Question

我正在开发一个Android应用程序，我使用RecyclerView来显示项目列表。我从服务器获取列表为json.So我的问题是在这个列表中我得到另一个列表作为item.That是如果我的主要arraylist包含标题和材料，材料是另一个arraylist。所以你能建议一个解决方案，在recyclerview中显示一个列表。

以下代码是我的适配器

public class CurriculumAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private Context mContext;
    private ArrayList<Curriculum> mArrayListCurriculum;

    public CurriculumAdapter(Context mContext, ArrayList<Curriculum> mArrayListCurriculum) {
        this.mContext = mContext;
        this.mArrayListCurriculum = mArrayListCurriculum;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.adapter_key_features, parent,false);
        return new KeyFeatureViewHolder(v);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

        if (holder instanceof KeyFeatureViewHolder) {
            ((KeyFeatureViewHolder) holder).mTextViewFeatureTitle.setText(mArrayListCurriculum.get(position).getTitle());
        }
    }

    @Override
    public int getItemCount() {
        return mArrayListCurriculum == null ? 0 : mArrayListCurriculum.size();
    }

    public static class KeyFeatureViewHolder extends RecyclerView.ViewHolder {

        public TextView mTextViewFeatureTitle;

        public KeyFeatureViewHolder(View itemView) {
            super(itemView);
            mTextViewFeatureTitle = (TextView) itemView.findViewById(R.id.txtFeature);
        }
    }
}

下面的代码是带有虚拟arraylist数据的片段

public class CourseCurriculumFragment extends Fragment {

    private FragmentInterface mFragmentInterface;
    private ArrayList<Curriculum> mArrayListCurriculum;
    private ArrayList<Material> mArrayListMaterial;
    private RecyclerView mRecyclerViewCurriculum;
    private LinearLayoutManager mLinearLayoutManager;
    private CurriculumAdapter mCurriculumAdapter;

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_course_curriculum, container, false);
        return view;
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        initView(view);
    }

    private void initView(View view) {
        mArrayListMaterial = new ArrayList<>();
        mArrayListCurriculum = new ArrayList<>();
        populateMaterials();
        populateKeyFeatures();

        mRecyclerViewCurriculum = (RecyclerView) view.findViewById(R.id.recyclerViewCurriculum);
        mCurriculumAdapter = new CurriculumAdapter(getActivity(), mArrayListCurriculum);
        mLinearLayoutManager = new LinearLayoutManager(getActivity());
        mRecyclerViewCurriculum.setLayoutManager(mLinearLayoutManager);
        mRecyclerViewCurriculum.setAdapter(mCurriculumAdapter);
        mRecyclerViewCurriculum.setItemAnimator(new DefaultItemAnimator());
    }

    private void populateMaterials() {
        mArrayListMaterial.add(new Material("12:00","pdf","","Sample Text","0"));
        mArrayListMaterial.add(new Material("12:00","pdf","","Sample Text","0"));
    }

    private void populateKeyFeatures() {
        mArrayListCurriculum.add(new Curriculum("UNIT 1",mArrayListMaterial));
        mArrayListCurriculum.add(new Curriculum("UNIT 2",mArrayListMaterial));
        mArrayListCurriculum.add(new Curriculum("UNIT 3",mArrayListMaterial));
    }
}

Answer 1

持有者中的bind方法是将数据传递给它的好方法。

在您的情况下，此bind方法应将Curriculum和Material对象作为参数。

在适配器的onBindViewHolder方法中，您应该调用此bind方法，而不是访问持有者的变量。

在you KeyFeatureViewHolder类中的方法实现中，您应该使用这些传递的参数并将它们显示在相应的UI元素中。

最后，要将Material对象数据转换为适配器，请将ArrayList<Material>添加为构造函数参数，就像使用Curriculum一样。

Answer 2

使用标题RecyclerView作为标题title作为标题，materials作为标题的项目。请看this example。

Answer 3

您需要为自己设计自定义列表。例如，拿一个像这样的对象。

public class ListItem {
    public curriculumName = null;
    public materialName = null;
}

现在在解析JSON字符串后填充此列表。获取您的第一个Curriculum并填充此对象

private ArrayList<ListItem> mListItemArray = new ArrayList<ListItem> ();

for(curriculum : mArrayListCurriculum) {

    ListItem mListItemHead = new ListItem();    
    mListItemHead.curriculumName = curriculum.getName();

    // Set the header here
    mListItemArray.add(mListItemHead);

    for(material : curriculum.getMaterials()){
        ListItem mListItem = new ListItem();
        mListItem.materialName = material.getName();

        // Add materials here
        mListItemArray.add(mListItem);
    }
}

现在，您有一个包含标题和材料的列表。当materialName中的mListItemArray为空时，它会识别出这是一个标头，反之亦然。

现在的诀窍是修改RecyclerView的适配器，以便将正确的视图绑定到列表中的项目。

您可以从this answer找到有关如何实现此期望行为的指示。

基本上，我们的想法是修改您的getItemViewType，以便在onBindViewHolder中传递正确的观点。您的getItemViewType可能如下所示。

@Override
public int getItemViewType(int position) {
    if (mListItemArray.get(position).curriculumName != null) {
        // This is where we'll add header.
        return HEADER_VIEW;
    }

    return super.getItemViewType(position);
}

创建RecyclerView时嵌套的ArrayList

3 个答案: