Creating an expandable RecyclerView

Question

I\'m trying to implement a recyclerview that behaves like my sketch below:

The idea is that there is a parent list, when an list item in the parent list is tapp

Answer 1

1.ExpandableRecyclerAdapter.class

public abstract class ExpandableRecyclerAdapter extends RecyclerView.Adapter {
    protected Context mContext;
    protected List allItems = new ArrayList<>();
    protected List visibleItems = new ArrayList<>();
    private List indexList = new ArrayList<>();
    private SparseIntArray expandMap = new SparseIntArray();
    private int mode;

    protected static final int TYPE_HEADER = 1000;

    private static final int ARROW_ROTATION_DURATION = 150;

    public static final int MODE_NORMAL = 0;
    public static final int MODE_ACCORDION = 1;

    public ExpandableRecyclerAdapter(Context context) {
    mContext = context;
    }

    public static class ListItem {
    public int ItemType;

    public ListItem(int itemType) {
        ItemType = itemType;
    }
    }

    @Override
    public long getItemId(int i) {
    return i;
    }

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

    protected View inflate(int resourceID, ViewGroup viewGroup) {
    return LayoutInflater.from(mContext).inflate(resourceID, viewGroup, false);
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
    public ViewHolder(View view) {
        super(view);
    }
    }

    public class HeaderViewHolder extends ViewHolder {
    ImageView arrow;

    public HeaderViewHolder(View view) {
        super(view);

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                toggleExpandedItems(getLayoutPosition(),false);
                /*if(isExpanded(getLayoutPosition())){
                    collapseItems(getLayoutPosition(),false);
                }else {
                    expandItems(getLayoutPosition(),true);
                }*/
            }
        });
    }

    public HeaderViewHolder(View view, final ImageView arrow) {
        super(view);

        this.arrow = arrow;

        arrow.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleClick();
            }
        });
    }

    protected void handleClick() {
        if (toggleExpandedItems(getLayoutPosition(), false)) {
            openArrow(arrow);
        } else {
            closeArrow(arrow);
        }
    }

    public void bind(int position) {
        arrow.setRotation(isExpanded(position) ? 90 : 0);
    }
    }

    public boolean toggleExpandedItems(int position, boolean notify) {
    if (isExpanded(position)) {
        collapseItems(position, notify);
        return false;
    } else {
        expandItems(position, notify);

        if (mode == MODE_ACCORDION) {
            collapseAllExcept(position);
        }

        return true;
    }
    }

    public void expandItems(int position, boolean notify) {
    int count = 0;
    int index = indexList.get(position);
    int insert = position;

    for (int i=index+1; i= 0;
}

@Override
public int getItemViewType(int position) {
    return visibleItems.get(position).ItemType;
}

public void setItems(List items) {
    allItems = items;
    List visibleItems = new ArrayList<>();
    expandMap.clear();
    indexList.clear();

    for (int i=0; i newIndexList = new ArrayList<>();

    for (int i=0; i 0) {
                newIndexList.add(allItemsPosition);
            }
        }

        int val = indexList.get(i);
        newIndexList.add(val < allItemsPosition ? val : val + direction);
        }

    indexList = newIndexList;
    }

    public void collapseAll() {
    collapseAllExcept(-1);
    }

    public void collapseAllExcept(int position) {
    for (int i=visibleItems.size()-1; i>=0; i--) {
        if (i != position && getItemViewType(i) == TYPE_HEADER) {
            if (isExpanded(i)) {
                collapseItems(i, true);
            }
        }
    }
    }

    public void expandAll() {
    for (int i=visibleItems.size()-1; i>=0; i--) {
        if (getItemViewType(i) == TYPE_HEADER) {
            if (!isExpanded(i)) {
                expandItems(i, true);
            }
        }
    }
    }

    public static void openArrow(View view) {
    view.animate().setDuration(ARROW_ROTATION_DURATION).rotation(180);

    }

    public static void closeArrow(View view) {
    view.animate().setDuration(ARROW_ROTATION_DURATION).rotation(0);
    }

    public int getMode() {
    return mode;
    }

    public void setMode(int mode) {
    this.mode = mode;
    }
}

2.activity_main

3.item_header

4.item_content.xml

5.Adapter

public class PeopleAdapter extends ExpandableRecyclerAdapter {
public static final int TYPE_PERSON = 1001;

public PeopleAdapter(Context context) {
    super(context);

    setItems(getSampleItems());
}

public static class PeopleListItem extends ExpandableRecyclerAdapter.ListItem {
    public String Text;

    public PeopleListItem(String group) {
        super(TYPE_HEADER);

        Text = group;
    }

    public PeopleListItem(String first, String last) {
        super(TYPE_PERSON);

        Text = first + " " + last;
    }
    }

    public class HeaderViewHolder extends ExpandableRecyclerAdapter.HeaderViewHolder {
    TextView name;

    public HeaderViewHolder(View view) {
        super(view, (ImageView) view.findViewById(R.id.img_arrow));

        name = (TextView) view.findViewById(R.id.txt_header_name);
    }

    public void bind(int position) {
        super.bind(position);

        name.setText(visibleItems.get(position).Text);
    }
    }

    public class PersonViewHolder extends ExpandableRecyclerAdapter.ViewHolder {
    EditText name;

    public PersonViewHolder(View view) {
        super(view);

        name = (EditText) view.findViewById(R.id.edt_description);
    }

    public void bind(int position) {
        name.setText(name.getText());
    }

    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    switch (viewType) {
        case TYPE_HEADER:
            return new HeaderViewHolder(inflate(R.layout.item_header, parent));
        case TYPE_PERSON:
        default:
            return new PersonViewHolder(inflate(R.layout.item_content, parent));
    }
    }

    @Override
    public void onBindViewHolder(ExpandableRecyclerAdapter.ViewHolder holder, int position) {
    switch (getItemViewType(position)) {
        case TYPE_HEADER:
            ((HeaderViewHolder) holder).bind(position);
            break;
        case TYPE_PERSON:
        default:
            ((PersonViewHolder) holder).bind(position);
            break;
    }
    }

    private List getSampleItems() {
    List items = new ArrayList<>();
    items.add(new PeopleListItem("Friends"));
    items.add(new PeopleListItem("", ""));
    items.add(new PeopleListItem("Friends"));
    items.add(new PeopleListItem("", ""));
    return items;
}

}

6.MainActivity.java

public class MainActivity extends AppCompatActivity {
RecyclerView recycler;
PeopleAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    recycler = (RecyclerView) findViewById(R.id.main_recycler);

    adapter = new PeopleAdapter(this);
    adapter.setMode(ExpandableRecyclerAdapter.MODE_ACCORDION);
    recycler.setLayoutManager(new LinearLayoutManager(this));
    recycler.setAdapter(adapter);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    super.onCreateOptionsMenu(menu);

    getMenuInflater().inflate(R.menu.menu_main, menu);

    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.action_expand_all:
            adapter.expandAll();
            return true;
        case R.id.action_collapse_all:
            adapter.collapseAll();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}
}