¿Cómo puedo implementar una Lista de Expandir / Contraer el Material de Diseño en Android?

Sí, puedes implementarlo fácilmente con la biblioteca SectionedRecyclerViewAdapter . Aquí hay un ejemplo completo de trabajo.

Básicamente, se crea una clase de sección:

class MySection extends StatelessSection { String title; List<String> list; boolean expanded = true; // true if you want it to be displayed expanded initially public MySection(String title, List<String> list) { // call constructor with layout resources for this Section header, footer and items super(R.layout.section_header, R.layout.section_item); this.title = title; this.list = list; } @Override public int getContentItemsTotal() { return expanded? list.size() : 0; } @Override public RecyclerView.ViewHolder getItemViewHolder(View view) { // return a custom instance of ViewHolder for the items of this section return new MyItemViewHolder(view); } @Override public void onBindItemViewHolder(RecyclerView.ViewHolder holder, int position) { MyItemViewHolder itemHolder = (MyItemViewHolder) holder; // bind your view here itemHolder.tvItem.setText(list.get(position)); } @Override public RecyclerView.ViewHolder getHeaderViewHolder(View view) { return new SimpleHeaderViewHolder(view); } @Override public void onBindHeaderViewHolder(RecyclerView.ViewHolder holder) { MyHeaderViewHolder headerHolder = (MyHeaderViewHolder) holder; // bind your header view here headerHolder.tvItem.setText(title); // handles the click on the header to toggle the expanded variable headerHolder.rootView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { expanded = !expanded; headerHolder.imgArrow.setImageResource( expanded ? R.drawable.ic_keyboard_arrow_up_black_18dp : R.drawable.ic_keyboard_arrow_down_black_18dp ); sectionAdapter.notifyDataSetChanged(); } }); } } 

A continuación, configure el RecyclerView con sus secciones:

 // Create an instance of SectionedRecyclerViewAdapter SectionedRecyclerViewAdapter sectionAdapter = new SectionedRecyclerViewAdapter(); // Create your sections with the list of data for each topic MySection topic1Section = new MySection("Attractions", attractionsList); MySection topic2Section = new MySection("Dining", diningList); // Add your Sections to the adapter sectionAdapter.addSection(topic1Section); sectionAdapter.addSection(topic2Section); // Set up your RecyclerView with the SectionedRecyclerViewAdapter RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerview); recyclerView.setLayoutManager(new LinearLayoutManager(getContext())); recyclerView.setAdapter(sectionAdapter); 

Implementé una lista con esta biblioteca:
Ampliación-reciclado-vista

Hay un blog relacionado, pero se refiere a una versión antigua:
Expanda un RecyclerView en cuatro pasos

Es básicamente un adaptador donde se puede suministrar una lista de elementos padre que contienen a los niños. También tiene que especificar dos titulares para los padres y los niños. Vea la página de la biblioteca para más detalles.

 class MyChild { // add data } class MyParentListItem implements ParentListItem { private final List<MyChild> mChildren; MyParentListItem(List<MyChild> children) { mChildren = children; // add other data } @Override public List<MyChild> getChildItemList() { return mChildren; } @Override public boolean isInitiallyExpanded() { return false; } } class MyParentViewHolder extends ParentViewHolder { MyParentViewHolder(View itemView) { super(itemView); // get other views with itemView.findViewById(..); } } class MyChildViewHolder extends ChildViewHolder { MyParentViewHolder(View itemView) { super(itemView); // get other views with itemView.findViewById(..); } } public class MyExpandableAdapter extends ExpandableRecyclerAdapter<MyParentViewHolder, MyChildViewHolder> { private final LayoutInflater mInflater; public MyExpandableAdapter(List<MyParentListItem> parentItemList, Context context) { super(parentItemList); mInflater = LayoutInflater.from(context); } @Override public MyParentViewHolder onCreateParentViewHolder(ViewGroup parentViewGroup) { final View itemView = mInflater.inflate(R.layout.parent_layout, parentViewGroup, false); return new MyParentViewHolder(itemView); } @Override public MyChildViewHolder onCreateChildViewHolder(ViewGroup childViewGroup) { final View itemView = mInflater.inflate(R.layout.child_layout, childViewGroup, false); return new MyChildViewHolder(itemView); } // bind data to holders in the onBind methods }