ExpandRecyclerView

compile 'com.thoughtbot:expandablerecyclerview:1.0'

//Group
@SuppressLint("ParcelCreator")
public class GroupText extends ExpandableGroup<ChildText> {
    public GroupText(String title, List<ChildText> items) {
        super(title, items);
    }
}

//Child
public class ChildText implements Parcelable {
    private String name;

    public ChildText(Parcel in) {
        name = in.readString();
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public ChildText(String name) {
        this.name = name;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(name);
    }

    @Override
    public int describeContents() {
        return 0;
    }

    public static final Creator<ChildText> CREATOR = new Creator<ChildText>() {
        @Override
        public ChildText createFromParcel(Parcel in) {
            return new ChildText(in);
        }

        @Override
        public ChildText[] newArray(int size) {
            return new ChildText[size];
        }
    };
}

//Group
public class GroupContentViewHolder extends cn.expandrecyclerview.demo.viewholders.GroupViewHolder {

    private TextView name;

    public GroupContentViewHolder(View itemView) {
        super(itemView);
        name = (TextView) itemView.findViewById(R.id.mobile_os);
    }

    @Override
    public void expand() {
        name.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.mipmap.below_arrow_icon, 0);
    }

    @Override
    public void collapse() {
        name.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.mipmap.up_arrow, 0);
    }

    public void setGroupName(ExpandableGroup group) {
        osName.setText(group.getTitle());
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@android:color/black">

    <TextView
        android:id="@+id/mobile_os"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:drawablePadding="5dp"
        android:drawableRight="@mipmap/down_arrow"
        android:gravity="left|center"
        android:padding="8dp"
        android:textColor="#e6e600" />

</RelativeLayout>

//ChildViewHolder
public class ChildContentViewHolder extends cn.expandrecyclerview.demo.viewholders.ChildViewHolder {
    private TextView name;
    public ChildContentViewHolder(View itemView) {
        super(itemView);
        name = (TextView) itemView.findViewById(R.id.phone_name);
    }

    public void onBind(ChildText child, ExpandableGroup group) {
        name.setText(child.getName());
        if (group.getTitle().equals("水果")) {
            name.setCompoundDrawablesWithIntrinsicBounds(R.drawable.ic_launcher, 0, 0, 0);
        } else if (group.getTitle().equals("球类")) {
            name.setCompoundDrawablesWithIntrinsicBounds(R.drawable.ic_launcher, 0, 0, 0);
        } else {
            name.setCompoundDrawablesWithIntrinsicBounds(R.drawable.ic_launcher, 0, 0, 0);
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

    <TextView
        android:id="@+id/phone_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:padding="10dp"/>
</RelativeLayout>

public class RecyclerAdapter extends ExpandableRecyclerViewAdapter<OSViewHolder, PhoneViewHolder> {

    private Activity activity;

    public RecyclerAdapter(Activity activity, List<? extends ExpandableGroup> groups) {
        super(groups);
        this.activity = activity;
    }

    @Override
    public OSViewHolder onCreateGroupViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        View view = inflater.inflate(R.layout.group_view_holder, parent, false);
        return new GroupContentViewHolder(view);
    }

    @Override
    public PhoneViewHolder onCreateChildViewHolder(ViewGroup parent, final int viewType) {
        LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        View view = inflater.inflate(R.layout.child_view_holder, parent, false);
        return new ChildContentViewHolder(view);
    }

    @Override
    public void onBindChildViewHolder(ChildContentViewHolder holder, int flatPosition, ExpandableGroup group, int childIndex) {
        final ChildText child = ((GroupText) group).getItems().get(childIndex);
        holder.onBind(child,group);
    }

    @Override
    public void onBindGroupViewHolder(GroupContentViewHolder holder, int flatPosition, ExpandableGroup group) {
        holder.setGroupName(group);
    }
}

public class ExpandRecyclerViewActivity extends AppCompatActivity{


    private RecyclerView recyclerView;
    private ArrayList<GroupText> mobileOSes;
    private RecyclerAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_expand_recyclerview_layout);
        recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        mobileOSes = new ArrayList<>();

        setData();
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);

        adapter = new RecyclerAdapter(this, mobileOSes);
        recyclerView.setAdapter(adapter);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        adapter.onSaveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        adapter.onRestoreInstanceState(savedInstanceState);
    }

    private void setData() {
        ArrayList<ChildText> iphones = new ArrayList<>();
        iphones.add(new ChildText("苹果"));
        iphones.add(new ChildText("橘子"));
        iphones.add(new ChildText("芒果"));
        iphones.add(new ChildText("香蕉"));
        iphones.add(new ChildText("火龙果"));
        iphones.add(new ChildText("草莓"));
        iphones.add(new ChildText("柚子"));
        iphones.add(new ChildText("哈密瓜"));

        ArrayList<ChildText> nexus = new ArrayList<>();
        nexus.add(new ChildText("足球"));
        nexus.add(new ChildText("篮球"));
        nexus.add(new ChildText("乒乓球"));
        nexus.add(new ChildText("棒球"));
        nexus.add(new ChildText("保龄球"));
        nexus.add(new ChildText("溜溜球"));
        nexus.add(new ChildText("橄榄球"));

        ArrayList<ChildText> windowPhones = new ArrayList<>();
        windowPhones.add(new ChildText("单击游戏"));
        windowPhones.add(new ChildText("主机游戏"));
        windowPhones.add(new ChildText("FPS游戏"));
        windowPhones.add(new ChildText("挂机游戏"));
        windowPhones.add(new ChildText("小游戏"));
        windowPhones.add(new ChildText("手游"));

        mobileOSes.add(new GroupText("水果", iphones));
        mobileOSes.add(new GroupText("球类", nexus));
        mobileOSes.add(new GroupText("游戏", windowPhones));
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
    >

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