LinearLayoutManager - repetition in a circle

Question

Is there any easy way to make LinearLayoutManager to be as a circle (repetition items in a circle)?

I investigated it and found only way to make own custom LayoutManager, so it would be cool to find a way with less code

Answer 1

First thing to do is change your adapter's getItemCount() method to return Integer.MAX_VALUE. This is not actually infinite, but it's over two billion so I doubt anyone's going to scroll that far.

Next, whenever you retrieve an item from your data source, don't just use position. Instead, use position % dataSource.size()... this will repeat your items as the user scrolls.

Here's an example:

public class MainActivity extends AppCompatActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RecyclerView recycler = (RecyclerView) findViewById(R.id.recycler);
        recycler.setAdapter(new MyAdapter());
    }

    private static class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {

        private final List<String> items;

        private MyAdapter() {
            items = new ArrayList<>();
            items.add("A");
            items.add("B");
            items.add("C");
            items.add("D");
        }

        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            LayoutInflater inflater = LayoutInflater.from(parent.getContext());
            View itemView = inflater.inflate(R.layout.itemview, parent, false);
            return new MyViewHolder(itemView);
        }

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            String item = items.get(position % items.size());
            ((TextView) holder.itemView).setText(item);
        }

        @Override
        public int getItemCount() {
            return Integer.MAX_VALUE;
        }
    }


    private static class MyViewHolder extends RecyclerView.ViewHolder {

        public MyViewHolder(View itemView) {
            super(itemView);
        }
    }
}