.support.constraint.ConstraintLayout 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:layout_height="wrap_content"><!-- IMPORTANT -->
    <!-- ... -->
</android.support.constraint.ConstraintLayout>

Answer 3

对所有支持库使用相同的版本：

dependencies {

compile fileTree(dir: 'libs', include: ['*.jar'])

testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.3.0'
compile 'com.android.support:design:23.3.0'
compile 'com.android.support:support-v4:23.3.0'
compile 'com.android.support:recyclerview-v7:23.3.0' //<<< here
}

另外，RecyclerView应该与包一起添加'com.android.support:design:23.3.0'- 覆盖类或Gradle在构建过程中使用此“重复”包所做的任何魔法可能会导致您的问题。