RecyclerView Multiple View Type

Question

I've a list of following model:

name
categoryName

Now, I've to build a recyclerview that groups all the entities with the same categoryName:

categoryName1
    name1
    name2
    name3
categoryName2
    name4
categoryName3
    name5
    name6

So I have two different row type (different styles). The list is ordered. I don't necessary need the code, but, what's the algorithm to use for the adapter? Can I solve this with only one cycle?

I'd like to avoid adding view to a vertical LinearLayout from code.

Answer 1

Your data should look like this:

public class CategorizedName {

    private Category category;
    private Collection<Name> names = null;

    public Category getCategory() {
        return category;
    }

    public Collection<Name> getNames() {
        return names;
    }

    // override hashCode and equals ...
}

In your adapter you should do something like this:

private static final int CATEGORY = 1;
private static final int NAME = 2;    

private Collection<CategorizedName> data;

@Override
public int getItemViewType(int position) {
    if (items.get(position) instanceof Category) {
        return CATEGORY;
    } else if (items.get(position) instanceof Name) {
        return NAME;
    }
    throw new RuntimeException('error');
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {

    RecyclerView.ViewHolder viewHolder;
    LayoutInflater inflater = LayoutInflater.from(viewGroup.getContext());

    switch (viewType) {
        case CATEGORY:
            View categoryView = inflater.inflate(R.layout.viewholder_category, viewGroup, false);
            viewHolder = new CategoryViewHolder(categoryView);
            break;
        case NAME:
            View nameView = inflater.inflate(R.layout.viewholder_name, viewGroup, false);
            viewHolder = new NameViewHolder(nameView);
            break;
    }
    return viewHolder;
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
      switch (viewHolder.getItemViewType()) {
          case USER:
              CategoryViewHolder categoryViewHolder = (CategoryViewHolder) viewHolder;
              bindCategoryViewHolder(categoryViewHolder, position);
              break;
          case IMAGE:
              NameViewHolder nameViewHolder = (NameViewHolder) viewHolder;
              bindNameViewHolder(nameViewHolder, position);
              break;
      }
}

Don't forget to create view holders.

EDIT 1: added data structure for adapter

Answer 2

You must override method public int getItemViewType(int position) of RecyclerView, and handle it in public void onCreateViewHolder(ViewGroup parent, int viewType)

Example:

enum Type{Name,Category}

@Override
public int getItemViewType(int position) {
   if (position == POSITION_CATEGORY_1 || position == POSITION_CATEGORY_2) {
      return Type.Category;
   } else {
      return Type.Name;}
   }
}

End bind:

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if(viewType == Type.Category.ordinal()){
        return new CategoryItemView(...);
    }else {
        return new CommonItemView(...);
    }
}